Battery Advice?

[mgjessop]

Just finished putting up the last of the solar panels on My 34n Fleetwood Fiesta. I have a total of 1200 watts of panels and on a sunny day I am able to put about 55-65amps a hour to the batteries. I currently have 2 6volt 220amp hour house batteries wired in series to make 12volts. It only takes about 2-3 hours of good sunlight to fully recharge them. When we turn out for the night the batteries are right about 12.7 volts and when we wake up they are around 12.1 to 12.2 volts. Here is where I need some advice. I can purchase 12volt 120amp Hour deep cycle RV/Marine batteries by interstate batteries from our local Costco for $68.99ea each, with a 2 year replacement warranty, or I can purchase a 6volt golf cart 220AMP hour battery for $132.99ea with a 1 year warranty. I am thinking about getting 6 of the 12volts for $415 vrs the six 6 volt golf cart batteries for $797. Need some advice from you guys? Thank you

[1mainiac]

If your going to keep up on the maintenance the 6v batteries are the way to go even though some will say you get more power out of the 6 12v batteries. IMHO there is no replacement for displacement and the 6v batteries have much bigger cells and are designed for long term high output use. So while math would say the 6 12v batteries at a total bank of 720AH is better The same logic would say a small block Chevy putting out 500hp would out pull a 400hp Diesel and I bet you know that won't happen. In the end how your going to use and maintain them is the biggest key to getting the right battery for you.

[DieselTech39]

IMO I'd chose the 6 6V in series over the 6 12V in parallel. Almost double the storage capacity....1320 AH vs 720 AH. With solar, storage capacity is what's necessary to use the energy you're generating. Best of luck in your decision.

[mgjessop]

Maybe I am not doing my math correctly.

The 6 volt batteries are 220amp hours but at 6 volts, so when I put 2 together in series do I not get 220amp hours at 12 volts?

If I put 2 12volt 120amp wired parallel, I get 240amp hours at 12 volts?

Tell me if this correct?

6) 6V 220amp = 660amp hours at 12 volts?
6) 12v 120amp = 720amp hours at 12 volts?

Thanks for help.

[1mainiac]

Originally Posted by DieselTech39

IMO I'd chose the 6 6V in series over the 6 12V in parallel. Almost double the storage capacity....1320 AH vs 720 AH. With solar, storage capacity is what's necessary to use the energy you're generating. Best of luck in your decision.

6 of them in series would be 220AH at 36v, 6 of them in Series Parallel would be 660AH at 12v, 6 in parallel would be 1320AH at 6v.

[DieselTech39]

Originally Posted by 1mainiac

6 of them in series would be 220AH at 36v, 6 of them in Series Parallel would be 660AH at 12v, 6 in parallel would be 1320AH at 6v.

3 sets paralell of 2 6V in series is what I meant. Storage capacity of each of them is 220 AH. Why would it become 660AH in a parallel 12V?

[1mainiac]

Originally Posted by DieselTech39

3 sets paralell of 2 6V in series is what I meant. Storage capacity of each of them is 220 AH. Why would it become 660AH in a parallel 12V?

because the 2 in series would only be 220 so you would have 3 banks of 220 in parallel for 660 amps. VS 6 banks of 120 in parallel for 720AH however the 660AH would be a much stronger bank becaus eof cell size.

[1mainiac]

Originally Posted by mgjessop

Maybe I am not doing my math correctly.

The 6 volt batteries are 220amp hours but at 6 volts, so when I put 2 together in series do I not get 220amp hours at 12 volts?

If I put 2 12volt 120amp wired parallel, I get 240amp hours at 12 volts?

Tell me if this correct?

6) 6V 220amp = 660amp hours at 12 volts?
6) 12v 120amp = 720amp hours at 12 volts?

Thanks for help.

Correct

[1mainiac]

What most do not factor in is the effect of cell size allows the 6v batteries to work much harder with less stress and less heat build up which means less water loss and longer life.

[DieselTech39]

Originally Posted by 1mainiac

because the 2 in series would only be 220 so you would have 3 banks of 220 in parallel for 660 amps. VS 6 banks of 120 in parallel for 720AH however the 660AH would be a much stronger bank becaus eof cell size.

I stand corrected....and I found it's Kirchoffs Law.

[Mr_D]

If the batteries say RV/Marine on them they are not true deep cycle batteries, they are a compromise and not the best for either. Also, if they can put out enough amps to start an engine (CCA rating) then they are not deep cycle batteries.

[mgjessop]

Thanks for all the good advice.

[mgscott4]

At Sam's club you can get 6 volt (208 Ah) Energizer battery for $85, or 6 volt (232 Ah) for $112.

[JMacy]

We went with the Costco interstate batteries and have had excellent success with them I go with cheap


Ph.D. Psychology, Applied Sports Psychology