Range Extension options Torqeedo 1003 and Ultralight

Travel 1003—the most popular Torqeedo

[updated to include latest battery info] I’m often asked about range extension for a 1003, and occasionally for an Ultralight. Of course it would be great if we could connect these motors to the large Torqeedo battery—the 26-104. Alas, the voltage is different and it does not have a GPS built in so we need to look further afield and be a bit creative about how we engineer a solution to this.

There are a couple of options available already and lets explore these first before we resort to more lateral thinking.  For many owners we find that ‘range anxiety’ is something that they encounter in the decision making process before buying a Torqeedo, but then they find that in practise the range is quite adequate. We find this phenomenon in electric vehicles as well and just as an aside lets take a quick look at what’s happening in that realm.

Solar roof Prius

A new pattern in electric vehicles is the plug-in hybrid such as the Volt, which has an internal combustion engine to assuage range anxiety.  But owners are finding is that despite a paltry electric only range of 50 km that they hardly ever go the petrol station to fill up.  Here in Australia there was a conversion shop that converts Prius cars to have a plug-in electric option.  And they found that one of the problems is the petrol can go stale in the tank because they hardly ever need to use the petrol engine.  And so at the time they’ve added a feature—the purge button—to force the internal combustion engine to run and burn some fuel before it goes stale.  Anyway, the bottom line of this is that we tend to be overly concerned about range of electric vehicles in general.  And even though the range limitation is real, its rare for most users that they exceed the range available.

And so back to boating, this pattern seems to be the case with Torqeedo 1003 owners as well.  Those who have in mind to add a spare battery mostly find that its not really a problem and can get by fine with one battery.

Coming into Sydney heads—the city skyline visible to the right of the mother ship

To do a practical test of range I took a trip by zodiac from Pittwater to Sydney Harbour by sea—a distance of around 20 nautical miles and did it with a single battery assisted by Solbian solar panels.  I was using the old 400 watt-hour battery and overall I used around 700 watt-hours for the trip.  For that trip the tide was against us leaving Broken Bay and against us coming into Sydney Harbour and so I think that it could be done with a single 500 watt-hour battery, and no solar assistance if the tides are used to better advantage.

But anyway, back to the chase…  even though we see that range anxiety is a unfounded concern for most users we still do have a problem for some who do need to regularly exceed the range available in the 1003 battery and the Ultralight battery.  And for these users there we have some ways to extend the range and to do so we can make use of aspects of the design in a different way to what was intended. But before going there lets fully explore the alternatives that are designed into the products.

The simplest solution is to just add a second battery and that will solve the problem in many cases.

1003 Range and time with two batteries Speed in knots Range in nm Run time hrs
Slow speed – 50 watts 1.5 to 2 25 to 40 20
Medium speed – 150 watts 2.5 to 3 17 to 21 7
Full speed 4 to 5 4 to 5 1

But that still leaves a few categories un-answered…

Jeff Keys with Ultralight on Solstice GTS

Lets consider Ultralight users who venture off the beaten track for days or weeks at a time and will be nowhere near a plug-in point to be able to recharge from the grid. Here’s where the second battery and a solar panel can be an ideal solution. To unroll a solar panel on a kayak when travelling is rarely feasible but by having a spare battery that can be left at the campsite while you go exploring can allow you to return to a fully charged battery on sunny days. You can use a Torqeedo solar panel or one of our folding solar panels any 24 volt solar panel with the right connections.  You can even use two 12v panels in series, or as we did on the zodiac trip, four six volt panels in series. Just be sure that the maximum output does not exceed 4 amps if you are using an old battery (pre 2015).  With the old model battery, any more than this will exceed the circuitry of the battery’s built-in charge controller and you’ll blow an internal fuse which requires return to service centre to repair.  The newer batteries are internally limited to 4 amps so you don’t have to worry about this, and can connect as much solar as you want, the battery will just take the 4 amps it needs.

The nice thing about this solar charge channel is that its working at around 30 volts and if we have enough solar panels, the power that we can get into the battery at 4 amps is 120 watts.  This turns out to be around three times greater than the plug-in charger that comes with this battery. And here is the clue to how we can extend the range for other users, such as those with small sailing boats which already have a 12v battery on board for house power.

So this brings us nicely to talk about the main group who would like to get a Torqeedo 1003 but it does not have enough range.  And in this case, it really does not have enough range.  The scenario is this.  You have a small sailing boat, around 20ft in length, and you often need to travel under power in navigation channels or rivers and where you might need to go against a current for a while, or for a long distance.

By charging the battery at 120 watts as you go, the range improves markedly for low power operation and also for intermittent high power operation.

For low power operation, say at around 200 watts, which in my solar boat equates to a nice cruising speed of 3 knots, 120 watts of this power would be coming from the house battery and only 80 watts from the Torqeedo battery.  Normally running at 200 watts would indicate a range of 4.5 hours (that is, 915 watthr battery capacity divided by 200) but when only drawing 80 watts from the battery it will provide a range over 11 hours.  If during that time the boat is anchored, say for fishing, or under sail, the Torqeedo battery is being charged.

For intermittent high power operation, the range can also be extended.  Consider the case of a Torqeedo 1003 used on a racing yacht.  Say it requires running at full speed for 30 minutes to get to the start line on time, this would use up about 500 wathrs, or over 50% of the battery capacity.  Then while racing for three hours the battery is being charged at 120 watts, this would recover 360 watthrs, or most the energy used.  Or if we look at it another way, say the battery is on charge from the moment the boat leaves the dock till when it returns, 4 hour later, it will have received 480 watthrs of power.

With any of these ideas that rely on taking power from a separate house battery its important to make sure the house battery is of sufficient capacity to provide the energy needed.  Such a battery may be topped up from solar panels.

Since first writing this range extension article Torqeedo has introduced a new range of batteries which have a different charging circuit inside and can take charge from a range of sources.  As long as the voltage is between 10 and 50 volts you can charge from whatever source is available. The battery will take up to 4 amps at whatever voltage is available.  For voltages above 30 the amps drawn will be downgraded so that the maximum charge rate is 120 watts. The new batteries are far more adaptable than the old model and you can charge them from a variety of sources.

The battery model numbers and their characteristics are listed below:

Battery Model Charge rate Voltage range
503 pre 2015 1144-00 <4 amps 12-18, 30-60
1003 pre 2015 1145-00 <4amps 12-18, 30-60
403 pre 2015 1413-00 <4amps 12-18, 30-60
1003 from 2015 1147-00 4 amps 10-50
1003 from 2015 1148-00 4 amps 10-50

To summarise I’ve laid out a table showing the various ways of charging while underway:

Method Power Price Notes
Direct from 12v source (old battery) 23 watts $88 This is a cable to connect from house battery to Torqeedo Battery
Direct from 12v source (new battery) 50 watts $88 This is a cable to connect from house battery to Torqeedo battery
Direct from 24v source (new battery) 100 watts $88 This is cable to connect from 24v house battery to Torqeedo battery
240v charger 45 watts $90 To charge from a house battery this also requires an inverter to produce 240v. This charger comes with every 1003

DC-DC converter

with 36v output

120 watts $100-$400 This device is wired to house battery and a cable run to the 1003 battery charge socket

If you have further questions on this topic you can submit a public reply on this topic below, or submit a private enquiry using the form.


  1. If you are motoring at night a solar assist is not available and you have to rely on your battery capacity. Thanks. Steve S.

  2. Chris,
    I own a torqeedo 1003, but I want to extend the range. A good speed for my boat (wooden sailing traditional venetian boat) is 200W.
    I think I have 2 options:
    1. extra 520 battery: I run 5,20 hours, cost around 600 Euros
    2. extra stationary battery: 55 Ah. Questions:
    2.1. I need a cord to charge from the battery: I need to have it prepared by somebody: Do I need some specific protections on it?
    2.2. You write that I get 120W from the external battery and 80 from the torqeedo battery; I assume this is self.determined (but from expensive controllers)
    2.3. Do I need a stationary battery like optima yellow? or any other brand will do? can I discharge it completely without destroying my battery?
    2.4. Can I recharge this battery with solar panel? If I use a 40W 12V solar panel, will this increase substantially the duration of the external battery capacity? can I plug in this panel directly on the motor via a cord similar to what is needed for the external battery?
    I cant have 2 panels because of space problems
    2.1 + 2.2.+2.3 + charger make around 250 Euros: a bit less than half the cost of a new 520 battery, but with the same result. Is this correct?
    Thank for any help. regards

  3. Buon Giorno Guiseppe

    I would love to see photo of your boat… it would be nice to put it here so that we can see what you’re talking about.

    And now to the points you raise and the questions:

    1. You will have figured the run time based on two batteries of 520 watthrs, giving a total of 1040 watthrs. And when divided by the power requirements of 200watts, means you can for a total of 5.20 hrs

    2 Lets assume a 55 ah Optima. The capacity of this when measured as watthrs is 55 x 12 = 660 watthrs to totally empty. Or if you used 520 watthrs it would leave a nice buffer so that you have not fully discharged the battery.

    2.1 You can use a simple cable that you can prepare yourself – there is no protection or special requirements. All you need is clips at one end to attach to stationary battery, and a suitable plug to match the Torqeedo battery at the other end. The difficulty with this is that the charge rate is only about 25 watts.

    2.2 To get 120 watt from the external battery into the Torqeedo battery you need a suitable voltage converter to get he voltage to around 30 volts. The voltage converter needs to be limited to 120 watt capacity so that the maximum current does not exceed the 4 amps specified by Torqeedo as maximum.

