My daily driver is a 78 crewcab and im hooking up dual batterys. As i have it right now i have both wired positive to positive and then both grounded to the block. Works fine, but i want to have the second battery isolated so i can never be left with a dead battery.

been doing tons of reading and i know i can buy a battery isolator but ive also seen people wiring up a second solenoid and a switch in the cab.





Now if i wire a solenoid and a switch, will the aux battery stay charged? Lets say i leave the radio on or key on and main battery dies and wont crank. flip the switch in the dash and im cranking off the aux battery? will this setup leave the aux battery always charged so i will never be stranded?

I have a stereo in the truck and a winch on it and i have been left with a dead battery before and i just never want to be left out with a dead battery.