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Open Roads Forum  >  Tech Issues

 > Adding two 6v to two 12v?

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theoldwizard1

SE MI

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Posted: 01/08/19 04:05pm Link  |  Quote  |  Print  |  Notify Moderator

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.

wa8yxm

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Posted: 01/08/19 04:12pm Link  |  Quote  |  Print  |  Notify Moderator

I would never get rid of perfectly good 12 volt batteries.

But I want you to think of this... And I will explain it
There are no SIX VOLT batteries in RVs.. (Even if I can clearly see two of them under my steps).

WHY
Well

If you have a 12 volt battery you have

-{12 volt battery}+ 12 volts

And if you have 6 volt pairs you have
-{6v}+-{6v}+ 12 volts

As you can see the two six volt in SERIES become.. a 12 volt battery.

Think of them that way
Can I put a 12 volt battery in parallel with 2 more 12 volt batteries? YES
Can I replace 1/2 of a 12 volt battery and not the other half (NO)
Must both halves be the same (Age/Make/Model/Size) yes

But see how easy the questions get when you think of your pair of 6vs as a single 12?


Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377


judelaurenzo25g

Downey, CA

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Posted: 01/08/19 04:18pm Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

I would never get rid of perfectly good 12 volt batteries.

But I want you to think of this... And I will explain it
There are no SIX VOLT batteries in RVs.. (Even if I can clearly see two of them under my steps).

WHY
Well

If you have a 12 volt battery you have

-{12 volt battery}+ 12 volts

And if you have 6 volt pairs you have
-{6v}+-{6v}+ 12 volts

As you can see the two six volt in SERIES become.. a 12 volt battery.

Think of them that way
Can I put a 12 volt battery in parallel with 2 more 12 volt batteries? YES
Can I replace 1/2 of a 12 volt battery and not the other half (NO)
Must both halves be the same (Age/Make/Model/Size) yes

But see how easy the questions get when you think of your pair of 6vs as a single 12?


So from what I read here. I'm better off getting two 12v same size and capacity because the 2-6v won't match up in size. Correct?


A ship in harbour is safe, but that is not what ships are built for.


Boon Docker

Mountain Foothills of Southern Alberta

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Posted: 01/08/19 04:18pm Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

I would never get rid of perfectly good 12 volt batteries.

But I want you to think of this... And I will explain it
There are no SIX VOLT batteries in RVs.. (Even if I can clearly see two of them under my steps).

WHY
Well

If you have a 12 volt battery you have

-{12 volt battery}+ 12 volts

And if you have 6 volt pairs you have
-{6v}+-{6v}+ 12 volts

As you can see the two six volt in SERIES become.. a 12 volt battery.

Think of them that way
Can I put a 12 volt battery in parallel with 2 more 12 volt batteries? YES
Can I replace 1/2 of a 12 volt battery and not the other half (NO)
Must both halves be the same (Age/Make/Model/Size) yes

But see how easy the questions get when you think of your pair of 6vs as a single 12?


And there is your 12v lesson for the day. Stay tuned for another lesson tomorrow. [emoticon]

judelaurenzo25g

Downey, CA

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Posted: 01/08/19 04:50pm Link  |  Quote  |  Print  |  Notify Moderator

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.

BFL13

Victoria, BC

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Posted: 01/08/19 05:33pm Link  |  Quote  |  Print  |  Notify Moderator

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.


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pianotuna

Regina, SK, Canada

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Posted: 01/08/19 05:42pm Link  |  Quote  |  Print  |  Notify Moderator

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.



Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

ScottG

Bothell Wa.

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Posted: 01/08/19 09:08pm Link  |  Quote  |  Print  |  Notify Moderator

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.


Scott, Grace and Wesly
2003 Dodge 3500 4x4, 6 speed Cummins.
2018 Silver Fox 32A.
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wa8yxm

Wherever I happen to park

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Posted: 01/09/19 07:15am Link  |  Quote  |  Print  |  Notify Moderator

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.

theoldwizard1

SE MI

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Posted: 01/09/19 09:28am Link  |  Quote  |  Print  |  Notify Moderator

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.

* This post was edited 01/11/19 10:53am by theoldwizard1 *

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