    2.3 Any good quality brand will do. But in my experience the optimas have performed well under adverse treatment such as total discharge. Other brands we have tested have been destroyed a single complete discharge. Even if you do get an optima it will last longer if you leave some power remaining in the battery. Say 10 to 20%, and then re-charge it as soon as you are able.

    2.4 If you use a 40 watt solar panel you can expect to harvest about 3 to 5 times its rating from the sun each day. What I mean is that for a 40 watt panel you could expect 120 to 200 watthrs of power to be gained from the sun. The 3 hours seems to be in practise what I can expect on a boat. It is difficult to maintain an optimum angle to the sun when on a running boat. Under ideal conditions you might get as high as 5 times the rating. As you can see 120 watthrs does not give a substantial improvement. A 12v panel cannot be plugged directly into the Torqeedo battery.

    In my opinion the advantage of a solar panel can be realised if you are away from the grid for many days at a time, or have substantial area available to place solar panels. Or if it is inconvenient to bring your Torqeedo battery to the grid. Do any of these apply to you?

    An advantage of the 12v battery could be that you can run other devices on the boat, but you have mentioned any of this so I assume it is not important.

    If I understand your situation properly I think you would be best served by getting an extra 520 watthr battery. As well it is the simplest option.



  4. Is it possible for the ultralight model to use the larger 520AH battery intended for the Travel 1003?

    • Hi Kerbie, yes the 520 WH battery can be used on the ultralight. The connections are identical and use the same charger as well. I have a customer who has chosen this option and now uses this as his main battery and allocates the ultralight battery as the reserve.

      cheers, chris

  5. Hello,

    in Torqeedo catalog says that voltage should be between 24-60V and charging current up to 4A…So it would be possible to use step-up converter 12-48 (48*4 = 192W) with 180W limitation for example…or when it comes to solar panels (like Solbian for example, CP140 with 18V and 7.8A) a charge booster to 48V and all the W values could be utilized…


    I know it’s not cheap, but since they have a good efficiency till half the power (speed does not increase much but the running time and distance does decrease a lot) would it be a good solution to use two 1003 models? Mounting and steering is a challenge, specially the steering, but then both could run on half throttle and push for longer and faster…
    Did anyone try that?

    thanks for advice in advance 🙂

    • I was thinking along those lines too, to begin with. But there is a problem with this line of thinking…

      Its true that the output of a step-up converter would be equivalent to a 180w but that is not what is getting into the battery.

      We need to consider the voltage of the battery and it is around 31 or 32 volts. (I am in a train just now and my notes about this are not close by). Even though the voltage coming to the battery is say 48v, it is only charging at whatever the battery voltage is at the time. but lets say around 30 volts. And so the maximum we can expect to charge at is around 120 watts.

      And keeping this in mind, you might as well only convert to a voltage of say 32 so that there is no power wasted.

      Your other question about using two 1003 motors together is also a good question and probably what a many have speculated about.

      We have tried this kind of thing in practise using twin cruise 4 on a catamaran. What we find is that there is very little difference, and so small that it is difficult to measure with confidence.

      It seems that the speed/power curve belongs to the boat, rather than the motors. And the shape of this curve does not change depending on how many motors are running.

      If the boat requires 2000 watts to do 4 knots with one motor, it also requires approximately 2000 watts from two motors. That would be 1000 watts from each motor. And similar for other speeds. I have not done the test with 1003 but I expect the principle remains the same.

      We did notice that a single motor, rather than two, was generally very slightly more efficient but the difference was very small and could easily be due to observation errors. So we could not be sure that there was any real difference.

      The decreasing efficiency and range reduction that we see in the charts is a result of the hull friction and wave making drag rather than anything to do with motor efficiency.

      It would be good to run these tests on more cases to verify our findings.



  6. Hello Chris,

    Thanks for the fast reply.

    Regarding the charging process, I understand it, I wasn’t thinking about it as charging the battery, more like giving energy to the motor … Don’t know how the regulation is handling this, was hoping a bit like solar controllers where the power needed is combined from the battery and the solar, so the current of the solar is extended with battery current. But if its 120W that is also more then the 40-45 of that flexible solar panel. The price of it is high due to being so flexible, for transport and Bimini mounting the 20-25% flexibility of the Solbians would be enough I think. That would also mean that a 140W panel is the upper limit that can be used for single motor, considering that it will very unlikely produce 140W ever.

    Regarding the twin 1003… Ones we reach the limits of the boat, I would say true, no point in using multiple motors. And probably it’s not even good from speed/distance optimization perspective to go close to those limits. The curve is linear probably only at lower end 🙂 . But in case not even the power of two motors are reaching the limits, using two on 150-200W could give a speed as one was used on 300-400W but the range would increase enormous .
    I’m going today to meet with the local dealer here, the German Team send me right away with my questions to them, even tho my questions are very specific and probably very difficult to answer from a sales point of view.
    Hope they are not only salesmens.
    Will post here further findings, maybe I manage to convince them to try out these things. I don’t mind paying for a solution that works, but would hurt me if I have to experiment blindly.


    • Hi Laszlo,
      I think you’re right that the solar panel would be unlikely to produce 140W ever. So why not hook two 80 watt panels together in series then you don’t need a voltage step-up device? Check the spec from Solbian and I think you’ll find the maximum current is around 4 amps. And add to this the unlikely possibility that it will ever produce its rated output, and it should be good. Just to be sure you put a 4amp fuse in line so that it would fail first rather than an internal fuse in the battery, which requires return to service partner to replace.

      I think I get your drift that the important thing for you is no external batteries and being able to increase the range by using two batteries. Even so I think you’ll only increase the range by doubling, not any more from efficiency. Of course the use of the solar panel(s) will increase the range also.



  7. Why not just buy a Torqeedo 801 with the battery adapter? Then you can connect the motor to any battery combination you would prefer. Thanks. Steve S.

    • Hi Steve,

      There’s a few reasons why I wouldn’t recommend the 801… To begin with it is an outdated model which means it is not so well supported. But for me some important aspects are that the motor is much better in a number of ways. The efficiency is improved by 10% over the 801 and this is significant when looking for maximum range. The range calculator is useful in this scenario that Laszlo speaks of where you wish to maximise range. When running you can try different settings to get the best outcome and this ability is not available on the 801.



  8. Hello,

    The dealer here is great, once I decide what direction to go, he will be The Man…
    I wanted to avoid batteries completely. That is why I’m sticking to the 1003 and not going into cruise direction. Battery came into the picture as temporary solution, since frankly, if I go for an inflatable ( currently I’m thinking about an Allroundmarin Poker 430 HD) with twin 1003, that is a nice amount. Not sure will I be able to also charge both Torqeedo’s with solar panels. The minimum setup is boat+1003+Bimini+step-up battery, the full would be the twin setup with steering wheel and solar charge…
    Would like to minimize the risks, so I’m checking the possibilities, not that something comes up that will destroy the joy of this.

    I’m surprised that solbian did not come up with a Torqeedo package…or I’m just looking in wrong places…

  9. Hello Chris,

    Yes, two Solbian 80’s should eliminate the booster…

  10. The battery adapter on the 801 lets you think outside the box. You could use a small Honda generator with a DC charger/power supply (Samlex 24v 15 amp) to charge your battery bank or power the motor with the 15 amp output of the Samlex thru the battery bank. The more options you have the easier it is to find a solution. Thanks. Steve S.

  11. Hello again,

    Compared the torqeedo single and twin setup values, they are not for the same boats, but I think I’m getting the message Chris. At least if you tried to explain me that with twin 1003 I’ll get there faster, but will not get much further.
    Also found ascent solar 45W rollable panels, 2-2.2m long, but narrow, will fit 4 on a longer Bimini and then the current limitation is not an issue. They are under 4A. Solbian can go over, from power they are better, these are cheaper.

    Still searching… 🙂

  12. Hi Chris

    Do you know if the Hobie Evolve can be connected to a Travel 1003 520 wH battery as well?

    I have a hobie kayak and I too would like to extend the range. If this option is available, then that is the path I’d like to take.


    • Yes it can be done and a few eVolve users have taken that option. Its likely that the 520 wh would then become the main battery and the eVolve can be the “spare”. Keep in mind that the physical size is bigger and has some horns for connecting to the 1003. It may not fit inside the kayak.



  13. I am curious if someone could explain why a 12v power pack can charge the battery but a 12V solar panel outputting up to 22V can’t. Why does the solar panel need to be 24V? Does it matter if you use a solar charge controller on the 12V panel?

    • Hi George, Its weird huh. Its genesis is related to the battery voltage being a 24 to 33 volts depending on state of charge, and to charge directly you need a voltage higher than this, which is the solar panel voltage of a 24v solar panel. And oddly enough, the charger that comes with the battery outputs 12v DC. Internally the battery has a converter to go from the 12v dc input to the voltage required by the battery. Why it is not suitable to take a higher voltage I do not know. But it does not and Torqeedo has provided two charge channels, one for 12v input and one for a voltage higher than battery voltage. To arbitrate between them there is a voltage sensitive device internally which directs power either to the converter, or direct to the battery. I suspect the cutoff is somewhere around 16 volts and anything over this goes direct. But if its voltage is still less than battery voltage nothing happens.

      Adding a charge controller to a 12v panel does not work. You can add a 12v to 30v dc-dc converter and that will work.

      I have now sourced some suitable 24v solar panels that are semiflexible and I will list them soon in the online store. They will be $300 for a 60 watt panel. More news on this soon.



      • In my opinion this is the most interesting discussion about the torqeedo motor. I have been an owner of Torqeedo Travel 1003 motor for two years and I use it on a small 13 foot beach catamaran. Chris and others answered many questions I have had until finding those pages.

