Battery Equaliser 48 to 12v

This is a specialised dc converter that allows you to tap a 12v battery in a 48v string, and to keep its charge balanced with the whole string. It works by keeping the 12v battery always at one quarter of the voltage of the full pack.  This allows 12 volt devices to be attached to one of the batteries in a string of four, and it state of charge is always equalised to the other batteries in the bank. You can have transient loads that are higher than the maximum current of this device.  For example you could have a load of 20 amps running for a few minutes which would draw down the voltage of the tapped battery.  The equaliser can balance at up to 10 amps, so it might takes 10 minutes to equalise the charge again.  For typical usage it doesn't matter that it takes a while longer to equalise the charge.

This device has the added advantage that it can equalise in both directions.  So you could use a 12v solar panel to charge the tapped battery and the equaliser would distribute this charge to the other batteries in the string.

The maximum current on the 48v side is 2.5 amps.  This equates to about 10 amps on the 12v side.