Twin alternator wiring diagram

I'm tiring to explain a twin alternator charging system to my mate (unsuccessfully) can anyone point me in the direction of an idiot proof wiring diagram as my attempt looks like an explosion in a noodle factory!!!

Twin alternator? Why do you need 2 alternators? Sorry if its a silly question I'm just curious

Is this to two batteries? If it's to one then I really wouldn't bother but would just fit a larger alternator. If it IS to two batteries then the heavy B+ wire goes to +, the casing goes to vehicle earth, the exciter wire needs to emulate the equivalent on the main battery system so you need a bulb, a diode and a resistor. Just follow the same diagram from the main wiring diagram

The resistor is optional BUT without it the system will stop charging if the bulb blows.
The alternator may well include the diode.

It is for a twin alternator twin battery set up. To satisfy your curiosity I'm also running either a heavy winch or a pump but not both at the same time. I can happily wire it in myself. I was just trying to explain how it's done to a mate of mine.

I've just done a diagram on Eagle for you...

Note:

The relay, 2 x fuses and switch are optional but with the switch in the ON position it will lock both batteries together as one when the ignition is on.

With the switch on - This allows either alternator to charge both batteries.
With the switch off - This disconnects both batteries which are now independent

With the ignition OFF the 2nd battery will always be disconnected from battery 1 so that you can draw power from it whilst always being able to start the car from the first battery.

Blue wiring = existing wiring
Green wiring = new wiring

R2 is also optional BUT without it the alternator will stop charging if the bulb blows.

The fuses (in either version) should be 50-60amp fuses.





Here is the alternative SINGLE alternator DUAL battery version (split charge).

Note that the switch now allows the 2nd battery to be charged so it's default position is ON. When the ignition is off the batteries are disconnected from each other and you can draw power from it without flattening the main battery. The idea is that you connect your lights, stereo, CB, cigarette lighter etc to the 2nd battery.