        However I am still not sure if I clearly understand different charging rates of the torqeedo battery which possibly depend on the power source input voltage. This is how I think the system works:

        1. 100-240Vac/12Vdc originaly supplied charger (power addapter):
        Output voltage of the charger is 12V, output current 4A (written on the charger housing). Using the original charger you have 48W charge power. This power rating can be confirmed by measuring the charging time. The charging process is internally controlled.

        2. On-board 12V power supply:
        I can read from your posts that the charging power is somehow limited to 25W. I have no idea how the internal charging controller can distinguish between 12V from the AC/DC power addapter and 12V from the onboard batteries. I think charging power here must be more or less the same – 48W,

        3. Solar power 24V:

        I do not think that internal controller connects solar panel voltage directly to the battery. I would think charging LiMn battery is quite a sophisticated process independed of the power source. I can hardly believe that charging power, comming from the solar panels is higher than 48W. Of course there might be some power losses due to voltage conversion, but this makes minimal difference in my opinion. The main difference with the solar panel is that if your solar panel is able to generate more power that is needed for charging the batteries, you can use it for running the motor. On the other hand if your motor needs more power that your solar panel can generate, extra power comes from the battery.

        One more argument for limited charging power: If charging with 30V would be faster, why Torqeedo does not supply 100-240Vac/30Vdc mains charger in the package.

        Please, give me your opinion Chris.

        All the best from Adriatic

        • Hi Jernej, Sorry I did not reply to your message until now (I had been really busy with the solar boat being out of the water and needing some projects done and my attention to this was lacking). Your point 2 is something I wonder about as well. I don’t know why but it is what i have seen when I measure the charge rate. It is based only on one observation and I think it would be helpful if I did it again to double check. Your point 3 can be explained because the limiting factor is the maximum current that the internal circuitry can take is 4 amps. 4 amps at 12v is 48 watts. 4 amps at 30 volts is 120 watts. The only path for the power from the solar panels is through the battery circuitry, and then either to the battery, or to the motor if it is running.
          Torqeedo does now offer a fast charger as an option.


        • I have a small sailing cruised (pegasus prelude 19ft 1 tonne). I have measured the amperage from a 12volt lead coming from a 88ah lead acid battery as 2.5- 3 amps(30-36watts). The lead acid battery is charged by a 28watt panel that, on a good summer day in the UK gives 1.7amps (20.5 watts)

          At 2.5 mph, I consume about 130 watts, in still water, a range of about 10 miles
          at 4 mph, I consume about 350 watts a range of about 6 miles

          using my lead whilst running in the first case increases my range to about 13 miles
          However, in the 4 mph case, the range is only extended to 6.5 miles.

          The point I want to make is that if you are considering the 12v cable option, the increase in range is very speed dependant.

          In typical weekend sailing, I use about half a battery. and I recharge the battery over night. The solar panel fully recharges the lead acid battery over the 5 week days. Solar power is all that I have used this summer.

          One very effective use I have found is that, when motor sailing on a beat in a light wind, so as to keep the apparent wind direction good, the range is dramatically increased some times to as much as 60 miles. But quite often over 20 miles. I think that the great low speed torque of the 1003 contributes a lot then, so slow that you can see the prop turning.

          Hope this helps

          cheers Bob High

  14. Based upon the information here, I would think the best option is a DC DC converter to about 32v. Ideally, the output voltage should be adjustable. This provided the flexibility of using any device to extend the range. The main issue is that at 12V the system will only charge and not run. At some voltage around 16v, the system will not charge and switches over to allow the operator to run with the external power source, however, if that external power source voltage isn’t equal or above the battery, then nothing will happen. This creates a “deadband” between the 16V to at least 24V to 31V or so depending on the state of charge. This means the panel must output a high voltage or it will not be effective.

    Amazon has a number of DC DC converters that seem to fit the needs. I think it is probably the best option. Perhaps TheTorqeedoShop could carry a nice converter.

    I will say, this site has some of the best information anywhere on these motors. I’ve really appreciated the effort taken to provide accurate and useful information.


  15. George, Chris, and others…

    Do we know that increasing input voltage actual results in more output power? It’s not clear to me that power is limited by voltage as opposed to other factors.

    Has this option been tested on the water or is it theoretical at this point? Has Torqeedo confirmed this and provided updated specifications on the true maximum input voltage and what the power/voltage/current limits are?

    • Hi Eugene, I’m not entirely sure of the context of your question and it is relevant here, and the answer would be both yes and no. In the broader context changing voltage from 12v to say 32 volts does increase the power that goes into the battery. For now lets assume charge current is 4 amps. So the power into the battery would go from 48 watts to around 120 watts. The main factor at play here is that there are two charge channels, and in between these two points there is a gap where there is no effect. For example if you put in 20 volts you get nothing. (Its while since I did the tests and I have forgotten the actual values, but these numbers are about right).

      If you go higher than the voltage of the battery, you will be wasting power. Just like any battery and charging system, the power that is actually delivered into the battery is limited by the battery voltage. If your solar panel is putting out, say, 40 volts at 4 amps, you might expect that this power of 160 watts could available for use, but the power that is delivered will be limited by battery voltage which could be as low as 26 volts. The power available for propulsion in this example would be 26 x 4 = 104 watts.

      [Aside: It is this gap between solar panel output and battery voltage that is made use of by Maximum Power Point Tracking solar charge controllers. They work by dropping the voltage and increasing the amps going to the battery.]

      Please keep in mind that we have to be really careful never to go over 4 amps, and just to be sure, it is probably best to limit input current to say 3.5 amps so that we don’t inadvertently blow a fuse internally which can result in an expensive return to dealer repair. The techniques suggested here are not recommended by Torqeedo so please be ware that these experiments are at your own risk.

      On the solar zodiac trip from Pittwater to Sydney we had 160 watts of solar panels and on the day I occasionally saw outputs above 3 amps. The motor was running at about 80 watts and a few times during the trip the battery was being charged so we know the input power did sometimes exceed 80 watts.

  16. Hi, I’m a Pom but I hope you will allow me to join the discussion.
    I have a 1003S and it’s great !
    I have read through the discussion on charging and was wondering if a spare solar panel which I have would trickle charge the battery?
    It’s a Solara S60M36 http://www.barden-ukshop.com/solara-s60m36-solar-panel-145-p.asp
    If the link won’t open then the spec is as follows ….
    Peak Power 18W
    System Volts 12V
    Voltage at peak power 19V
    Open circuit voltage 22.6V
    Current at peak power 0.94A
    Short circuit current 1.1A
    Although I’m in the UK we do get sunshine from time to time !

    • Crikey, a Pom on our blog! You’re very very welcome to join in. I’ll take your word for it that you do get sunshine there 🙂

      I know the Solara panels and have used them on my solar boat, and my trimaran Current Sunshine. If you have two of them wired together in series it would work ok, but one won’t do it. The Torqeedo battery needs a 24v panel to charge from and the Solara panels are 12v. The maximum amps that you can charge with is 4 amps, and so your panel at 0.94 amps is ok. Well, two of them in series that is. Do you have only the one panel?

      The odd thing is that you can connect a 12v battery directly to the charge socket of the Torqeedo battery and it will charge from there. So you could use say a small 12v battery such as from a motor bike and charge this battery with your solar panel, and then charge your Torqeedo battery from there. It would drain it fairly quickly and so it would be important to monitor the voltage and stop the charge when the voltage gets down to say 12v.

      I hope that helps…



  17. G’day Chris 🙂 thanks for replying.
    Yes I have a cable to charge the 1003 battery directly from the boats batteries. I was hoping that my physically small solar panel would do the job. If 2 in series will work then I will consider buying another panel. The Torqeedo solar panel is expensive and enormous!
    By the way it’s sunny here in Cornwall today and the temp is 18deg, not bad for mid October!

    • Hi Steve,
      The charge rate direct from your boat’s batteries is around 25 watts. The charge rate you might expect from two Solara panels in series will be similar in good conditions and would max out at 36 watts in perfect conditions. In my experience its unusual to see full output from solar panels on a boat. They are rarely oriented nicely for the sun’s angle and direction. (easy enough to do on a fixed installation). And then in cloudy and overcast conditions the output would be well less than 25 watts. On balance I wonder if the setup you already have would give you the best results? And your solara panel can charge your your house batteries to try to keep up with the demand from charging the Torqeedo. Of course adding another panel will help with that. And the energy is available for other tasks as well.

      What boat are running this on?

      Cheers, Chris

  18. I hope this works, this is my boat

    And this is the tender the Torqeedo drives

    • Wow! Awesome boat. And cool dinghy. And now I get it, you could take two small Solara panels with you on the dinghy for some range extension. You’ll see in the zodiac trip that I had four 6v solar panels linked together in series to give the required 24volts for the battery.

  19. Had a quick look at the video, busy now but will look again in the morning. Basically my idea is to solar trickle charge the battery while the Torqeedo is not in use. Range extension as such not a problem. I realise I can charge from the ship but solar charging would be great.

  20. i found a dc to dc 12 volt (10-20v) step up to 36 volt 4 amp power adapter regulator on ebay. do you think this unit charge the travel battery for my 1003? from my 12 volt house battery bank? i read on another torqeedo dealer’s site (murry’s) the you can charge the travel battery from any solar panel with a voltage between 24 and 60 volts and a charging current 4 amps max. so why not any source with a voltage between 24 and 60 volts and a charging current 4 amps max?

    • Hi Jim,
      That should work fine. Just be sure that it doesn’t exceed 4 amps. It could be a good idea to put a 4 amp fuse in line externally so that if it does exceed 4 amps it may hopefully blow the external fuse before a fuse inside the battery. When you get it you could test it by running some other load and measure the current just to be sure what its operating point is. Quite often manufacturers round up or down the actual current to a nominal value, to make a “nicer” looking number.
      Cheers, Chris

  21. hi chris

    would 2 of this flexible panel in serial also work?
    i can get them for 99euro euch.

