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. Sterling has developed a range of low cost split charge diodes. These diodes have enhanced performance over conventional diodes and at a lower cost. The difference is in the devices. All other split charge diode manufacturers use conventional alternator diodes, which at low current flow have about a 0.93 voltage drop. When the full rated current of these diodes is approached, the voltage drop increases to about 0.95 volts. This results in excessive heat and power loss across the diode. For example: A conventional one alternator in and two battery bank out, tested against a Sterling unit had the following results: Technical information   Conventional Splitters Sterling Splitter Amps passed 30A 50A 60A 70A 30A 50A 60A 70A voltage drop 0.93 0.95 0.97 1.1 0.78 0.75 0.74 0.74 Power loss (w) 27.9 47.5 58.2 77 23.4 37.5 44.4 51.8 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.