Battery bank guidance

walleye

So I took my house batteries into the auto parts store today to get them tested.  They said they were OK but were being over-charged. To recap, the PO had group 27 starters for the house bank and they were rated CCA 840 and tested at around 860. On my voltmeter, they were testing at 12.5 which I found odd (would have thought they were higher if supposedly getting overcharged?). Anyway, I'm stumped and not sure what the issue could be.  Thoughts or suggestions?

MarkB

Don't know too much about the specifics, but on my charger I can specify the type of batter it is charging for each of 3 independent battery banks. I believe I can choose from deep cycle, crank and gel.  Not sure if the wrong setting could overcharge the battery. I suppose so, if the option exists to specify battery type.

Cableguy Greg

walleye said:

So I took my house batteries into the auto parts store today to get them tested.  They said they were OK but were being over-charged. To recap, the PO had group 27 starters for the house bank and they were rated CCA 840 and tested at around 860. On my voltmeter, they were testing at 12.5 which I found odd (would have thought they were higher if supposedly getting overcharged?). Anyway, I'm stumped and not sure what the issue could be.  Thoughts or suggestions?

If you have starting batteries on the house circuit like you are stating, they drain very fast. They are designed to start the engine and that's about it. If you are on the hook for a long time, playing tunes, running the fridge (or two), you will drain them very fast and be left with no tunes and no fridge. Deep cycles are the way to go for the house batteries. If the two 24's are in good shape, then I would replace the two 27's with deep cycles, group 31's if you can fit them in there.

majorboats

Just purchase 29-31 Duracell at Sams for 93$, great deal !

majorboats

On my 300 the Star Port batteries are for the Star Port engine and Gen, Port side is for Port engine and house.

Michael T

For anyone replacing house batteries you may want to look at the new thin plate pure lead AGM batteries. The series 31 typically have 105+ Ah, 220+ reserve minutes and more than 1300 MCA. Best of all they have absolute best battery chemistry available for charging acceptance rates as they charge in excess of 300% of their Ah which is huge - because this means they charge up super fast - in fact more than 15X times faster than gels and crazy faster than flooded. Even better most of them can be discharged to at least 80%  about 450 times. BTW no matter which type of battery you use in your house banks - if you don't wire them as Frenship showed earlier in this thread (and many boaters haven't) you may as well use them for anchors.