    Weight (kg) 0,93
    Peak power (Wp) 60
    MPP voltage (V) 17,5
    MPP current (A) 3,43
    Voltage without load (V) 21
    Short-circuit current (A) 3,84
    Efficiency of solar panel (%) 19,6
    Height (mm) 725
    Width (mm) 535
    Depth (mm) 3
    Nominal Voltage (V) 12
    Number of cells 32

    • Hi Rajiv,

      That would work fine. Again as suggested to Jim, why not put a 4amp fuse in line externally to give an easily accessible protection to guard against too high a current even if momentary due to ideal conditions of full sun and cloud reflection



  22. hi chris
    it’s me again, i think i found a good solution.
    i will use a dc-dc stepup converter, found on e-bay as follows:

    DC Converter Module 12V(10-20V) Step up to 36V 4A 144W

    and the flexible solarpanel found on:
    for 265.- euro.

    tech-spec as follows:
    Weight (kg) 2,31
    Peak power (Wp) 130
    MPP voltage (V) 16,64
    MPP current (A) 7,87
    Voltage without load (V) 19,84
    Short-circuit current (A) 8,16
    Efficiency of solar panel (%) 14,22
    Height (mm) 1375
    Width (mm) 670
    Depth (mm) 1,5
    Nominal Voltage (V) 12
    Width of cell (mm) 156
    Height of cell (mm) 156
    Number of cells 32

    what do you think chris?



    • Hi Rajiv,

      Maybe or maybe not. It depends on whether the dc converter puts out a fixed 36v regardless of what it is connected to, or does it expect to see battery voltage at the end of its wires? If it is a charge controller it will expect to see a voltage, which you don’t from the Torqeedo battery. Otherwise the two in series is simpler.



  23. hi chris

    i found a 12v to 32v, 3.4A, 109W step up power convertor regulator on ebay. it’s waterproof and i believe would work best to recharge the battery on the 1003. i plan to hook this up to the 12v house batteries. wish me luck

    fair winds


  24. hello chris

    i will check about the step-up-converter and i will use a external fuse.
    due the internel battery fuse is 4amps, would it be not wiser to use
    for example a 3.9 or a 3.8amps fuse so i can be shure that the external
    blows up always earlier than the internal one…

  25. hey jim
    can you send me the link of your converter?


  26. rajiv, i don’t know how to add a link but if you look on ebay the seller is “bubble.mind” and just describe the item as i did in the above email to chris and that should get you there.

  27. hi jim

    thanks, found the item and ordered it already, gonna try my luck and report back to you all.
    checkout the link which i gave above for the solarpanels, really cheap for the strength they have.



  28. I’m looking forward to reading a report on this dc converter, very keen to get one.

  29. got my dc step up convertor from ebay. tested it with a 12 volt power source and all seems good. i haven’t got my 1003 yet so we will need a report from rajiv to see how it works

  30. hi there
    could not test ether due i have the motor, the battery the converter but no boat…

  31. hi jim

    no, not yet, i have to do the wiring first.
    as soon as did i will inform you.

  32. hi there
    got my dc-dc stepup converter. testet it with 3 12-batteries wired in serial.
    unfortunately i measured more than 4 amps on the output side of the converter.
    so it seems that this configuration gonna blow up my internal fuse of the torqeedo!
    i will buy 2 flexible solarpanels put then in serial and connect them like this.
    i will connect batteries but directly so this will slowly charge the torqeedo battery
    also when the sun is not shining or during nighttime.

  33. that’s crazy i put one 12 volt battery hooked up to the in wiring and got 3.4 amps out.

  34. yes, i also put a 12volt source in but the 3 batteries in serial were drawing too much power.
    i do not know it this will work with the torqeedo battery. i want to try but i am afraid that
    the internal fuse will blow!

    • i just measured the open amperage without a battery. could you try two 12 volt batteries in series and check the amperage for me? i’m sure 32 volts won’t hurt that batteries short term. thanks

  35. yes, i tried with 3 12volt batteries in series. they were drawing more than 5 amps! from the dc-dc stepup converter!

  36. you have to check with a load on the converter. otherwise it will not show how much amps the destination is drawing

    • i’m not going to give up on it. chris suggested to put a four amp fuse inline. i like that plan and will try it. i’ll keep everyone posted

  37. Hi Guys, I find it odd that the open circuit current that Jim measured us 3.4 amps, as you’d expect, and yet Rajiv measures a higher current with a load. You’d expect open circuit to show a higher current than when there is a load. So it makes me wonder if it is actually a load that you have given it Rajiv? Is it possible that the current you are measuring is coming from the three batteries in series and flowing to the converter which has a lower voltage?
    How about trying what Jim suggests and hook it up with just two batteries in series? This will mean that the load that the converter sees will be at a lower voltage, say 26v, and the current will definitely flow in the right direction.

  38. rajiu i just looked at the old posts and i’m not sure just which step-up convertor you bought. early posts you spoke of a 4 amp 36 volt one that i saw too.

  39. jim, i bought two different ones: the first ist a 32v/3.4amps output and the second one
    is a 36v/4amps output. i tested the 32v one but perhaps you are right. i should try with 2 batteries only and not 3. the voltage should be about 29.6v or a bit lower. the stronger 36v one i did not tested because i am afraid of blowing up the internal fuse.

  40. i have another thing that we should consider. first i’m not asking or telling anyone to push the a safety factor but i know for a fact that when the factory says to “not have more than four amps of current” they have a safety factor built into that. is it one amp or more or less. i don’t know but i do know there is one.

  41. that means that we can target 4amps with no problem?

  42. hi there

    finally got my boat yesterday – a foldingboat called instaboat model “fisherman”
    very neat and nice aluminum boat.
    tested my torqeedo travel 1003 today for the first time with no “range-extender” (because no sunshine at all) and let it run for about 1.5h with 100w upto 140w. we were two persons on the boat. finally after 1.5h had still about 80% battey power and 2 times i gave full power just to test for about 1.5 minutes each. i am very pleased with that. one incident happend – after i returned home today i connected the battery to my goalzero system which harness our solar-energy during daytime, to charge the battery with solarpower. after 10 minutes the battery pulled so much ampere trough the cigarette-ligher adapter that it melted down! (the spring inside which makes the plus pole in front flexible got so hot that it melt the plastic-housing… have to search for a stronger one…
    loading now with the delivered 220v charge adapter.

    tomorrow will test it with “extending”- option. two solar panels in serial one 60w and one 50w. tomorrow we will have a very sunny day here in switzerland on the lake of murten.

    keep you informed guys!

  43. hi there
    tested the setup with two flexible solarpanels 50w & 60w wired in serial.
    i must say i am amazed. we crused the whole day on the lake for about 6h and
    in the end i had still 60% of batterypower. ok i must say that we crused with only
    2knotes but still not bad!
    best best

  44. Rajiv said, “yes, i tried with 3 12volt batteries in series. they were drawing more than 5 amps! from the dc-dc stepup converter!”

    I think the problem was that you connected the batteries in series, which would provide an input voltage of 36 volts. As the Converter is designed for an input voltage of 8-18 volts, you were operating out of specifications. Do you know what the output voltage was in those conditions. Try with the batteries in parallel or with just one 12V battery.

    Regardless thanks for the info. I will be ordering the converter and will try with my system.


  45. Alex Boucaneer

    Chris, I’m thinking of charging up my Torqueedo Travel 1003 battery with two daisy linked Powerfilm F16-3600 12 v, Amp 3.6, 60 Watt flexable folding solar panels, giving 24 volts, 120 Watts and still staying at 3.6 Amps.

    Does this sound correct and fine with you. I am new to this so passing it by you and your experience would help me a lot.

    Thank you Chris.


    • Hi Alex,
      What you are suggesting sounds good to me. Your are keeping nicely within the limit of 4amps for the power going to the battery. Sometimes under unusual conditions solar panels can produce a higher than expected output. I think this can happen with scattered clouds, which are bringing light to the panel, plus if the sun is unobstructed your also get the full sun. To guard against this rare possibility delivering too much power I would include a 4mp fuse in your wiring — this gives a protection against high currents, and is easily accessible. cheers, chris

  46. Alex Boucaneer

    Thats great Chris. Thank you.

    I am out in the tropics for this project. I might be working with Malcolm Moss of the Electric Boat Association, we will be in India.

    I will pass your shop details onto him and my friends. Is it possible for your shop to post to
    India. Thanks for the advice Chris.

    I owe ya a cold one or a bit of business. 🙂


  47. Alex Boucaneer

    Pardon me, I meant to say I will pass your details on to him. It’s always good for creative minds to have a chat and we are in the same kinda part in the world. Electric boating is Malcolm moss’s passion and he has been experimenting for decades.

    Always good to have friends that can help with advice about project’s or experiment’s.

    Thank you Chris.


