Sorry, Jar = Battery case containing cells. We call that a Jar but it's a slang term. So I have 4 batteries in all, two for each string and each string of two is wired in parallelly. So the voltage is equal to the value of either battery, 12V, with the AH equaling the sum of the two batteries.
Yes, the switch is OFF / BATT #1 / ALL / BATT #2
The information on line, for teh ProSport seems to indicate that each battery (Jar) is connected individually in a string rather than connecting the full string. This just seems odd and different than any other charger I've connected to UPS or Generator.
Ok. So as I understand it, you currently have four batteries, arranged into two banks of two batteries each wired in parallel, connected to a factory 1-2-Both-Off switch as bank 1 and bank 2. That correct?
If so, you should do a bit deeper dive into why your setup is arranged like that. Because there’s probably no reason to be lugging around that many batteries.
First things first: you need to separate your house and starting circuits. They require different batteries for different purposes. It’s possible that at some point, it was determined that the boat needed “more battery power” and so both banks 1 and 2 (as arranged from the factory) were upgraded with an additional battery to provide that capacity in both switch positions. If your circuits are properly separated, that’s not necessary. Here’s how:
Your engine most likely requires a GP24, at most a GP27 cranking battery per the manufacturer’s CCA requirements. Check your engine manual if you’re not sure. Certainly no reason to need paralleled 12v batteries there. One battery will do just fine.
Unless your house electrical loads are unusually high for the way you use your boat, a good deep cycle GP31 should give you all the power you need for your lights, pumps, electronics, etc. That may require a bit of load calculation; it’s possible that you may need a paralleled bank for the house power if your load is for some reason extremely large (big stereo amp, inverter, electric reels, etc.). Regardless, at the most you might need two batteries in parallel (or one big one) for just this bank; but it’s likely that one reasonably sized battery will suffice.
Rearranging those circuits gets you into the realm of needing either a two-bank or three-bank charger. With the BEP switch, most of your battery charging will be taken care of by the engine alternator; the charger mostly functions to top the batteries off that last little bit that the alternator won’t do effectively and to serve as a trickle charger/maintainer during longer periods between use. Therefore, a 8-12A charger is likely all you need.
As said above, either way, your TM battery bank of one lithium or three lead acid batteries will needs its own dedicated charger. Each LA battery should be charged individually; it keeps each one at a better state of charge and the charger’s internal computer will monitor the batteries individually for any faults. There’s no shortage of three bank chargers on the market for this application. I’d suggest the 20A three-bank ProMariner model for quicker charging time if you decide to go that route.
