Possibly odd battery config (3396)

M

mhanch

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Oct 9, 2007
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28764
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I went down into the engine space to do some maintanance and cleanup, and noticed that my boat uses 4, six-volt, wired into 2 12-volt banks. these are used both for starting and house. Is this normal? They are all deep cycle, and everything starts fine. (both engines)

The battery switches in the panel have a Starboard and Port switch, so I can support 4 batteries if desired

Would it make sense to replace them with 4 dual purpose 12 volt batteries when their time is up? or is this a good configuration?
 
You might do better asking this on the "Engine-Electrical" forum. It's not really a Carver issue.
But, to answer your question depends on how much amperage this setup has. It may have more than 4 standard 12 volt batteries.

I hope this is a new boat and you just trying to learn the ins and outs of your boat.
 
somebody probably wanted more battery capacity. nothing wrong with it. You need to determine what load amp hours both start and house before deciding on the next set. If it is a gas engine boat most group 27 batts will start it fine though you wont have much house capacity. the trojan battery web site has a lot of size and amp hour data in the technical section.
 
Yup, this is a typical configuration to obtain more capacity. However, to save money, it is more typical to see it done only for the house battery, not for both.

If you replace this setup with 4 12V batteries, you'll need a charging system to recharge all of them. Most chargers handle 1, 2, or 3 batteries. You might end up having to buy another charger, or install a combiner, etc.

By the way, as far as the charger is concerned, two 6V batteries in series appears like a single 12V battery to the charger, so you can get by with a 2 bank charger in this setup.
 
i've got a similar setup with 4 6v batteries. however, my 4 batteries are only for my house system and they're trojan t150's to provide long amp hours. each engine has it's own marine starting battery. i've been told that's the "correct" way to do it, but i'm not sure as the boat came that way.
 
I would be shocked if this boat came that way from the factory. This is likely an aftermarket job, FWIW...
 
it's a 1977 Mariner, so the factory config disappeared sometime in the early 80's i'm sure. I just need to figure out what to do when these batteries need replacing.
 
a pair of golf cart batteries in series will give you about 220AH. chances are that was replacing a single battery of half the capacity.

if they can crank the engines just fine, then stick with that and enjoy more time anchored... the only down side to golf cart batteries is that they are not designed for starting which is a high amp load for a short time. If your engines start quickly and you dont' have crank and crank and crank... they're great.

I have golf cart batteries on my boat, both for house and cranking and they crank the big Detroits just fine. although there are 4 x 8v for 32v so the higher voltage means less amps and heat.
 
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