  48. will a 36 volt 180 watt (5 amp @ 36volts max) panel with a 4 amp fuse as a current limiting device suffice, as i have one kicking around… it is within the open circuit limit of 58volts (as per the travel motor manual, albeit 20% above the 4amp max)


    Rated power (Pmax)1 180W
    Power tolerance +/-3%
    Module efficiency 14.10%
    Maximum power voltage (Vmpp) 36.00V
    Maximum power current (Impp) 5.00A
    Open circuit voltage (Voc) 45.0V
    Short circuit current (Isc) 5.2A
    Nominal Operating Cell Temperature (NOCT) 45.9°C/114.6°F
    Temperature coefficient (Pmax) -0.44%/°C
    Temperature coefficient (Voc) -0.33%/°C
    Temperature coeficient (Isc) +0.03%/°C
    Operating temperature range -40°C – +85°C / -40°F – +136°F
    Maximum system voltage 600V (UL) /1000V (IEC)
    Maximum Series Fuse Rating 10A

    if exceeding the 4 amp limit is an issue because my 4amp fuse idea unreliable or flawed somehow, perhaps i could cloak part of the panel???

    wouldn’t a 36volt panel be a better match than a 24volt panel for a 32volt lithium battery system anyway – or would it cause overcharge / over-voltage issues even though it is still within the 58voc limit?

    • Hi Greg,

      Your comment “wouldn’t a 36v solar panel be better than 24v anyway…” is key to this and its really a question of terminology. The link that you’ve included describes this solar panel as a 36v solar panel because that its maximum output. Its more common to describe this panel as a 24v panel because that is the system voltage that it would match with. That might seem confusing, which I think it is, so lets look at a 12v system to get a handle on what’s going on here. We all have this notion of 12v batteries, and 12v charger, a 12v solar panel. In each case we use these terms as a short hand way of describing the system. The actual voltage of each item varies from a neat 12v. A typical lead-acid battery will be about 12.8v when fully charged, and disconnected from any charge source. When being charged it may be as much as 14.5 volts, depending on which charge controller you are using and what you charge source is (such as alternator in a car). The voltage that is put out by a solar panel meant to charge a 12v battery needs to be able to supply enough voltage to charge the battery at the various stages of charge, such as the bulk stage, which might be set at 14.5v or somewhere like that. And it needs to be able to do this under poor solar conditions. To get 14.5v under poor conditions the solar panel needs to put out say 16v to 18v in good conditions, and that will be reported as the solar panel’s maximum voltage. So lets double the system voltage and so for a 24v system the solar panel needs to be capable of 32 to 36v. And so we see the solar panel you refer to here has a max power voltage of 36v. This is exactly the solar panel voltage you need for this task. The problem of these guys describing it as a 36v solar panel is that someone with a 36v system (three 12v batteries in series) might assume this solar panel would be good to charge these batteries. But clearly this is not the case. I expect most suppliers would describe that solar panel as a 24v panel.
      I think it would be fine with a 4amp fuse. And in my experience its very unlikely that you will see that power if the panel is mounted on a boat. Its angle will almost never be the right angle for the sun so the output will typically be lower. When using it ashore and if you deliberately align it to the sun you might then see its rated output. So just be careful when you set it up ashore. If you have a clamp meter you could measure the current under various conditions and get to know whether its likely to exceed the limits.



  49. Chris, may I ask another question?

    Can the lithium battery be charged at night by a marine wind genorator that designed not to exceed the 4 amp maximum and fitted with a 4 amp fuse?

    Also can the solar panels charge the spare battery in the daytime when removed from the motor. ie. sitting on a beach with solar folding panels and the removed lithium battery?

    Some people say it must have to go through the computer built into the outboard to charge. I am not sure of this.

    Thank you.


  50. Hi Alex,

    A wind generator would may not be suitable because they need to run under load at all times, and if the fuse blows you may damage the wind generator. As well the voltage from a wind generator changes with RPM and may easily exceed the voltage required. What about using another battery as a buffer, and it could be a lithium battery for lightness? This would be 12v and you can charge it with wind or solar and use it for other tasks around camp, such as lighting. Just connect direct to the Torqeedo battery and it will trickle charge it.

    A solar panel can charge the battery when it is disconnected from the motor. All the charge control is done in the battery.



    • Thank you so much Chris. That is great advice. You have certainly sorted out what I was reading posted to me on a yahoo group I belong to. Thanks again.

  51. many thanks chris

    the standard charger (Part# 1127-00) that comes with the 1003 is rated at 12vdc 40 watts 3.3amps

    the torpedo fast charger (Part# 1131-00) for the 1003 is rated at 85 watts yet indicates no current or voltage parameters in its literature.

    out of curiosity, have you one of the 85 watt fast chargers on hand to let us know what voltage and current it is rated at and/or capable of delivering?

    I am assuming it is a high enough voltage to maintain the “max 4 amp” rule @ 85 watts, but if it is over the previously suggested 16 volt threshold for kicking the input into the solar charging stream – how does it obtain maximum charge with a practical voltage limit that is under the lithium’s 32 / 33 vdc? Or is it (the fast charger) indeed rated at 32vdc???

    thanks again for the the awesome support/

  52. Have someone got the fast charger ?
    Can some tell us what voltage it gives?

    It could be 32VDC or 24-60V with currentprotection at 4A/85W..

  53. hi Greg, yes, interesting question. I have not seen the fast charger, and none are confirmed to be in the shipment, so I don’t have an answer for that. I wonder if they are released in Germany — perhaps someone there knows the spec?

    cheers, chris

  54. I have fast charger 85 watts.
    The voltage 35.75 v.

  55. Hi again from England.
    I have ordered a fast charger…why have a slow one when you can have a fast one?
    What has really surprised me is the ease of charging using a cigar lighter plug direct to the Torqeedo battery. I made up a plug, lead and Torq battery plug and have used this very successfully to recharge the Torq battery. It trickle charges and appears to put no strain on the ships batteries. No need for an inverter. Electric outboarding has got a whole lot easier.

  56. Or this one:

    Delivers 24v and 4,1A
    Since it is said above that there should be a little margin ath the 4A the 4,1 should not be a problem?

  57. Hi from Missouri,
    A follow up on my project. I used 2 Torqeedo Travel 1003L and 1 Torqeedo Cruise 2.0 in a 340 mile solar boat race on the Missouri River. Didn’t finish the 340 miles. But have set a record of 188 miles in under 31 hours for the event.

    I’ve been watching this site to get some hints and ideas on how to devise a usable long range pocket cruiser using the Torqeedos. This race happened to come up in my back yard so it was an opportunity I couldn’t pass up.

    Despite trying things I learned here, elsewhere and by trial and error I determined that there was no way I was going to overcome the slow charging rate of the Travel batteries. I tried the DC voltage converters. They seemed to work but there seemed to be some interaction between the electronics in the Torqeedo battery and the converters that prevented them from actually getting a meaningful charge to the batteries. I had 4 of the converters and they all eventually failed. No longer work at all. I had some success connecting 4 30 watt solar panels in a series/parallel arrangement to achieve 108 watts input to the battery. 32 volts at 3.4 amps. But the motor only showed an input of about 30-40 watts. ?? So even though I had two Travel motors and 5 batteries, I concluded I would not be able to sustain power long enough to make a serious effort in the event. The solution was the Torqeedo Cruise 2.0 and the Torqeedo Power 26-104 battery. Matched with over a kilowatt of solar and a robust charge controller I was able to convert sunlight to enough electricity to run the boat during the day and store enough to keep going at night. Yes, much more expensive than the Travel motors. But the capability is so far beyond what the travel can do. I had enough power with the two Travel motors, but not the capacity to keep them charged for continuous use.

    Below are some video links. I also have a PDF file with details of the boat configuration, photos, charts, etc. but I don’t know how to attach to this post. So if anyone is interested they can request it by sending me an email. KykCat@aol.com ask for the “2014 e340 report”

    Here are some video links.





  58. Hi Chris,
    I’m pretty sure this combo should be ok, just want to run it by you.
    1003s Battery and a CIGS Solar Panel 24.7v(Vmp) 90w(Pmax), 3.6 Amp (Imp); 33.6V(Voc)open circuit; short circuit current 4.3 Amp(Isc). I will of course put a 4 amp fuse on it for any peaks and an on off sealed toggle switch.

    • Hi Murray,

      Its good that you checked because thats not gonna work… the voltage is not high enough to charge the battery. Keep in mind that the nominal voltage of the 1003 battery is 29.6 volts and the final charge voltage is 33.6volts. At Open circuit it voltage is 33.6 but under load its voltage is 24.7, which is well below the battery’s nominal voltage. You may get charging when the battery is nearly empty but as the charge level increases the ability of the solar panel to deliver power will progressively decrease and at some point you will get practically no charge. I suspect very soon after charging begins.


  59. Thanks Chris, it was going to be a loan panel to see if it worked, then buy it if it did. You’ve saved me a lot of effort.

  60. Hi Chris,
    how about 2 of the same panels in Series?

  61. Hi Chris,
    I am not sure if a problem has occured with the site, but I have put a few responses up over the last few days and they have not appeared.
    Should this one, can I ask your thoughts on using 2 off the above mentioned panels and how I might regulate the output so it does not over charge

  62. I have a 130 watt 24 volt (nominal) solar panel. Vmp is 35.6 volts and Imp is 3.66 amps. This would appear to be an ideal panel for charging the 1003 battery directly. Is this a fair assumption? I don’t own a Travel 1003 but I might consider it if the battery can be easily recharged. Also it would be nice if the four amp internal fuse could be easily changed by the owner. Thanks.

  63. Hi Guys, have the 1003 and have tried hooking up 80w solar panel (actually 2 x 40watts hooked up in series) which puts out about 38-40v at about 2.8w. on an average day. However when I plug it into the battery I do not get any charging light. The tiller display also does not show any charging status at all. (Battery is about 90% charged)
    Just a note, I plugged in the AC Adapter charger that came with it and while the red charging light blinks the information display on the tiller does not show any charging info.
    When I am running the motor and have the AC adapter plugged in (I have a portable AC battery / inverter combo) the red charging light turns off. Also in charging info is displayed on the tiller info panel.
    In fact I have never seen the charging indicator show up on the LED display panel on the tiller. (I know its there as it shows up when you first power on.)
    Is this normal or is there something wrong with my battery. The battery still charges normally with the AC adapter.

