My TJ came with the painless dual battery installed. I've had for a year and no problems. One day jeep died, so I flipped switch to dual battery start, no problem works, jump myself. switch off or to aux charge and jeep dies. First thought: dead main battery, clean batteries, charge batteries, switch batteries even changed the connectors on main as looked crumby. Still same problem. not alternator as it;s charging battery. thought must be the painless solenoid not working right, as all wires and fuses good, alternator working. Just won't run unless batteries are parallel!!
So i researched and bought a PAC 200 relay/isolator/solenoid ($46) to replace painless as it looked worn out. installed it hooked up wires, checked fuses again; AND SAME THING!!!! jeep only has power when batteries/ switch in parallel!!!!!
Help, if you got it, please! don't tell me i don't need the dual battery system lol, as it's already hooked up and runs trailer, and aux 12 volt port (self jump with switch great too.)
Both batteries red top optimas, and fully operational, just don't want to run batteries parrallel all the time, cause then what's the point??