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Old 10-05-2014, 11:24 AM   #1
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Coach Batteries 12V to 6V...

Hi All!

I have a 1999 Airstream DP Motorhome with a 2000W inverter/charger. There are four 12V coach batteries which I need to replace. Can I replace with four 6V batteries to achieve equal service?

Thanks in advance for your assistance!

V/r
Steve
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Old 10-05-2014, 11:51 AM   #2
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You would need 8 6volt bTteries to replace 4 12volt batteries.
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Old 10-05-2014, 11:59 AM   #3
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Coach Batteries 12V to 6V...

Quote:
Originally Posted by campersRus View Post
Hi All!

I have a 1999 Airstream DP Motorhome with a 2000W inverter/charger. There are four 12V coach batteries which I need to replace. Can I replace with four 6V batteries to achieve equal service?

Thanks in advance for your assistance!

V/r
Steve

To be accurate would need to know size and type of existing batteries.

Example: group 27 105 amp hour


If this is approx what you have, then you have combined 420 amp hours capacity now.
Replacing with 4 GC2 220 amp hour would yield combined 440 amp hours (slightly more
capacity than you have now)

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Old 10-05-2014, 04:17 PM   #4
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Sorry it is Group 27.

Thanks folks for the info. I didn't believe you could replace one for one with 6V's...just had to check my sanity. I will replace with 4 GC2 series batteries.

Again, Thanks!
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Old 10-05-2014, 05:20 PM   #5
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Originally Posted by campersRus View Post
Sorry it is Group 27.

Thanks folks for the info. I didn't believe you could replace one for one with 6V's...just had to check my sanity. I will replace with 4 GC2 series batteries.

Again, Thanks!

Whoa..... The wiring will be a little different, but the amp hours should be the same.

Two 6 volts need to be wired in series to make 12 volts,

Then wire the other two in series ......then finally wire the two sets in parallel.


Just think of the two 6 volts in series as a great big 12 volt battery in two pieces.

Read this.... It will help

http://www.marxrv.com/12volt/12volt.htm
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Old 10-05-2014, 05:30 PM   #6
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Your current configuration is on the left side of the picture, and what you want
to move to is on the right side.

Click image for larger version

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Old 10-05-2014, 05:49 PM   #7
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Quote:
You would need 8 6volt bTteries to replace 4 12volt batteries.
Not really. 4 x GC2 6v's will produce more amp-hours than 4 x Group 24 or Group 27 12v's and the same amp-hours as 4x Group 29/31 12v's. About 460 AH total.
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Old 10-05-2014, 06:10 PM   #8
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Quote:
Originally Posted by Denniscw View Post
You would need 8 6volt bTteries to replace 4 12volt batteries.

You sir.... Just flunked math class.

The proper answer is: NOT ENOUGH INFORMATION.
Here is why (And the info the OP needs to pass math class)

The most common six volt battery is the GC-2 Golf car battery, depending on just where adn what you buy these run around 220 amp hours give or take about 5 percent, so we can use 220 or 230 as our amp hour rating for each pair..

(Each pair of six volt makes one BIG 12 volt battery, and please think of the pair as a single 12 volt, makes life (Well explanations) so much easier)

Now. IF you existing 12 volt are size 4D: Then Dennis is right, What are the odds of them being 4D? (Approach zero)

Here are some common 12 volt battery sizes,

Group 24 about 75 ah each so 4 of them is 300 amp hours
If you replace with 4 GC-2 (Same tray but taller) that's 460 AH, so that is over 175% the power at the first pass (it gets better)

Group 27 is about 95 amp hours so times 4 it is 380 You are still better with GC2

Group 29 is around 105, Times 4 is 420 and you are still better with GC-2

Group 31 is 130 times 4 is 520 and that beats 4 GC-2.

Source: assorted battery maker web sites. NOTE that capacities do vary slightly from brand to brand and sometimes from model to model within the brand.. Note also all capaciteis listed are at teh C/20 (20 hour) rate.

And from the above, you can find the answer which is

Yes, Yes, Yes, NO for most battery sizes.

Oh, I mentioned first pass

DEEP CYCLE batteries such as the GC-2 Golf car are designed to take a 50 percent discharge (Discharge to half full) and back without seriously shortening the battery's life, they stand a fair chance of surviving even deeper discharges.

MARINE/Deep cycle are first and formost starting batteries, by the time you get down to 50 percent you are already doing damage, they are not designed to go that low.

Unless you get Group 31 TROLLING batteries (not marine/deep cycle) this changes the answers to all yes.
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Old 10-05-2014, 07:35 PM   #9
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WOW! Thanks guys...this is great info! The article is excellent! I must admit that I got myself a little confused above

The battery bank on the coach is fairly old...not maintaining a charge very long. I wanted to switch to 6V's for better service but didn't have any expansion room.

Thanks so much for the article and wiring diagram...very much appreciative!

Steve
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Old 10-17-2014, 10:41 PM   #10
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We have a Winnebago 38j adventurer and would like to replace 2 12 volt batteries with 2 6 volt batteries. I know I need to wire in series, but the problem is now there are two positive and two ground connections how would I wire these to the two 6 volt wired in series with only one positive and one ground??
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Old 10-17-2014, 10:57 PM   #11
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Quote:
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We have a Winnebago 38j adventurer and would like to replace 2 12 volt batteries with 2 6 volt batteries. I know I need to wire in series, but the problem is now there are two positive and two ground connections how would I wire these to the two 6 volt wired in series with only one positive and one ground??
Think of 2 6V batteries as being 1 12V battery. They are connected together + to -, like the top two batteries in the diagram on the right above.
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Old 10-18-2014, 01:48 AM   #12
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Scotty I understand two six volts being like one big twelve volt. But my coach has two positive and two negative cables going into the coach. Currently each twelve volt battery is conected separately to one positive and one negative.
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Old 10-18-2014, 01:50 AM   #13
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After rereading my original post it wasn't very clear. Sorry
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Old 10-18-2014, 03:11 AM   #14
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You need to trace the wires. Probably the 2 neg and 2 pos cables each go to the same place. You would remove one set as in 1 pos and 1 neg cable from where they connect together. You also will need a short cable to go from the pos of 1 six Volt to the neg of the second 6 V battery. F

FWIW I would also check the wire sizes for the existing cables. I might replace all the cables with a size larger depending on the expected load. In essence the designer could assume splitting the load between the parallel batteries and save a buck by undersizing the cables for the total load. My clue would be looking at the junction point. If you have 2 smaller cables going to a terminal block or relay with a larger cable exiting I would assume that was going on.
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