Onboard Charger

I have an onboard charger that is in a boat that I bought last fall. It is a promariner 3 bank charger. I have owned big boats and small boat for the last 50 year but have never used one. Can I hook this up to my started battery as well as my trolling motor battery? Can I leave this plugged in 24-7 all the time or should it only be left on for a short while and will it go down to trickle charge as needed when it is left plugged in. Thanks for any help. I looked for a manual online but could not find one and this I am guessing is an older charger. At this point I have not checked it out to see if it even works, but it looks in good shape

I have one on every battery and wouldn’t go any other way… as many do here. Mine is plugged in all the time. A good charger will power down to a trickle when more power isn’t needed. Personally, I’d assume it has that same capability as that was the idea of what the chargers were desired to do from even early on.

If in doubt, does it have a model number any where on it? Post it, someone will find more info.. they always do.

Typically, you can connect standard lead acid and AGM batteries all on the same charger (including starting and deep cycle). Gel batteries might need to be connected to a different charger unless new technology can distinguish the difference. Some chargers have a setting if charging gel vs acid/AGM.

If standard lead acid, I would keep it connected and plugged in all the time. If AGM, I’d disconnect after the batteries are charged up…AGM batteries can hold a full charge for a really long time. My AGM batteries are topped off come fall and still fully charged when spring hits after sitting in the basement. I so no purpose of keeping them plugged in.

Thanks for the input. I now feel better about leaving it plugged in

I would make sure to unplug it when a thunder storm rolls thru. A lighting strike near by could fry the charger.