    • Hi Larry, Thats odd. Another indicator is that you would see a change in watts being drawn from the battery. Say you are running the motor at 60 watts then when you plug your solar panel into the battery the power should drop to around zero. It makes me wonder if your jack plug is connected ok and/or if it is the correct plug? Are you seeing the output voltage at the plug? If that is good it makes me wonder if you have blown the solar charging fuse in the battery. Is there a possibility that you have applied more than 4 amps at some point? The AC adaptor charges through a different circuit even though it is the same plug.


  64. Dear Chris,
    Thank you for the fast reply. Checked the output plug and its definitely working. I guess its possible we blew the solar fuse as I think our setup can theoretically put out more than 4 amps on a perfect day.
    I am guessing that fixing or checking the solar fuse is something that I cannot do my self and I will need to send it back to the factory for a warranty repair?
    Thank you for the heads up about the power draw, I will check to see if we get any type of drop in watts when plugging the solar charger in. Hopefully I will.
    Thank you again!

  65. Hi Larry and all,

    I think it is good to have an external fuse in line with any solar attached to the battery. Good conditions can cause short term peaks, and at least this way there is half a chance that the external fuse will blow thus protecting the inside one. A quick check on google shows that we can get 3.5 amp fuses and this would allow a little headroom. I would rather change an external fuse now and again that be faced with the possibility of having to return the battery to service centre for checking and replacement of internal fuse.

    Good luck with it.



    • Hi Chris –

      I’m having the same problem as Larry. I built a 72 watt, 24 volt, 1.9 amp panel using 4 Aurinco 18W panels in a series / parallel setup.. In full sun, the measured Voc is about 44 volts, the Isc is about 1.8 amps. I can’t see how this panel could produce 4 amps to blow the solar charging circuit. Is there any way to check that fuse?

      The battery still charges fine on the 12V house batteries using a home-made cigarette lighter adapter cable.


  66. Hi friends,

    I am a crocodile researcher from India doing research about different varieties of crocodile. Recently I bought a Travel 1003 motor for closely monitoring this species. Later I understood that if I have more range in battery I could get longer range to more sufficient data for my studies.

    I have been researching on all the topics in range extension and noW I am totally confused . The range extension I can charge the torqeedo from 12V battery. Please provide the DC-DC Converter specifications for charging the empty torqeedo battery from 0 to 100 % in about 5-6 hrs.

    Please specify output voltage and current of the dc-dc converter. I would like to get answers from those who have tried DC-DC CONVERTERS for range extension.

    Please help me

  67. This has been wonderful reading. Thank you all. Please forgive a basic, simple question. If I have the right solar panel can I just leave it plugged into the motor day and night? I get the 3.5A fuse. Do I need a diode so the panel doesn’t drain the battery at night?

  68. Hi,

    Sorry that I was not able to update my experience with torqeedo 1003 range extension with a dc-dc converter with a constant current and constant voltage output of 33 VDC , 3.5 Amps.

    Unfortunately the LED blinking that denotes charging has started was not there. Later understood its not charging.

    So I connected directly from 12 V battery with 4 A fuse. The LED started blinking shows that its charging.

    I hope the output voltage from the charger is checked by some system before it allows current to flow into torqeedo battery.

    I thank all of you guys especially chris who helped me in this problem.

    Someday we will surely crack the torqeedo charging in the same way as German enigma radio interceptor was cracked.

  69. Hello again,

    I had some questions 2 years ago about twin 1003 and solar charging… Back then something came in between , project stopped.
    I’ve picked it up this year, have now a single 1003 with a honwave T40, 140cm high Bimini where I’ll put with a help of NOA rail holders a 100W solar panel…
    I haven’t tried it , will assemble for the first time this month and will use it during our vacation end of July…

    The interesting new thing is the new battery… The 4A limitation is gone, it limits the current by it self. I’ve spoken with Torqeedo, Holger Reinhardt , asking about my 12V->30V booster charger with current limitation of 3.5A and he said that without the current limitation, it should work. Now, this applies only to the new batteries (with USB adapter) , produced in 2015… Has also a new fast charger and they are not compatible with the old chargers…

    I will purchase an additional battery, will have two 12V charging cables and an 80Ah 12V battery in the Minn Kota power center.

    I will post my experience with them, I’m very curious about the range with this setup.

    But the most important thing is this change regard the 4A limit and fuse.

    Chris, Have you tried the new battery?


    • Hello Faraday,

      Thank you for your post. Could you please provide your experience with solar panel and range extension? What concerns the new battery – I own travel 1003 with the new battery and from mains power supply using original fast charger it charges fast enough – I think 4-5 hours – did not measure exactly. However I am not sure if new inbuilt controller that adjust current automatically with the voltage range of 9,5 to 50V is well aligned with original torqeedo sunfold 50w solar panel. Under perfect conditions it would charge and would reach output of full 50w (measured when motoring), battery was charged even during total overcast – indicator of the battery was blinking. But I have faced issue when charging from solar panel under changing conditions – charging started in perfect sunshine 2p.m. south of France, but it stopped 4p.m. when sun was slowly covered by high light transparent clouds (mackerel sky) and did not resume even trying different panel positions, but still directly exposed to the sun which was well visible through the uniform film of clouds and was well above 45 degrees from horizon. Solar panel was not shaded. I am surprised since most of the solar panel producers would confirm that under unfavorable conditions solar panel would generate power, and the only issue is partial shading of crystalline cells. Therefore I suspect internal torqeedo battery controller, but since I am not physics, I do not understand which of the parameters is causing cut off in charging. The description of newest battery contain strange expression for charging from DC – “The required minimum current is 4A”. Solar panel is not DC, and if I understand correctly both circuit and current vary from solar panel, but that is controller’s function to adjust properly. I appreciate if anybody would have any ideas or similar experience.

      • Hello Sir,

        Sorry for not checking in earlier.
        I was charging with the solar panel a 12V battery and using with a dc-dv booster (36V) and torqeedo 12V battery charger to charge the torqeedo. I was getting in ca. 100W. Not sure the 12V plug is designed for 100-120W more for 50W so it gets warm.
        I had another issue, my son does not like the speed 🙂
        With Honwave T40, this is a very underpowered setup.
        This year Torqeedo anounced a same size but almost double capacity bateries, but i will face a similar problem.

        This year i’ll try to think through my setup and what to do with it. The T40 is stable, enough space, but it’s for a 20HP gasoline, lets say at least 10HP… 1003 can’t compete. The bigger ones need batteries and they are very expensive or very heavy.

        The game with the solar panel above the bimini is also a problem, as soon wind starts, its probably breaking you even further. The bimini alone if the wind is bad, is a killer at 300-400W power.

        These are mine findings


  70. Does anyone know what is the maximum voltage that the <2014 battteries will take? We know that the 36v * 3,33A (120 W) works fine, but would the 36v * 3,9A (140W) work? Or even a 50v * 3,9A (200W) ? I am about to order a custom-made changer and wander if I should push the limits of the torqeedo fat charger (36v * 3,3A) even further …

    • Hi Nikos,

      You have two questions wrapped together there — maximum voltage and maximum current. Lets start with voltage… the actual charge voltage depends on the state of charge of the battery at the time. When the battery is fully discharged the voltage is around 25v and so the maximum charge you could get into the battery, at say 3.9 amps, is 3.9 x 25 = 97.5 watts. When the battery is fully charged at 33.6v and 3.9 amps the maximum charge rate is 33.6 x 3.9 = 131 watts. Even if the applied voltage is 50v, it is the battery voltage which will determine the charge rate. You can see from this that increasing the voltage above 33.6 has no effect on charge rate. Any voltage high than the battery voltage is wasted. Regarding maximum charge rate, I think it is risky when you get close to the limit, such as 3.9 amps, because your solar panels my spike higher than this under ideal conditions. Ideal conditions can be a cool cloudy day and when the suns burst through from cloud cover your solar panel can produce a burst of power higher than the rated output. I would be sticking to the 3.3 amp panel just to be sure.

      You mention that you are getting a custom made charger. This may prevent your system from working. The torqeedo battery has a charge controller built in which means you can directly connect your solar panels. Charge controllers typically need to sense battery voltage to work, and with the Torqeedo battery, your charger will not be able to sense the voltage, and so may not even begin charging.


      • Hello Chris,

        Sorry for the late reply. I am too interested in conditions under which fast charging of the old Torqeedo Travel battery is possible. As I understood from your previous posts the input voltage of the power supply should be at least 33,6V and supply current limited to 4A. But what about higher voltages? Please correct me if I am wrong: as long as the open circuit voltage of the DC power source is below 60V and the output current limited to 4A there is no risk to damage the battery circuit. The actual battery voltage will depend on the state of charge and charging current. I assume there is no direct connection between the charge socket and the battey cells also with the high voltage charge channel. Is the charging process controlled by the battery circuit also in the case of the high voltage charge channel? If yes, the power supply voltage shold be higher than 33,6V to compansate a voltage drop of the controll circuit (i.e. internal switch).


