Also.. what's the point of putting in the relay? Why not just throw another battery in parallel, wired exactly the same way as you described, but without the relay? That way both batteries would also work when the car's off, and not just when it's on, right?Originally posted by scooby_93
I'll try and explain how I've got the two batteries rigged up. Here goes:
First, I have a relay situated near the battery under the hood. From the relay, I have a 60amp fused live wire going into the positive terminal of the battery under the hood. On the other relay terminal, there is another live wire going from here to the positive terminal of the second (auxilliary) battery, which is situated in the back of the car. This wire also requires to have a 60amp fuse near the aux battery. Again, from the positive terminal of the aux battery I have another live feed from it going into a 1.5 Farad Capacitor, which then comes out and continues onto a one-in-two-out fused distribution block and then goes into the positive on the amp.
Going back to the aux battery, the negative terminal just goes to chassis earth. The negative terminal of the Capacitor also goes to chassis earth, as does the negative on the amp.
Going back to the relay (remember there are four pins on the relay), you have an negative which can go to chassis earth or the negative terminal on the first/main battery and then there is also a switched ignition feed required.
I know this sounds really complicated, but honestly it's not. If you want, I can send you a diagram which will be a hell of a lot easier to understand.
The way this is wired, as soon as you start the car up, both batteries will charge.