A very specific objective here: A little discussion from folks who have asked themselves the same question.First, the context, we have had two batteries for ~20 years and dry camp from time to time. I wired in an marine battery selector switch. The bottom line is that we almost never used it, and I'm trying to decide if it's really worthwhile to replace it on our new camper.I know someone will suggest we forget about switching and get two 6V batteries.We may do that someday- but given that- through a turn of events, wound up with two new 12V batteries.I'm thinking it might be worth it to simply hook them both up "full time".Any other thoughts or great stories from folks on this subject?

K3WE wrote:I'm thinking it might be worth it to simply hook them both up "full time".Any other thoughts or great stories from folks on this subject?Since there are parasitic loads on the batteries, how do you intend to disconnect?

Yes, put them up together and keep them charged with a solar system. I did that for a couple of years before the twelves aged out.

Theoretically, at least, it is more advantageous to wire them in parallel according to Peukert’s law. In the RVing world having batteries or battery banks wired independently can mitigate the hassle of waking up to no 12 volts due to dead battery, we have not experienced this issue an always paired up our batteries whether 12 volt or 6 volt. No need to go to a pair of 6 volt golf cart batteries if you are seldom off the power grid, wired in parallel your 12 volt jars should give you a couple of days camping with moderate use.

I could see using a battery switch if you could reasonably run down your battery(s) with no means to recharge when needed and wanted to preserve "emergency" power for those situations. Otherwise it's commonplace to just plug em in in parallel and fuggetabouit. You said it yourself, you almost never isolated the batteries in 20 years, so unless the situation has changed, I don't see the need. Example, I have our boat's house battery that runs the amps for the stereo isolated from the starting battery with an automatic relay to preserve that emergency power if needed to start the boat. Camper, if the batteries are run down, fire up the generator and charge em up. Or they get charged (somewhat) while driving as long as the burner in the fridge doesn't blow out.

with two batteries you are half as likely to have dead batteries. lol. Assuming that they are healthy batteries of course.Two is more power, more amps, and less chance the lights will flicker when the water pump comes on.The downfall is that with two 12's they need to be matched and about the same age. If one is a little more gone than the other then it will always be pulling voltage off the slightly better one and the better one will always be drained down to the lesser charge. Thus the 6-volt in series solution.If you use solar then this mitigates the problems greatly.Personally I have two 12 volt systems that can be connected together, but I keep em apart. One is dedicated for the electric cooler fridge/freezer, the other for the coach. I can be without coach power, but that fridge has to stay running. Im sure there are other good reasons to keep batteries separated too.

"A-B" Battery Switch | Good Sam Community

pianotuna
Nomad III
Oct 20, 2019
I added the switches to allow me to equalize the battery banks using solar. So, yes, I need the ability to run from one battery bank while charging the other.
wa8yxm
Explorer III
Oct 20, 2019
Some folks like the concept of the A/B/Both/Off switch because if one or the other battery is having "Issues" isolation is fast and efficient.

Myself.. I'm not among them (I can isolate just fine with my wrench).

As for two 12's in parallel or 2 6s in series

The GC-2 6 volt Golf car battery is a true deep cycle (Can safely to to half full) 220 (giver or take a bit) amp hour set up... so you have 100-120 (Depending on the give or take) amp hours of usable power. Nice

Most 12 volt batteries (the GC-12 is an exception it's the same as above but less capacity) are MARINE/deep cycle. you can only use about 20-25 percent of the capacity safely

Group 24 75 AH
Groups 27 and 29 Just under/over 100
Group 31 130

Give or take a bit in each size depending on maker and model.

Source. Both US battery and Interstate battery

As for how to rig your rig... Up to you.

Some folks like that if one of the 12's in parallel fails. you still have the other one.. I have a mix of 6volt and 12 volt maintenance free. Eventually I'll move to more GC2 and less Group 29.

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