2 Batteries wired Parallel - equivalent to 1 bank?

[flaudia402]

* Since I didn't get a single response in the Maintenance/Tech. Section I'm posting here since it seems you guys are more helpful here*

Mods feel free to close the other thread.

I've got four batteries total in my 2006 SAN 220. Two are running my stereo equipment and the other two are my starting. Each pair is wired parallel. Do I need a 2 bank charger/maintainer or a 4 bank charger/maintainer?

Thanks!

[74green]

Don’t have an exact answer to your question, but considering one pair of paralleled batteries I would think = 1 bank. While your engine is running your alternator is currently supplying a charge to both batteries since they are paralleled. So I don’t see a difference as to why you can’t use a 1 bank charger to only one battery since both already get charged simultaneously anyways. Otherwise you would have to isolate them I think if you were going to charge independently with a two bank charger…

That’s just my thought. May somone with more background then me will also chime in if im mistaken...

[flaudia402]

Thats what I was under the impression of as well. Since two batteries are wired as one - the voltage is remaining the same, thus one bank would sufficiently charge both batteries.

Any other opinions?

[74green]

Right. With your case (having 2 pairs of paralleled batteries) I think you would either use:
A. 2 bank charger
B. 4 bank + isolate the batteries with a Perko switch or equiv.
Although if you went the 4 bank+switches route it might be faster charging time , but = $$

Maybe contact David from Earmark Marine if he doesn’t chime in. He would probably have a yes/ no answer for you. He was very helpful with my questions about VSRs.

[RyanATX]

Why would you need two batteries for starting? Isolate a single battery for starting, use 3 for stereo.. get increase stereo party time.

[EarmarkMarine]

flaudia402,

For your scenario you would use a dual bank charger. Even with a 4-bank charger there is no convenient way (without a bank of switches) to isolate the batteries so that four banks could operate in isolation.

Are the two stereo batteries identical in age, size and chemistry? What about the starting batteries?

David
Earmark Marine

[flaudia402]

My 220 came with a pair of stock OEM batteries. I pulled the battery out that my stereo was originally hooked up to and put in a pair of Sears Diehard Marine batteries. Since I had the stock OEM battery out of the boat I figured I'd wire it up to the starting battery since it is exactly the same. I didn't think that wiring three batteries (2 identical and 1 different) would be a good idea. Though, they are the same size - perhaps slightly different in amperage and cranking power.

[EarmarkMarine]

flaudia402,

Yes, you're right.
The three paralleled batteries would need to be equal.

Also, while the extra reserve capacity would be a plus, I'd be concerned with bringing three depleted batteries on-line suddenly with your alternator. A stock alternator is not intended for that type of load in combination with the stereo draw and boat operations.

Your AC charger should have a capacity of 10 to 15 percent of your batteries' total amp/hour rating. Shoot me an email for some options.

David
Earmark Marine

[flaudia402]

So then keeping the batteries on an onboard battery charger/maintainer is not a justifiable option?

[EarmarkMarine]

flaudia402,

I think we're on the same page. My thoughts coincide with your stated objectives so you lost me on your last question.

David
Earmark Marine

[flaudia402]

David,
Sent you an e-mail - thoughts about this onboard charger?

http://www.boatersworld.com/product/MP63528907.htm

Thanks!

[EarmarkMarine]

flaudia402,

I received your PM and I definitely sent a response. Sorry, not sure why you didn't get it.

You might try sending an email so we can communicate outside of the forum.

In any case, I'll try sending my response again.

David