can i charge 2 batteries parallel w/ 1 float charger?

[jroden]

I was going to add a second battery to my camper. I have a second float charger so I can disconnect them at home and charge them separately (my RV converter is shot) but was wondering it I could leave them wired together and just hook the charger to one battery. Sorry if this has been asked a million times, my charger is nothing sophisticated, just a "battery tender"

[ddndoug]

pianotuna wrote:


This is what is balanced and best for twin twelve volt batteries.




Others may say it doesn't matter--but unless there is a compelling reason to not optimize charging and discharging why not do it the best possible way?

X 2

[wa8yxm]

Tempting to pick nits here and say no.. However the answer is YES.

WHy the no.. Well when you hook up more than one battery in parallel the "Become One" with each other and thus you end up with ONE big battery.
Same as when you put two sixes in series.

The suggestion of charging them independently THE FIRST TIME, is a good one though

But it will work just fine.

One side note.. There is a limit to the SIZE of the battery your maintenance charger can maintain... Usually you need about 1% of the 20 hour amp hour rating for the maintenance unit.. IE: 100 amp hours, 1 amp.

But there is a lot of flexibility in that ratio.

[handye9]

jroden wrote:
is there a handy way I can attach the two to the shelf on my tongue, will they fit in a big toolbox with some vent holes or something like that?

Depends on size and location of the shelf, tongue jack, and propane bottles, plus the size of batteries. Group 24's are a little smaller than 27's or 31's. Side by side 24's may fit when, side by side 31's won't.

Maybe, modify the shelf to accept batteries in a north / south position vs east / west position.

On my current TT, batteries fit side by side (group 24 e/w position). Last TT, I modified the shelf for N/S positioning. I also, had a TT with one in front and one in back of propane bottles. In all configurations, I used individual battery boxes.

[jroden]

is there a handy way I can attach the two to the shelf on my tongue, will they fit in a big toolbox with some vent holes or something like that?

[pianotuna]

Hi,

You can charge them together.


This is what is balanced and best for twin twelve volt batteries.



As it often doesn't cost a dime more to do this, I think it is worth the trouble.

If you wish to understand the "why" surf here:

correctly interconnecting multiple twelve volt batteries

Others may say it doesn't matter--but unless there is a compelling reason to not optimize charging and discharging why not do it the best possible way?

[beemerphile1]

You use them together and can charge them together.

[Norskeman]

You should be able to charge both batteries - the charger should go on "current limit" if they are near discharged. When you tow they should be charged from the tow vehicle.

I always have 2 batteries in the RV. I purchased a battery box designed for 2 6V batteries to contain them. Modified it to use the vent rig from the original battery. No problems charging the batteries.

Only need 2 batteries when I dry camp - twice a year at Watkins Glen race track.

Before I install the batteries in the spring I pre-charge them with a battery charger.

I have a 30 amp RV plug mounted in the outside of our garage and leave the RV plugged in - close the breaker feeding the RV plug to charge the batteries once a week when not using the RV.

[jroden]

Mandalay Parr wrote:
I would charge them separately first then hook them together with your charger.
Will get them off to a better start.

OK, I can do that pretty easily. I don't camp a lot so it's easy to just remove them.

[Mandalay_Parr]

I would charge them separately first then hook them together with your charger.
Will get them off to a better start.