Sanctuary Cove is a waterside community in southeast Queensland well known in the boating world for their hosting of one of the best known boat shows in Australia. They are now setting new standards with their adoption of electric outboard powered vessels for their security patrol.

The usual solution is to use a dc-dc converter to step down the voltage from 48v to 12v. You . . . → Read More: Mixed voltage loads and charging]]> What do you do when you’ve got mixed voltage loads in your system?  Such as a main drive battery of 48v and smaller loads such as radio, chart plotter and so on at 12 volts?

The usual solution is to use a dc-dc converter to step down the voltage from 48v to 12v. You have to be careful to make sure that the dc converter can deliver enough power for the combined load of all the 12 volt devices.  And if you have a big load, such as a 12v anchor winch, it can be expensive or difficult to find an dc-dc converter powerful enough to handle the load.

Solar Converters Inc of Canada have an innovative solution to this problem—and they call it a battery equaliser.  Here’s how it works…

What if you tapped 12 volts of one of the batteries in the string that makes up the 48v pack—then you’d be able to take as much current that the battery can supply.  But the difficulty then is to recharge this battery to correct level to match the others in the string. And this is where the battery equaliser plays its part.

A regular dc-dc converter produces a set voltage.  But in this case the voltage of the battery being charged is moving target.  It needs to be matched to the other batteries in the string. The battery equaliser, instead of producing a fixed voltage, produces a voltage of exactly 1/4 of the input voltage.  Thinking of a 48v pack, its voltage when fully charged will be about 51.2  (that is four batteries at 12.8 volts), and when partly discharged could be around 48 volts so the converter needs to account for this. If the pack voltage is 50 volts, the equaliser would keep the tapped battery at one quarter of this, which is 12.5 volts.

When you run a big load, say an inverter, it can take whatever current it needs from the tapped battery, and then the equaliser can balance the string in its own good time.  In a way it doesn’t matter much if it takes a minute or an hour to balance the string again.

Even without a single large load such as an inverter, a few small loads all on at the same time can easily overload a regular dc converter.  You could easily have a load of 20 amps made up of smaller loads all on together.  Its needs a substantial dc-dc converter to can deliver this power.  By using an equaliser you can meet these transient peaks from the battery and then later the equaliser tops up the battery from this usage.

Sometimes a dedicated 12v battery is added, together with its own dc-dc converter to keep it topped up.  This is a similar solution but requires the installation of another battery.

Another advantage of an equaliser is that it works both ways.  So it allows you to have a mix of charging sources. For example you may have a grid connect charger operating at 48 volts to charge the main pack when your boat is attached to a jetty with power.  But when untethered you could use a 12v solar panel to charge the tapped battery and its charge would be distributed to the other batteries in the string by the equaliser.

This setup requires a common negative, that is the negative of the 12v is the same negative as the 48v.  And this can cause a possible galvanic corrosion problem if there are devices in contact with the water and bound by this common negative.  Most 12v devices on board will not be in contact with the water.  But if you use an anchor winch, it could create a return path by way of the chain and the common negative.  In this situation where an anchor winch is used, and the 48v side is used for electrical propulsion, it is recommended to switch the negative supply for both the anchor winch and the propulsion motor. (That is, its normally just the positive that’s switched, and the negative is usually connected to the frame of the device and remains connected even when the device is siwtched off. By switching the negative as well, the device is totally isolated from the rest of the wiring loom)  This keeps the 12v and 48v wiring looms from being connected through the water.  The remaining connection between them through a dc converter is ok.

And come to think of it, the idea of switching the negative of the anchor winch could be useful for any steel or alloy boat as well.

And closely related to this topic is charging from lower voltage solar panels to higher voltage batteries, or vice versa.  Both of these tasks can be easily handled and I’ll talk more about that in another post.

We have a few products available from Solar Converters, for various conversion. There’s equalisers, regular dc-dc converters, and solar chargers to allow charging from lower voltage panels to higher voltage systems.  If you need a converter for a particular task, let me know, I’m sure we can get one for you.

This . . . → Read More: New pricelist and stock]]> You’ll see that some of the product prices have been updated.  The most notable changes are for the Cruise models which we can now offer at more attractive prices. This is a result of Torqeedo Australia now being able to bring in a large shipment by sea which has reduced shipping cost significantly.

