Adding two 6v to two 12v?

[judelaurenzo25g]

Hi All,

We just moved from a 5th wheel toy hauler to a new class A motorhome. I'm not sure if I should do another set of 12's or add 6's in series. In an ideal world I would swap out all to 6v's but that's not an option. What are you thoughts on this?

Thanks,
JL25g

[judelaurenzo25g]

wa8yxm wrote:

time2roll wrote:
You can spring for a new Class A but putting a matching set of batteries is not feasible?

Well I did not afford my Class A by throwing out perfectly good stuff (Wasting money) and I know for a fact that so long as they are in Parallel not series. batteries need only match on one parameter VOLTAGE. Batteries will work out all the other differences. You can parallel a aaa aaaa c and D battery and they will work it out.

Same with a Group 24 27. 29 31 and a pair of GC2. they will work it out. 100% guaranteed.

I'm not cheap but I'm trying to follow your lead and not throw money away. I've done lots of that in my younger days.

[judelaurenzo25g]

RJsfishin wrote:
I don't know what you're expecting to gain from 2 6v over 2 12v, both being deep cycle. And BTW, 12v RV marine / trolling motor batteries are deep cycle batteries, despite what "know it alls" lead you to believe.

Buy 2 new 12v batteries same as the existing 2, and you will be happy.
You will not notice any difference if you go to 6v, if you discharge to 50%

Thanks for the advice, I was leaning this way and decided to do exactly what you're suggesting.

[judelaurenzo25g]

time2roll wrote:
You can spring for a new Class A but putting a matching set of batteries is not feasible?

If you read the whole post you would have seen that money isn't the issue. I just didn't want toss out two new 12v. I am adding two more batteries so I would have a total of 4. I was trying to figure out if adding two 6 would work with the 12v ok.

[pianotuna]

Here is the best resource for connecting batteries in parallel.

http://www.smartgauge.co.uk/batt_con.html

[3_tons]

RJsfishin wrote:
I don't know what you're expecting to gain from 2 6v over 2 12v, both being deep cycle. And BTW, 12v RV marine / trolling motor batteries are deep cycle batteries, despite what "know it alls" lead you to believe.

Buy 2 new 12v batteries same as the existing 2, and you will be happy.
You will not notice any difference if you go to 6v, if you discharge to 50%

Not trying to be one of those nasty ‘Know-it-alls” but one should be advised that not all 12v as advertised ‘deep cycle’ batteries are truly deep cycle, many are actually hybrid designs to allow for boat engine cranking...A true deep cycle can cycle below a 50% state of charge without long term damage...

3 tons

[wa8yxm]

time2roll wrote:
You can spring for a new Class A but putting a matching set of batteries is not feasible?

Well I did not afford my Class A by throwing out perfectly good stuff (Wasting money) and I know for a fact that so long as they are in Parallel not series. batteries need only match on one parameter VOLTAGE. Batteries will work out all the other differences. You can parallel a aaa aaaa c and D battery and they will work it out.

Same with a Group 24 27. 29 31 and a pair of GC2. they will work it out. 100% guaranteed.

[RJsfishin]

I don't know what you're expecting to gain from 2 6v over 2 12v, both being deep cycle. And BTW, 12v RV marine / trolling motor batteries are deep cycle batteries, despite what "know it alls" lead you to believe.

Buy 2 new 12v batteries same as the existing 2, and you will be happy.
You will not notice any difference if you go to 6v, if you discharge to 50%

[wa8yxm]

Well I was being a bit "Sarcastic" with the word "Slight" I agree double the usable capacity is a BIG difference.

Also in the 9 years my Original Interstate GC-2's lasted I "OOPSED" a few times. what is an OOPS. Down so far even ther light won't light. Most of those were Early on. and the Replacement Deka' been OOPSED one time but that was not my fault. (Converter died).

MARINE/deep cycler and Starting batteries generally do not recover well from that kind of a VERY DEEP discharge.

[time2roll]

You can spring for a new Class A but putting a matching set of batteries is not feasible?

[theoldwizard1]

wa8yxm wrote:

By the way there is a slight difference between most 12 volt (MARINE/deep cycle) and most 6V (Golf Car/DEEP CYCLE) batteries. the way I type it suggests.

MARINE/deep cycle you can safely use about 25% of the capacity. run 'em down to say 25% SOC and the odds of recovery are... SLim (not none but clearly slim)

DEEP CYCLE you can safely use 50%. Run 'em down to 25% SOC and odds are good they Will Recover (not 100% but way better than the MARINE type).

I would not call that a "slight difference" !

I happened to have had an email conversation with Trojan about this topic (The T-1275 is a true deep discharge 12V "golf cart" battery; The SCS225 is more of a "dual purpose" battery, one of the the few that Trojan actually lists "Cold Cranking Amps" for.)

James M. Cobb Technical Support Engineer Trojan Battery Company wrote:
The T-1275 is a higher capacity battery, rated at 150 Ah where the SCS225 is rated at 130 Ah. The T-1275 is a heavy duty 12V golf cart battery with thicker plates, which means it has a longer cycle life at 50% DOD, 1200 cycles versus 600 cycles for the SCS225.

Oh, the T-1275 weighs 85 lbs and the SCS225 weighs 66 lbs. The T-1275 is BCI Group size GC12 and the SCS225 is BCI Group Size 30H, so they are not physically the same exterior size.

[wa8yxm]

Thanks for the support BD.

By the way there is a slight difference between most 12 volt (MARINE/deep cycle) and most 6V (Golf Car/DEEP CYCLE) batteries. the way I type it suggests.

MARINE/deep cycle you can safely use about 25% of the capacity. run 'em down to say 25% SOC and the odds of recovery are... SLim (not none but clearly slim)

DEEP CYCLE you can safely use 50%. Run 'em down to 25% SOC and odds are good they Will Recover (not 100% but way better than the MARINE type).

By the way I run both types in parallel here one pair of GC-2's (DEKA G-20s) and 3 Group 27 MARINE/deep cycle so I know what I'm typing about.

[ScottG]

judelaurenzo25g wrote:

theoldwizard1 wrote:

edbehnke wrote:
remeber batteries always go to the weakest battery. heck, just replace them all.

Concur !

Limp along on what you have until you have the funds to do them all.

It's not about funds. I just don't want to wast 2 new 12v batteries.

And you don't need to. In real life those two twelves will work just fine.

[pianotuna]

Hi,

Make sure to brace the floor on the compartment. An rv going down the road dragging the house battery bank on the pavement would not be a pretty sight.

judelaurenzo25g wrote:
6's will fit, I am moving my battery bank to the empty storage compartment next to my stairs (where they are located now). I could probably fit 10 batteries in that compartment if I wanted too, but weight would be a problem. I will add a few vents to the compartment to let gasses out.

[BFL13]

Since the 12s are new, you can get new 6s or new 12s to go with them.

If you choose 6s, the way I bank them is as two big 12s instead of as three 12s. That is, first put the two 12s in parallel then parallel that pair with the two 6s (in series) Now put your load/ charging wires on so that the pos go on one pair and the neg on the other pair.

You can parallel different AH size batteries with no issues at all. What counts is if they are in different conditions as with an old worn battery and a new one.

If you don't find it convenient to bank them all for loading and charging, you can have more battery by using a separate bank for your inverter and another bank to run the rest of the rig.

That way you can have two banks in different conditions and they won't be in parallel. You just need a way to charge each bank, which is not rocket science to arrange.