I am not happy with my
Wrangler Dual battery system from Dirty parts (see thread). I am not an expert but I am losing battery power on BOTH batteries when one goes out. I have it set on A. There is also a BOTH setting and a B. But setting B does not restart my dead battery. I guess it's switching over? see my post for more info:
Dual Battery System not working
Once charged up, the B battery does start the car.
It could be my error, maybe I don't understand the system. But I though i was supposed to be a able to switch to B and "jumpstart" my car. In any case, that's what I had to do with cables. I'd be better off just carrying a cheap motorcycle battery in my car...