This sea shipment has now arrived and stock is available for pretty much all items.  Check the on-line store for availability of the various items.

The Solbian solar panels are proving popular and some of the sizes have sold out.  A new shipment is expected this week.  If you order from the on-line store, it will report stock status of the particular item when you add it to the cart.

This is a followup to the story about the solar powered zodiac trip Claude and I did from Pittwater to Sydney a while back…  I’ve now prepared a video of that trip for your enjoyment.

Its posted on youtube . . . → Read More: Video for solar zodiac trip to Sydney]]>

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

This is a followup to the story about the solar powered zodiac trip Claude and I did from Pittwater to Sydney a while back…  I’ve now prepared a video of that trip for your enjoyment.

Its posted on youtube and and available here on this page. The trip was an experiment to see how far we could go with a Torqeedo Travel 1003 assisted by solar power…

We used the old model battery which is 400Wh, compared with the new 520 Wh size. It had 17% remaining when we arrived at the destination.  Whats more interesting is how we were able to run solely on solar power for a large part of this adventure. Why not take a look—the video has many of the technical details but if thats not enough, go back to the previous blog entry, a link to this is shown above.

–chris

Come and see the Sienna solar boat at King George Square in Brisbane this Saturday 28th October as part of the National Electric Vehicle Festival. This festival is part of the National Electric Vehicle Convention and you can see more details of this at the website here. The . . . → Read More: Solar boat at electric vehicle festival]]>

On the Upper Noosa River

Come and see the Sienna solar boat at King George Square in Brisbane this Saturday 28th October as part of the National Electric Vehicle Festival. This festival is part of the National Electric Vehicle Convention and you can see more details of this at the website here. The builder’s of the Sienna, Scruffie Marine, will be on hand to answer any questions you have about the design and building of the boat or how you might have one built for you.

Unlike most electric vehicles this one is totally solar powered for its normal use. Its not built as an experimental vehicle, such as you see in the solar car race from Adelaide to Darwin, but built for everyday use to be powered by the sun. The solar power is not only use for propulsion but also for running the other electrics such as the fridge and lights as well as small fan for the composting toilet. It will be used in service as a rental boat at Pittwater and we are taking bookings now for December and January.

Using solar power alone, that is, not taking anything from the batteries, she can travel at around 3 knots. This is the perfect speed for quiet rivers such as the Noosa and the Caboolture. Using battery power she can travel all day at 4 to 5 knots.  From tests so far we expect the energy from one days solar power will be a close match for the energy required for a typical afternoon or morning outing on Pittwater.

Aggressor in Germany

Also on display with us will be the carbon composite planing eletric boat of Gold Rush boats from the Gold Coast. Max Buener, the designer and builder will be on hand to describe the details of this environmentally friendly speed boat. Noy only is it electric powered but its green credentials extend to its construction. The composite has a core of cork which is a renewable product and the epoxy resin used in its construction is sourced from renewable materials. This boat has been awarded the world’s most environmentally friendly boat because of its construction material and propulsion system.

Torqeedo Australia will also be at the festival with us and will be on hand to answer  questions you have about electric propulsion for boats.

We’ll also have information available about the Electric Boat Association and you can see more information about this group at the website.

The Caboolture River is a quiet picturesque river not far from Brisbane which offers a delightful cruise for a solar boat. The trip was partly for testing the boat but really just for the fun of exploring up river from Monties Marina on the Beachmere Road.

Tarci conning . . . → Read More: Solar boat trip on Caboolture River]]>

Its a dogs life...

The Caboolture River is a quiet picturesque river not far from Brisbane which offers a delightful cruise for a solar boat. The trip was partly for testing the boat but really just for the fun of exploring up river from Monties Marina on the Beachmere Road.

Tarci conning the solar boat

I had moved one bank of engine batteries from its original location to a position forward to help with adjusting the trim of the Sienna. This bank of batteries was not installed yet, just located in place so we could the effect on trim, which is good. I’ll now be able to go ahead with making a shelf for them and to complete the power connections and cell monitoring. The new location has limited height available so they will be laid on their sides facing the centreline of the boat. The location will be awkward but, hey, boats are like that.

