Battery Question

[ybconway]

If I have room to add another house battery can I just use the existing charging system. Do I have to match the capacity of the two existing house batteries.

[theoldwizard1]

ybconway wrote:
If I have room to add another house battery can I just use the existing charging system. Do I have to match the capacity of the two existing house batteries.

The biggest problem with "adding" a battery is that the old one will "pull down" the new one down and it will have a shorter than average life.

[memtb]

ybconway wrote:
If I have room to add another house battery can I just use the existing charging system. Do I have to match the capacity of the two existing house batteries.

You should match the size and the age for optimum performance. So, unless yours are quite new....you’re starting from scratch. We just did exactly that, going from two to four. We waited until our old 2 batteries passed away! memtb

[ron_dittmer]

If you currently have one 12V battery, and you have room for two side-by-side, consider two-6V golf cart batteries. They are a couple inches taller so keep that in-mind. Two true deep cycle 6V golf cart batteries will charge and discharge very evenly for much better performance than two 12V batteries.

Just about every on-board built-in RV battery charger can charge two batteries. A pair of 12V hooked up in parallel, or a pair of 6V batteries hooked up in series, it makes no difference to the charger.

A number of motor home manufactures have been installing a pair of 6V golf cart batteries for greatly improved battery performance and reserve power, so it's not a crazy idea.....and there is very little difference in the purchase price. We bought our 6V golf cart batteries from Sam's Club. We bought 6V AGM versions in 2015 and they are still performing wonderfully.

I would rather have two 6V conventional wet acid batteries than three 12V batteries. The 12Vs discharge and charge unevenly making for inefficiency and battery boil-overs.

[BFL13]

Assuming you just need more AH in the bank than you have now, and that you have a pair of 12s at say 85AH each for 170AH, and that your third would make that up to 255AH, then consider going to a pair of 6s instead and use the two 12s as cores for that purchace.

Two 230AH 6s like the East Penn GC15s they sell at Can Tire for a good price gets you way more AH than you have now and is likely enough if 255 is good.

https://www.canadiantire.ca/en/pdp/motomaster-group-gc2-6-volt-deep-cycle-golf-cart-battery-0102000p...

Plus a pair of 6s are much better house batts that can actually be deep cycled, unlike typical RV 12s.

A problem might be if the 6s are too tall for your battery compartment. Meaure twice!

[Lwiddis]

Do you need to add another battery or do you need to replace the two you have with quality deep cycle six volt batteries? You must have 12 volt batteries now and most of those are not true deep cycle.

[time2roll]

Yes the existing charging system will work. Need to post the converter model to know if it will work poorly, work well, or work excellent.

Best to match batteries but not critical. Just don't match an AGM with flooded etc. Expect to replace both when the original is headed south.

[phillyg]

Yes, but it's best to match size and age.

[jdc1]

You'll be fine. It will take a little longer to charge them, of course.

[MDKMDK]

ybconway wrote:
If I have room to add another house battery can I just use the existing charging system. Do I have to match the capacity of the two existing house batteries.

If the 3rd battery is being placed close to the others, and you parallel them all together at 12V, should be able to just add the new one. The charging system will just see them as one battery.
Unless you're referring to age/capacity. If the old ones are not in good shape, you might be better off replacing them first.