Thread: alternator charge wire, where does it go.

Originally Posted by leyland

hi all i have a 1983 3.5 v8, lt95 gearbox with the twin carbies, all appears to be original under the bonnet, at the moment i have 2 batteries connected by one of those manual boat isolating switches, with positions, battery 1, battery 2, both batteries, and off, i want to put a soleniod isolator in so i dont have to manual switch for using accessories. my problem is that i dont know where the charge wire is to charge the batteries. the wire coming out of the back of the alternator dissapears into the firewall. where and which wire would i use to connect to the solenoid isolator to charge the batteries, on other vehicles i have there is a wire going directly from the alternator to the battery (with internal voltage regulator) or from alternator to voltage regulator then to battery. thanks form peter.

Not quite sure just what you are asking here, especially about the charge wire disappearing into the firewall. Maybe it is going to an ammeter in the cab. The usual place of connection for the "charge" wire is at the starter solenoid. It will be a smaller wire connected to the same solenoid terminal as the heavy cable coming from the battery, even if it goes into the cab first. Can`t help with your isolator, but those type of aftermarket accessories usually come with a connection diagram.

When I did the dual battery on my D1 3.5i, I used the wire that feeds the charging light on the dashboard. This wire starts off as an earth and then, when the alternator is running, goes positive. Thats how the charging light goes out. I just took a feed off this wire to a solenoid and then one from earth to the solenoid. Consequently when the wire from the alternator went positive it engaged the solenoid which in turn linked the two batteries.

HTH

Ivan