Is there any benefit to using 6 volt batteries instead of 12 volt?

Coach Dad

I'm getting ready to buy some batteries for my off grid system.

I can buy four 12 volt 100AH batteries for $100.00 less than buying four 6 volt 200AH batteries.

My battery bank will be a 24 volt 200 AH...
So I can wire the 12 volt batteries as 2 series strings in parallel to give me 24 v with 200 AH or I can wire the 6 volt batteries as 1 series string to give me 24 volts with 200 AH...

Is there any reason to spend the extra $100.00 for the 6 volt batteries?

solarix

Re: Is there any benefit to using 6 volt batteries instead of 12 volt?

yes, the less your batteries are in parallel the better. 2 strings in parallel is certainly ok but 1 is better. Also, you have less cells to water with 6 volt batts plus - with batteries in series if (when) you start to have trouble, it is easier to find the bad one when they are in series (under load).

techntrek

Re: Is there any benefit to using 6 volt batteries instead of 12 volt?

I agree, go all series if you can. The 6 volt batteries usually have about twice the amp rating of 12 volt batteries (the individual cells are physically twice as large), so you'll get twice the available wattage from the 6 volt batteries in series. Always think watts when you start comparing total battery bank size and are comparing different voltage batteries. When adding batteries in series, the amps stay the same, the voltage increases.

12 volt batteries = 110 amps each ; 6 volt batteries = 220 amps each (in general)

So when using 12 volt batteries you'll need two batteries to get to 24 volts, @ 110 amps. 110 amps times 24 volts = 2640 watts (really 1320 at 50% depth of discharge). When using 6 volt batteries you'll need four batteries, @ 220 amps. 220 amps times 24 volts = 5280 watts (really 2640 at 50% depth of discharge). To match this battery size with 12 volt batteries you'll need to parallel another string which should be avoided since you can do the same thing with one string using 6 volt batteries.

mike95490

Re: Is there any benefit to using 6 volt batteries instead of 12 volt?

Coach Dad wrote: »

I'm getting ready to buy some batteries for my off grid system.

I can buy four 12 volt 100AH batteries for $100.00 less than buying four 6 volt 200AH batteries.

My battery bank will be a 24 volt 200 AH...
So I can wire the 12 volt batteries as 2 series strings in parallel to give me 24 v with 200 AH or I can wire the 6 volt batteries as 1 series string to give me 24 volts with 200 AH...

Is there any reason to spend the extra $100.00 for the 6 volt batteries?

You are going to spend at least that much, for the extra cables and 2 fuses for the parallel 12V strings. And the 12v "marine" batteries are not really deep cycle like the 6v will most likely be.