There is now another way to split the charging of your batteries. Instead of using relays, its now possible to use a split charge diode block. The first units produced  did  use actual diodes, whilst the units worked, they were not efficient due to the voltage drop of around 0.8 - 1.2volts, this doesn\'t sound a lot, but in terms of charging batteries it is  quite a drop. To overcome this voltage drop, the modern units as supplied by Sterling use clever circuitry with mosfets, the result is that the voltage drop is now lowered to around 0.04volts Any problems associated with the above relays and provide a good positive supply to both battery banks, whilst maintaining total isolation between them. The split charge diode blocks are incredibly easy to install, as shown in the following drawing. The best way way to install this unit, and to avoid any changes to the vehicles wiring, is to disconnect the main feed cable off the back of the alternator, thoroughly insulate it and tie it out of harms way with something like cable ties. You can now run a fresh cable from the alternator to the diode block, and two more to the two batteries. Basically that\'s it. By using the above method, its very easy to remove the diode block and make good the original wiring.