charging question converter/charger

[BentWheel]

My new to me boat has a converter / charger I have no experience with this type of device and don’t have a manual so I hope someone will share their knowledge with me.

The converter turns on at the breaker box and has 2 red and 1 black wire that runs to my perko switch. When I turned on the converter ( it’s a 30 amp ) the dial went to about 18 or 20 amps. I have 2 batteries installed in the boat but had the perko switch turned to the off position.. the next day battery 1 was pretty warm to the touch but battery 2 was not….. and the boat didn’t have enough juice to start. I connected a battery tester to the batteries and according to the tester they both needed a charge.

So how does the perko switch work in this scenario? Should I keep it in the #1 position or both (1 and 2) position when charging… or is it designed so that it will still charge a battery even if it is in the off position? One buddy thinks I have a bad perko switch I think that the perko switch isolates the 12v system but still allows the battery to be charged.. if I am right then I either have a bad charger or bad batteries.. or maybe I was wrong to put the perko switch in the “off” position.. if so i cant explain why battery #1 was warm to the touch

i appreciate any feedback
thank you
Dwain

[tallyhorob]

You need to start chasing wires. People have lots of ideas about charging and you never know what you have until you sort it all out. Some send the charge voltage to the switch so you can charge one or two or both. But if you flip it to off it could pop the diodes, so then someone may run a wire to a battery to give the alt. current some place to go because they are want to prevent that. Its all a guess until you see what the people before you did.