6 volt vs 12 volt

Dont wire 2 12v in series.

The 6s in series are best for deep cycle.

Bill

The 6 volters wired in SERIES will give better service then 2 12 volters in parallel.
Of course this is based on standard group 24 or 27 batteries.

Starting and most 12V batteries have six 2V cells wired in series. To fit six cells in the space of the battery housing, the plates have to be somewhat thin. This gives a lot of surface area relative to the volume of the battery. Surface area = high amps.
This also gives each lead plate less volume relative to its surface area.
Volume = length of discharge over time, so the 12V has shorter discharge time.

The 6V has only 3 cells in the entire battery housing. It can have really thick plates (which most deep cycle/golf cart batteries have). Lower surface area = lower amps, but much, much longer discharge time.

(You therefore have to put two 6V batteries in series to get 12V. You don't add amps in series, so two 225Ah batteries in series gives you 12V at the same 225Ah.)

I am assuming you meant to say two 6VDC Batteries in series and two 12VDC batteries in parallel... Consider these pictorials
Typical wiring for both battery groups



Two 6VDC batteries in SERIES - Connecting two in series doubles the OUTPUT DC OUTPUT VOLTAGE - The RESERVE POWER will only be the same as ONE 6VDC Battery.


Two 12VDC Batteries in PARALLEL - Connecting the two in PARALLEL keeps the same DC OUTPUT VOL:TAGE - The RESERVE POWER will be doubled connecting these in parallel


It really comes down to cost. 6VDC 220AH batteries can be purchased from COSTCO/SAM CLUB for around $80 each. The Reserve Power for this battery is typically 440 minutes (7.3 Hours) meaning this group setup should produce 12VDC @25AMPS for around 3.6HR before dropping to 50% charge state.

The cost of 12VDC 220AH batteries is not going to be cheap. You can get a 12VDC 85AH Battery for around $80 most anywhere. The RESERVE POWER for a 12VDC 85AH battery is 140 minutes (2.3 Hours) meaning this battery group will only produce 12VDC @25 amps for around 1 hour before dropping to 50% state of charge. Having two in parallel will increase this to around 2 hours of time.

Hope this helps deciding which is better for you.

Roy Ken

Hi,

There are lots of myths about six volt vs twelve volt.

What matters most is total capacity in amp-hours.

Wiring needs to be properly balanced for the battery bank.

Get the 6 volt. Long term you will be better served.

The only downsides are that you have to buy them and replace them in pairs, they weigh more (actually a good thing, but has to be considered), and finding boxes to fit.

Listen to Roy B. He's our resident expert on RV battery power, and he helped me when I was looking to upgrade. Have been happy for the last couple of years after going with his advice and getting the two 6 volts.

Lots of good advice on batteries and how to connect them both properly and efficiently. No one mentioned cutting your load on them. Before going out and spending big bucks on four 6v Trojans (or whatever) first spend small bucks on an amp meter to measure what you've got now, then convert all the lighting you'll be using to LEDs. I think you'll be shocked by the difference just doing this alone. Then measure the current draw when you do turn other things on (fans, furnace, DC TV, etc.). You'll quickly figure out what can be used and for how long.

Once you've an idea of what you want to be able to use, you can figure out how many amp hours you'll need for the number of days you want to dry camp and if you really need to get four batteries, two or more solar panels & all that stuff. (IMHO a generator is not how you want to charge batteries.)

The charging system will prove more important than the choice between 12v & 6v.