2 6-V Batteries in series vs. 2 12-V Batteries in parallel ?

[Dave and Donna]

Hello Fellow MS's -

Just had our friendly RV Doctor over to finish up on a couple of warranty issues.

He has found the two 6-volt batteries [connected in series] that came with our unit are not able to hold a charge.

Could have been I let them run dry over these past 2 years . . . or they have failed for whatever reason.

In any case, the age old question resurfaces.

Should I replace them with 2 new 6-volt deep cycle batteries connected in series or 2 new 12-volt batteries in parallel?

The RV tech recommends the 12-volters, but I thought the 6-volters were preferred.

Your opinion, please,

Thanks,

[rverdlm]

The 6V batteries are far more rugged and will take much more abuse. They also will take many more discharge/recharge cycles. Also if you completely discharge the 12V batteries they will be ruined whereas the 6V batteries handle this without problems.

[Motor31]

The advantage to two 12 volt batteries is this. In the event that one fails you can simply cut it out of the circuit and you still have another 12 volt battery you can use. Having said that, the 6 volt batteries are heavier and you can generally get more amp hours from a pair of them than a pair of 12 volt batteries.

This is all predicated on what you plan to do with your rig. If you plan to stay at a park almost all the time (like we do) and dry camp a minimal time I'd go with two 12 volt batteries since it's generally a bit cheaper and they are easier to find (wally world etc.) If you plan on dry camping a good part of the time and will exercise the battery bank, possibly charging with solar or wind go with a 4 battery bank of 6 volt batteries. Trojan golf cart batteries are highly recommended but very very heavy and will require modification to the rig to hold them all.

Either way make sure you maintain the batteries, keeping terminals clean and water topped up about every 3 months or so. They should last 3 to 5 years that way minimum.