        • Jernej, you now need to be sure which batteries you are using. The new batteries will take a range of voltages and the shenanigans we had to get up to as described in this blog and comments are no longer needed. with the new batteries you can connect any solar panel from 12 to 50 volts. be careful not to go over voltage. but to get back to your question, assuming you have the original batteries (part numbers 1413-00 for Ultralight 1144-00 and 1145-00 for travel), you need to have higher voltage than what the battery state of charge is, which can be up to 33.6, and anything higher than this up to 60v is ok but wasted. any voltage higher than the battery voltage is wasted. on the other hand the new battery has an internal voltage converter which adjust the voltage to what is needed by the battery. in the case of the new batteries, higher voltage is an advantage because you can provide up to 4 amps. I really need to update this blog to account for the new battery specification. your last question, does it need to be higher than 33.6 to compensate for losses. well only if you need to fully charge the battery. for the use suggested in this blog, of range extension, chances are your battery will not be fully changed when you are doing this, and so as long as your solar panels are putting out higher than the battery voltage then you will be charging ok.

  71. Hi Chris, thank your post ant important discussion. I am a new owner of Torqeedo Travel 1003, which I use on my 12 feet porta-bote. I like the concept and performance so far. And I am looking for range extension using solar panel. Actually I have already ordered the original one of Torqeedo http://www.torqeedo.com/en/products/accessories/charging-equipment/solar-charger-50w-for-travel/1132-00.html . Nevertheless after reading whole topic and the answers I am still trying to figure out are there any better alternatives – I refer to solar panels. The market of fold-able, semi-flexible, rigid solar panels for boats is growing and the prices become more affordable, so why not to use something even better and probably cheaper. I simply ordered original one as I wanted “plug and play” option without any additional controllers or similar gear. Nevertheless Torqeedo says that the battery can be charged other solar panels, and the battery adjusts to the panel power. I am not so good in physics, so I get confused by some of your statements and what is said the manual of Torqeedo Travel 1003. In your original post you have stated “You can use a Torqeedo solar panel or any 24 volt solar panel with the right connections. You can even use two 12v panels in series, or as we did on the zodiac trip, four six volt panels in series. Just be sure that the maximum output does not exceed 4 amps. Any more than this will exceed the circuitry of the battery’s built-in charge controller and you’ll blow an internal fuse which requires return to service centre to repair”. Manual of Torqeedo says: “7.4.3 Charging the batteries from the on-board batteries: It is possible to charge the battery from any DC voltage source within a range of 9.5V … 50V.The required minimum current is 4A.” and “it is also possible to charge the battery with solar panels with an open-circuit voltage of up to 50V. For charging please use a wire cross-section of at least 0.5 mm 2. In that case the battery will dynamically adjust to the panel power”. The last statement does not say anything about the current. I appreciate if you could provide some explanations.

    • Hi Julius, Thanks for your question, which reminds me it would be helpful to update the original post. The latest batteries from Torqeedo have a new charge circuit, and the comments in this thread generally relate to the old batteries. The new ones can take any voltage from 9.5v to 50v and the source needs to be able to supply 4amps to get the best results. A significant change is that the current is now limited internally and so you don’t need to worry about this by external control. In the old batteries this control was managed internally for low voltages, such as when charging direct from a 12v battery, but you needed to manage it when charging at voltages above 30v. If your battery has the USB charging option it is the new type.

      • I did the cost benefit exercise exploring solar for range extension and determined that the investment needed to achieve the equivalent benefit of having a second battery on hand required a solar panel capable of recharging at the maximum rate (approx 150 watts) would practically require a larger panel feeding a 12 volt deep cycle battery connected in parallel to the 1003 to address cloud cover and other sub optimal charging conditions and accepting a discharge model that meant operating the motor at no more than 150 watts (average) above the maximum calculated (solar independent) range required for the day’s boating. All this infrastructure for an extra 150 watts of tiller power did not make sense, so I opted for a second battery – knowing I can exhaust number 1 battery at any discharge rate and still make it home guaranteed using number 2 plus I am not fighting for space with a solar panel aboard and the weight of an old tech deep cycle battery that is significantly heavier than the high power density 1003 equivalent. Notwithstanding the need for remote area power operation over multiple days, where there is simply no substitute for solar.

        Boating is much more fun now that I can apply thrust with impunity while potentially doubling my effective range if necessary…

        Greg 🙂

        • Hi Greg,

          Yes I think you’ve nailed it. For most cases a second battery will be best. Its only for multiple day remote area use that the solar panels come into their own. Even then it has to be many days in a row to beat the flexibility of spare batteries.



      • Hi Chris, Thank you for the explanation. That is what I have finally understood from the manual of Torqeedo as well. Yes, my battery is with the USB adapter. Last Saturday I have tried 50w torqeedo solar panel. The day was perfect for that – completely clear sky, perfect sunshine (south of France), morning without wind, afternoon with light wind – 3-5m/s. What I understood from the computer display is that depending on angle solar panel was producing 35-50w of power. I am not sure if it really works this way but what i understood from charging indicator is that during motoring power generated from solar panel goes directly to motor, not to the charging of battery. At certain moments computer display was showing 0-19w consumption and with this power I was able to reach 2-2.5km/h speed. I believe mainly with the power generated by solar panel – battery was not discharging at that speed – showing no limit in the range, o showing the range of 45-70 km remaining when power consumption varied from 0-20w. Usually to reach the speed of 2.5km/h without solar panel the power consumption from the battery was around 50w. Charging indicator (blinking red) would switch on when motor is stopped. The solar panel has charged 520Wh battery from 78% to 85% when stopped for 3 hours on the beach and solar panel exposed to the midday sunshine. I did not perform any calculation but I suspect that use of the power generated by solar panel is more efficient by direct motor consumption than for the charging process, especially when the battery is not discharged a lot. I was told by local torqeedo dealer that charging efficiency decreases when battery is almost fully charged because some power is lost due to increasing voltage of the battery. Original solar panel is 12V. Please correct me if my observations and statements are not accurate.

  72. It would be interesting to know the amount of charge per hour that the new battery will accept, if it will now take a wide range of voltages and prefers >4A. It sounds like it is no longer necessary to use an external dc/dc converter (for example the 12V to 32V 3.2A version that I use on my old battery) to get the shortest possible charging times when charging the Torqeedo battery from another battery. It also sounds like the 4A external fuse is now redundant with the new battery circuitry.

    This raises the intriguing possibility of bringing aboard other lightweight lithium batteries to increase range in countries with less than perfect sunshine, such as the UK. For example, I have several lithium batteries for powering electric bikes that might suit. They operate at around 28V and 8-18 Ah, depending on their age. If the charging times were fairly short with these plugged into the charging socket, it could increase the motor’s range significantly.

  73. I have received and important answer from Torqeedo customer service in Germany answering my questions and concerns about solar panel I have expressed in my post of 05.10.2015 (comment/question to Laszlo Faradays’ post). Just wanted to share in case you find it useful. Probably it may answer the questions about using different solar panels (I remember that there were comments in this thread that “charging indicator is not blinking and battery is not being charged”). Answer from Torqeedo:

    “Unfortunately there is a bug in the software of the Travel Battery. Below a certain current it will not show the charging status and the % display will not increase.
    The solar charger works: if you switch the display of the travel to volt you will see that the voltage is increasing. We are are working on a software update for this.”

  74. Dear Chris,
    Recently I read that Solbian sells a system ready to recharge batteries called
    72W Solbian All in One SP72. It costs around 600€.
    They call it has a MPPT + booster and adapts to all kind of batteries.
    More details:
    Anybody has used it with Torpedo 1003 battery? Is it possible to plug it in directly?
    Any experience?

    • Hi Bepi,

      The problem with such systems which have intelligence to charge at the right voltage to match the battery is that it cannot have direct connection to the battery. Inside the Torqeedo battery is also some intelligent software that is expecting dumb solar panels that will simply provide a source of power, which is then managed by the Torqeedo internal charge control. products such as the solbian need to detect the battery voltage so they can perform their voltage control, and that is not detectable on the Torqeedo battery. I did not actually try the solbian solar panel but I believe the result you will see is no connection. The new Torqeedo batteries do this kind of thing internally so there is no need to spend this extra money on a smart solar panel. Just get a simple dumb one and let the battery do the charge management.


  75. Hello chris ı have 50w 24v solar panel 2.8A open circuit 30v. when ı charging of my 1003s battery the red light is not flashing and itsnt charging. Ty for responding.

    • Hi Ibrahim, There is an internal fuse on the solar charging circuit which may have blown. The solar panel you have selected should be fine, but clearly something is wrong. Your solar panel should not have blown the fuse. Have you connected the tiller while charging? It will display a “charging” sign, and you can see the battery charge % changing as well, if it is charging. The fuse cannot be changed by the end user because opening the battery would void the warranty.
      Have you checked that the wiring of your solar panel is correct, that is, with positive on the centre pin?

  76. İbrahim Güçlü

    The wiring is correct, Ive tried with tiller and without tiller it didnt changed. you can see to the link.



    And that is my panel pic..


    Fuses werent blown I ve checked, dont worry my warranty has expireed


    • The fuses you show are the main power fuses from the battery to the motor. The fuse that can blow because of high current in your solar panel is a small fuse on the board. You show two solar panels. are they two 12v panels in series to produce the required voltage? or two 24v panels in parallel.

  77. Hi

    On the latest 1003 batteries where it is possible to charge the battery from any DC voltage source within a range of 9.5V … 50V, can you leave the battery permanently connected to a solar panel or external battery?

    • The latest batteries do have a more useful range of charge source and the interested thing is that it is internally regulated to 4 amps. In the case of solar panels it will take what it needs up to 4 amps, and from a battery it will take the 4 amps, so its important that your external battery have the capacity for that. Keeping it connected is possible but not the best for longevity. Lithium batteries last longer if kept at a state of partial charge, around 50%, than if they are fully charged.

  78. Hi Chris

    Many thanks. As I have to leave the the boat for long periods at times I guess I will have to put in a relay with a current detector to disconnect the PV panels.


  79. Hello Chris,

    Thanks for this excellent forum and your generous assistance.