Here be dragons

So for this trip we were using the remaining two banks of engine batteries to power the Cruise 2. Sometimes we travelled at full speed which was around 6 knots with some assistance from the tide which was still slowly filling and almost at the top. And for some of the trip we travelled at around 3knots using only the power from the sun. At this speed on a sunny day the motor is using just solar power alone and not taking anything from the batteries. We started this trip about 12 noon and by the same time the next day the batteries are full again. We were boating for about three hours and in that time used only the power we can get from the sun in one day.

View from the bow

The Caboolture River is flowing in its floodplain and takes a very windy and interesting course. The banks are sometimes open cow paddocks and sometimes lovely dappled grassy glades in the forest. The kind of places elves would love to hang out.

Dining table of cedar and hoop pine

The Sienna is remarkably efficient and is proving to have a nice match of solar power and motor size. We motored at whatever speed caught our fancy and its cool that this matched just about exactly how much power you can get from the sun in one day.

There’s space on the roof for more panels but if today proves to be a good example, there will be plenty enough to provide the power thats needed for boat rental.

As well as powering the engine the solar panels also run the fridge, which we put to good use today, and it also runs a small fan in the composting toilet. The composting toilet is a great solution for any boat.

Elven glades beyond the fringing Mangroves...

I’ll be putting one on Current Sunshine when I have some spare cash.  It does not require a holding tank and therefore doesn’t require holes in the hull.  As well it doesn’t smell and you end up with nice garden compost.  And easy to dispose of.  On Current Sunshine the holding tank is about as good as you’d get and still it is troublesome.  It needs to be emptied regularly and in contrast to a composting toilet, gets worse the longer you leave it.

The small fan that draws fresh air into the toilet directs to a tube which is meant to lead through the roof to the outside air.  But I haven’t had a chance to do this yet and so its just exhausting into the toilet compartment.  And yet even with this poor arrangement there is still no unpleasant smell.  There’s a slight damp kinda musty smell, not unpleasant, that you get in cellars and caves.  But overall I’d recommend a composting toilet if you’re vaccilating over it.

I’ll write more about this soon, but to be going on with, here is a link to a video of the launching of Stillness

And here’s a video of her crossing Lake Cootharaba into a stiff breeze. The rattling you hear in the background is the flapping . . . → Read More: Solar boat launching]]>

Stillness on the Noosa River

I’ll write more about this soon, but to be going on with, here is a link to a video of the launching of Stillness

And here’s a video of her crossing Lake Cootharaba into a stiff breeze. The rattling you hear in the background is the flapping of the straps for the drop down clears.

Today I towed the Sienna out of the shed and into the sun to test the solar panels and the charging of the lithium batteries.  This is the first time the batteries have been charged as a group and they need to be watched carefully for . . . → Read More: Sienna in the sun]]>

Sienna charging the batteries in the sun

Today I towed the Sienna out of the shed and into the sun to test the solar panels and the charging of the lithium batteries.  This is the first time the batteries have been charged as a group and they need to be watched carefully for the first few cycles until they become balanced.

After being in the workshop they have become covered with fine sawdust—after all it is a working boatbuilding shed and Derek has been working on other projects. And have a look at this lovely little sailing tender that Derek has been building.

Selkie sailing tender

It would be fun to sail this little boat huh.  But back to the chase…

When I first took her out in the sun she was harvesting 8.4 amps from the sun. After the brushing the dust off, that increased by about  1 amp, and after washing them, another 1 amp.  But the sun was dropping in the sky quite quickly by then and the lower angle to the solar panels was reducing the output by about the same amount so after they were cleaned they were still doing a little over 8 amps.  This is about 200 watts. Under ideal conditions they should produce 560 watts.

Sienna lithium cells with cell protectors and main battery cables mostly complete

There’s 52 lithium cells in this boat and they will be at slightly different charge levels and so the first few charge cycles will be used to balance the cells. The highest charged cells will become fully charged first and their cell protectors will begin bypassing current, to bleed off a little power. The charging needs to be stopped soon after the first cells begin bypassing. Today none of the cells started bypassing. I’m not surprised because they had barely two hours charging before the sun dropped behind some trees.

