Onboard charger for 12v parallel batteries

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09-30-2012, 11:38 AM
drifterdon

Onboard charger for 12v parallel batteries

I have a question or two about hooking up an onboard charger.
I am about to get my new boat which will come with 2 batteries, 1 for starting and console, and 1 installed with the 12v trolling motor.
In this scenario I see where a 2 bank charger would be just fine.
If I were to add a third battery in parallel with the trolling motor battery, would the 2 bank charger still be sufficient, or would I need other items also to isolate them from each other while being charged?
I did a search but can't find anything on this specific scenario. Thanks for any help.
09-30-2012, 11:53 AM
Barnacle Bill

A 2 bank charger would work but just take longer to recharge 2 batteries and this would also depend on the output of the charger. They do not need to be isolated but should be identical batteries. If it were me I would install a 3 bank charger. This would shorten recharge time plus if you ever decided to go with a 24 volt system all you would have to do is wire the batteries in series and you are good to go.
09-30-2012, 12:00 PM
drifterdon

Thanks Bill,
So it would not hurt to have a charging lead to each battery even when the two are hooked in parallel?
09-30-2012, 05:54 PM
CatFan

Quote:

Originally Posted by drifterdon

Thanks Bill,
So it would not hurt to have a charging lead to each battery even when the two are hooked in parallel?

No, it would be fine that way.
09-30-2012, 09:48 PM
drifterdon

Thanks guys, I appreciate the input.
10-02-2012, 04:56 PM
new slab hunter

i have a 3 bank charger, one for start, and have a two batteries hooked parallel, and one of my batteries is getting real hot and i have to add water like crazy,,,any thoughts?
10-02-2012, 07:26 PM
CatFan

Quote:

Originally Posted by new slab hunter

i have a 3 bank charger, one for start, and have a two batteries hooked parallel, and one of my batteries is getting real hot and i have to add water like crazy,,,any thoughts?

That battery is most likely bad. Remove the parallel connection and see what happens when you charge.
10-02-2012, 08:51 PM
Cray

Don, I have the setup you are talking about and it works ok just takes longer to charge as Bill said. If I was starting out from scratch I woul go wit the 3 bank though.