    I just ordered a new 1003 (usb). I have some panels here from when we were building the house and off the grid. The specs are:

    Min Power Voltage 18.7V
    Max Power Current 7.75A
    Short-circuit current 8.37A
    Open-circuit voltage 22.3V

    I’m in Arizona so solar is plentiful.

    My (limited) understanding suggests I can connect this directly into the solar charge socket on the new 1003. Is there an advantage in running two panels to double voltage? Perhaps too many Amps…

    The boat is a Hobie 16 we want to use as a solar lake cruiser while being able to switch back to sailing without much effort. Was thinking of building a removable mount between the front hulls to carry the solid panel(s).


  80. There seems to be a general misunderstanding on the site. The manual for 503/1003 states that the minimum current to charge the battery is 4A, not maximum. There is no need for an external charge protection circuit unless the voltage of the supply has the potential to go out of range. A 2.8A open circuit solar panel will not reach the threshold current to enable charging. Place two such panels in parallel and you may have a chance.

    • We now need to be aware that the latest batteries from Torqeedo have a different specification, as Humphrey points out. Its not a general misunderstanding on this site, its that the batteries are now different. What is changed is that the charge current changes from 4A maximum in the old batteries to 4A minimum in new batteries. The new requirement of minimum capability can be misleading in a way. it means that the equipment needs to be capable of minimum 4 amps without overloading it. You can use solar panels because they will just put out whatever they can, and it can be less than 4 amps and it will still work. The trouble with connecting some devices such as the old style fast charger to the new batteries is that that charger cannot maintain 4 amps without overheating. If you try to use this charger with the new batteries it will work for a while, but it will overheat and fail soon. This applies to any other equipment that you attach to the new Torqeedo batteries. dc-dc converters are internally limited to a certain output and so should not be a problem.. but power supplies and chargers not meant for these batteries will fail.

  81. hello chris. thanks for having this site. i have an argonauta 28 trimaran designed by dick newick. it weighs 2500# and and moves at 2.5 to 3 knots in 5 knots of wind. i’m currently installing a torqeedo 1003 as my auxiliary power. i use the boat in the bahamas where the trades winds blow most of the time. i have three 100 amp hour lithium ion batteries for house power and i plan to carry a spare 915 battery for the torqeedo. the boat has 380 watts of solar panels and two rutland 504 wind turbines. How should i charge the torqeedo batteries? With the 12 volt cord or the 90 watt charger through an invertor? How many watts will the 12 volt cord put into the batterys? jim

    • Hi Jim,

      The new batteries will take 4 amps from whatever charge source you supply, and so for a 12v source you will see 12 x 4 = 48 watts. This is pretty slow and would take about 20 hours to fully charge a 915 watthr battery. If you want to charge faster use an inverter and 90 watt charger but you’d lose more energy that way in the conversion from DC to AC and back again to DC. MY guess is that most times overnight charging on the 12v would be enough, and only use the 90 watt charger if you are in a hurry.

  82. thanks chris. i was thinking along those lines but i needed to hear it from someone in the know. the trimaran looks really good with the panels and turbines and should move great with the torqueedo. i sailed engineless with a monohull years ago and it’s fine once you accept that you done have one. i’ll send a picture. jim

  83. chris do i understand correctly that the new batteries on the 1003 would charge straight from a 24 volt source battery bank at four amps too ? 24 volts times 4 amps totaling 96 watts?

  84. Hi Jim, Exactly right. And this more or less what you have with the charger that comes with the 1003 these days. It puts out about 24 volts.


  85. well chris. i think i’ve gone in a full circle with my questions. i found a 12 to 48 volt, 3 amp (144 watt) step up converter with over voltage, under voltage, overload, underload, and short circuit protection. i don’t see how it could hurt my torqeedo 915 battery and still get a good fast charge from my main batteries. what do you think?

  86. found it. after my last reply and hours online. i found a laptop convertor 12 volt to 24 volt (100 watt) built to recharge your laptop lithium in battery from a 12 volt source like the plug in in your car. the only problem i see is the jack for the torqeedo might need to be changed. google “powerstream laptop converter 12 to 24 volt 4 amp 100 watt”.

  87. i just ordered two “NBPSU100CH 100 watt adapters” i sent a number of emails back and forth with torqeedo and they said “it should work fine”. i found them at powerstream technology on line. they have both the jacks and the cigarette lighter plugs attached. they are located in Utah, USA. so now i can charge right from a battery at 100 watts rather than 48 watts that the 12 volt cord does. no more gasoline outboards and gas cans.

  88. Hi Chris
    I have just ordered the new ultralight 915w battery from you guys to use with the Hobie Evolve set up. Very excited to try this out. Thanks to your replies on this forum almost all of my questions have been answered. I have a Hobie Tandem Island (sail, pedal, paddle or motor trimaran) set up with 2 flexible 200w solar panels (400w in total) charging a 12v 120ah Lifepo4 lithium battery. This has been powering a Watersnake brushless 12v 70lb trolling motor. Seems to work ok however the Watersnake at 600w is slower than the Torqeedo at 400w. Plus the motor alone must be 5kgs heaver than the entire Torqeedo system. I plan on doing some big trips (Murray River, Fraser Coast, Whitsundays) where i could be out on boat for weeks. I plan on retaining my current solar battery set up & will use the Lifepo4 battery to charge the Torqeedo battery. I will use a small 240v inverter to power the standard 90w charger as a back up only. I would like the main charging duties to come from a dc-dc converter 12v to 36v at 4\5 amps delivering the max 120w. Which leads me to my question. Do you know of a dc-dc converter or similar product that will do the job? Cheers

    • Hi John,

      Thanks for your question. Thats some pretty cool trips you have in mind. With any of these kind of projects its always worth running what my friend Marv always called “the drudgery of the numbers.” With 400 watts of solar panels to charge you battery I think you could expect about hald this, say 200 watts, as the peak output that you might see from these panels under the usual conditions you get on a boat. That is, not ideal orientation, and constantly varying orientation, regular shading from rigging and sails, and so on. One way or another you can probably expect to get 3 times the namelate capacity of the panels on a nice day. Less on cloudy, rainy days, and maybe occasionally better on ideal days.
      You could expect to get about 1200 watthrs of charging on a nice day. Your LiFepo4 has a capacity of 120x 12 = 1440 watthrs. Say you allow to discharge it to a maximum of 90%, so you could count on a usable capacity of around 1300 watthrs. This is pretty close to the capacity of the Torqeedo battery, so it would be possible to completely charge the Torqeedo battery from empty if you do have the litium battery fully charged.
      Where I am going with this is to ask the question how often would you be in the position where you need to charge at 120 watts? And would the 50 watts you could expect by charging directly from you lithium battery be enough anyway?
      Your lithium battery would normally be around 13 volts and so would deliver around 5o watts to the Torqeedo battery simply by plugging it in directly without needing a dc-dc converter. (thats 13v x 4 amps charge rate)
      If you can keep the Torqeedo battery attached to the lithium battery continuously in 24 hours it would transfer the 1200 watthrs that you could hope to get from the solar to the Torqeedo battery. Any faster than this would not be possible because there is not enough energy harvested each day to do better than this.

      Suppose you are on your adventure and arrive at the campsite for the day with the Torqeedo battery empty, using the last bit of power to arrive at camp, and the lithium battery is full from the solar charging, say 6pm. I think this is optimistic but lets go with this to start getting a sense of the numbers. Overnight you can keep the Torqeedo battery attached to the lithium and proceed to charge it. Lets say you are ready to leave camp at 8am, that is after 14 hours, and you would have added 700 watthrs to the Torqeedo battery. Not fully charged, but about three quarters full. Maybe there is a little sun hitting your solar panels to begin charging the lithium battery. It this point it is close to empty (or even completely empty of you intend to use this battery for charging your phone and other uses at the campsite). But anyway, even just supplying the TQ battery it would be down to 700 watthrs, or about half full.
      During the day until 6pm you will harvest another 1200 watthours from the sun, and be able to deliver 500 watthrs to the Torqeedo battery. (thats in the 10 hours from 8am to 6pm). If you used all this energy to get to camp the Torqeedo battery would be empty, and the Lithium battery would be just full. (it started at 700 watthrs and you added another 700 bringing it full again).
      As it turns out your size of solar panels, and lithium battery capacity, and charge rate, are all in balance on a nice day. I’m not sure that having a dc-dc converter would deliver much advantage for multiday trips. On rainy days you would run a deficit, and if you used any of the charge from the lithium battery to run other devices you would also have less power available than you could deliver to the TQ battery in 24 hours.

      How you intend to use your setup may be different to what I describe and you may indeed need the faster charge rate. I have used Snaptec inverters http://www.snaptec.com.au/gb30-1230.html
      the output voltage of these units is adjustable by about 10% from nominal. I have used them in series to get the power I needed. I have a couple here that I had on my yacht for 6 years and now in the shed but still working fine. I bought them in 2008.
      There are many more options available these days and you can probably find a unit that will deliver what you want.

  89. Hi Chris. Sorry for late response. I did want to thank you sincerely for your incredibly informative & detailed response. I actually wrote a long winded reply back in March & a power outage lost it all. I think you were bang on with just going with the simple 12v charging option delivering a full charge over 24 hours. I hadn’t considered this. With Covid & winter I haven’t had the opportunity to put the solar panels to the test. I have just purchased a 22ft trailer sailer & will be using the same solar panels on this boat. I will probably sell the Hobie however my big trip plans remain the same only I’ll be a lot more comfortable. I’m currently evaluating the purchase the new Torqeedo 1103 outboard motor for this boat. Once again thank you for your help. Cheers

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