I will cycle the cells a few times over the next week using solar charging and also mains charging, which will be easier than towing her out into the sun each day.

Daisy-chained cell protectors being installed

Today the battery management unit was not connected yet so to monitor the cells I used  multimeter to test continuity of the cell protector signal line.  There is a single wire that daisy-chains all the cell protectors together. This circuit on this wire is monitored for continuity and if this breaks we know that a cell has gone over-voltage. I have partly wired the battery management today and tomorrow it will be part of the system and so if any cell goes high the charging current will be cut automatically.

Deb helping out with the water testing of battery boxes

I want the battery boxes to be totally waterproof and during the building we filled each box with water to prove that it was indeed waterproof. The first two that I did leaked a little and this gave me the chance to fix them. The last two—see the picture of water testing—were ok. With a perspex top screwed down they’ll be totally fine if somehow the bilge gets full of water.  And being perpex a simple glance will show the green LEDs of the cell protectors to show all is well (or not if there’s any red ones).

As well as the engine batteries there are 4 house batteries (to make 12 volts) and these will be charged using a dc-dc converter.

Sienna at night in the shed under her own lighting

Much of the work is now complete for the house wiring and you can see how nice the lights look at night. Even though this photo was in the shed you can still get a sense of the delightful woodwork in her.

We’ll be showing her at Noosa next Sunday at the yacht club and I’m hoping that all the electrical work will be complete by then.  This occasion will be the Scruffie Marine launch of the Sienna design and we plan to be able to offer short trips on her up the clean Noosa River. The Noosa river is the only river in a well populated area that is still largely in its natural state.  So its appropriate for the first showing of this environmentally sensitive boat to be the relatively pristine Noosa River.

I snuck way from the solar boat project under cover of darkness to check out Claude’s radical trimaran—kind of reminds me of a stealth bomber especially in its current grey livery. The weather around these parts has been pretty rainy and windy as you can see from the . . . → Read More: Cruise 4 Stealth Trimaran first tests]]>

Sneaking up on a pelican—not

I snuck way from the solar boat project under cover of darkness to check out Claude’s radical trimaran—kind of reminds me of a stealth bomber especially in its current grey livery. The weather around these parts has been pretty rainy and windy as you can see from the photos.

Even though its not ideal for getting a reliable speed vs power consumption readings, it good to be able to get a sense of the boat’s performance against the wind. The photos here are from two days earlier.

Claude at the wheel—cutting cleaning through the water

Claude is the owner of T0rqeedo Australia, and has a tendancy to try interesting things, as you might have seen in our recent trip from Pittwater to Sydney. (And just google Claude Desjardins and you probably find something about his journeys around the Pacific.  Years ago he sailed the Pacific from Canada in an 18ft trailer sailor designed by Bruce Roberts.)  But back to the chase….

Claude wanted to have a small boat that could be easily driven so that it might be a good match for electric power.  So he commissioned Tony Grainger to design such a boat, without expectation of how a boat should look. As you can see, all bets are off when Tony gets a challenge.

Drag inducing turbulence is visible around the motor shafts

Keep in mind that this is its first river trial and there’s been no opportunity to fine tune critical speed aspects such as the paint job…  er,  I mean, the motor positions, and depth of the hulls etc.

The motor positions are critical for speed and efficiency and this has not been optimised in any way and we expect both speed and efficiency can improve radically with better positioning.   There’ll be other changes as well, and I’ll keep you posted on her development as she gets updated.

In this trial she’s set up with eight Optima batteries and 2 Cruise 4′s. On the day I was on board, it was very similar conditions to what you see in the photos. Below are the results from the data I recorded that day.

Despite its looks, its quite stable, and handled the gusty conditions on the day with aplomb. It knifes through the water and cuts through the wake of other boats with ease.  The motors on the day were fitted with standard props and so they topped out at a maximum power of below 7000 watts—so there is still more power available.  The motors had reached full revs, and so it needs faster props to get the best speed for this hull.  As well, there’s a lot of wash around the motor shafts and better positioning will reduce the drag.

You can see the video on youtube