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Old 04-03-2008
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Yet another battery thread

I know there are a few but let me throw one more into the mix.

My current battery set includes 4 6v golf cart batteries (Deka GC15), two each in series, then in parallel. Each battery is ratet 215 amp hours, so the total for this system is 430 AH in 12volts.

It's time to replace these things, as they don't really charge properly anymore. I priced the exact replacement and they go for $120-$140 each.

At the same time, regular deep cycle group 27 12v batteries sell for $80 or so. They presumably have 110AH, so if I connect them in parallel - I should get 440AH for a price that's about half of what I'd pay for the current setup. They are slightly longer, but I should be able to accomodate that (or go a size smaller to 4 group 24, though total hours would be reduced to about 360AH).

Is there any specific drawbacks to using 4 12v batteries that way? Am I missing a particular reason these are so much cheaper?
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Old 04-03-2008
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They're probably not very good 12V batteries. Who makes them??? Cheaper batteries will have thinner plates.
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Old 04-03-2008
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Practically anyone, I guess. I found about the same price on G27 batteries at many retailers - Defender is a first choice, but also various miscellaneous stores on the web. West Marine was, of course, twice as expensive

The ones at Defender are Sportsman Battery. The same brand for the 6v battery costs $120, whereas G27 12v is $80 (both Sportsman sold by Defender)

I think at this point, if there isn't an ovveriding reason to stay with 6v, I'd probably try to save money.
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Old 04-03-2008
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Brak...who is claiming 110ah from a group 27? Are you sure this is a 20hour rating? I think there is some fluff there as typical will be 90 or so.

Anyway...between the pair of 6vDeka's and a Deka marine group27 deep cycles is 10lbs of difference and 35 amp hours. If you are not comparing deka group27 MARINE batteries price-wise...then you are probably looking at thinner plate "dual purpose" batteries which will compromise cycle life.
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Old 04-03-2008
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How much extra weight are u adding with the 12vs vs. the 6v batteries?
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Old 04-03-2008
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no extra weight. actually, some DC27s are a bit lighter, not by much though.
DC27 12v batteries weight between 55-62lbs
6v golf carts of the size I have - 62lbs

I wasn't comparing Deka to Deka. Honestly, Deka's are hard to find - the only dealer around here is a strange guy in a lonely shack. DC27s are sold all over the place.

It does seem that the price difference becomes less if I go to other distributors - Defender is the only place where it is so significant. Not sure what to make of it. If it is Defender's discount - I'd better go for it. If they are selling junk - may be not.

I can definitely forgo perhaps 10-15% of total amp hour capacity for a good deal, I wasn't using even half of it
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Old 04-03-2008
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Ok, here is another comparison.
Sportsman Marine Deep Cycle Wet Acid Batteries

Same manufacturer, so presumably same kind of quality.

DC27 - 12v, 110AH, $127
GC4 - 6v, 220AH, $188

We are talking $60 difference per battery, if I were to select from these two types. I don't get it.
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Old 04-03-2008
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From when I bought 6V batteries vs 12V batteries for my old landyacht RV, have not had to buy house bats for the boat as of yet, the AHR's were different for a 12V vs a 6V. IE the 6V AHrs would be for a higher discharge than the 12V bats, so in reality, the 6V had about 50% more capacity than the 12V of equal wt etc. Then again, my brain may be a bit fuzzy, but I did find 12V to last about half the overall time as a 6V battery.

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Old 04-03-2008
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Marty...in the examples above we are comparing apples to apples in terms of amp hours and rate of discharge. What we are NOT comparing due to lack of data is number of cycles to 50% which can vary greatly and are generally not specified. Many group 27 batteries are lightly built compared to golf cart batteries and this may account for the difference you cite.
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Cam

Glad to know both AHR discharges are the same. At least my brain was not as fuzzy as I thought too.

I would concur that typically 6V bats are able to handle more discharges than a 12V, and with that in mind, the 6V bats may in reality be the better buy in this case. But until those numbers are known, it is a crapshoot as to which is the better option.

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