rallysman;1669106; said:How about using a battery isolator that will allow the secondary battery to charge while the car is running, but separates it from the cars system while it's off? I've used continuous duty golf cart solenoids for this when I was doing car audio and it worked well.
With that method, you could just hook it up to the secondary battery and not have to mess with it (unless the car will be of for quite a while).
they make a solid state device like this for marine use as well


