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Old 07-11-2018, 12:47 PM   #1
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Another battery question

Hi to all,
Hopefully soon we will be building a new battery bank using 6 volt golf cart batteries. The question arouse as to the advantages and disadvantages there are using 4 lower AH batteries or two higher AH batteries.
I could not answer it. Any insights ?
Thanks
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Old 07-11-2018, 12:52 PM   #2
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Space/weight savings if only 2 batteries. Less cables also.
These are the one I can obviously see as advantage.

L
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Old 07-11-2018, 01:06 PM   #3
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Different Ah, like 8D verses 2GC?


Smaller battery pros: Easier to carry. Availability.
Smaller battery cons: More connections to clean and check, more holes to water.


Large batteries: opposite of above.
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Old 07-11-2018, 02:38 PM   #4
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I don't quite understand your question. GC batteries come in two varieties: GC1 and GC2. The GC2s have slightly more AH capacity but only about 5-10% more The dimensions are the same and the weight of the GC2 is slightly more due to more lead.

You can get much bigger (and taller) 6V batteries like L16s which are used in floor polishers which have about double the AHs and double the weight. But I suspect that simple GC1 or GC2s give you the most AHs for the buck.

Finally very few 12V 8Ds are true deep cycle batteries like golf carts. And they are back breakers.

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Old 07-11-2018, 06:32 PM   #5
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I would go with 4 GC batteries over 2 L16’s. I have 8 L16’s because I have only enough foot print for 8 batteries but no height limitations.
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Old 07-11-2018, 09:51 PM   #6
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I have 4 L16 AGM batteries. Each has a claimed Ah capacity of 390 Ah for a total bank size of 780 Ah.

One of the reasons I went with this combination was the desire to get as much capacity in the available footprint. The other reason was I found a great price on the L16 batteries.

I would go with the combination that will give you the most battery capacity for the best cost. Often, that is the GC batteries.
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Old 07-12-2018, 05:55 AM   #7
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One advantage of GC2’s is ready availability. If one goes bad, you can replace it as fast as you can get to a Sam’s Club. When I was deciding on redoing my battery banks, Rolls quoted me 8 weeks for delivery of an 8D; I went with GC2’s again for the house bank, and 3 Group 34’s instead of 2 8D’s for the start bank.
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Old 07-12-2018, 07:57 AM   #8
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Quote:
Originally Posted by Gordon B View Post
Hi to all,
Hopefully soon we will be building a new battery bank using 6 volt golf cart batteries. The question arouse as to the advantages and disadvantages there are using 4 lower AH batteries or two higher AH batteries.
I could not answer it. Any insights ?
Thanks
I'd offer that when building a bank, bigger IS better. Refer to information on the peukert effect. Simplified, for a constant amp draw, a larger bank will yield a disproportionately higher capacity than a smaller bank. Then there's the DOD (depth of discharge) to factor in. Battery life is not measured in time, but in cycles, each discharge/recharge being a cycle. If you look at the manufacturers' ratings, you'll see that the same battery is rated for more cycles at a lower DOD. For example, a battery may be rated for 1500 cycles at 50% DOD, and 2000 cycles at 35% DOD. Each manufacturers' spec will vary, but all will follow that basic profile. So for a given load, a larger bank will result in lower DOD, with the end net that it will deliver more cycles, ergo, a longer lifespan.

So it's good to know with some degree of accuracy your daily energy use in order to build the bank that will provide that with the lowest manageable DOD. Remember, with lead acid you're only utilizing half of the rated capacity.
You'll rarely hear the complaint that "my battery bank is just too big...." The bank is part of the system, assess the SYSTEM of which the battery is just one piece.
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Old 07-12-2018, 08:00 AM   #9
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Post #8: +1
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Old 07-12-2018, 10:05 AM   #10
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Quote:
Originally Posted by Gordon B View Post
Hi to all,
Hopefully soon we will be building a new battery bank using 6 volt golf cart batteries. The question arouse as to the advantages and disadvantages there are using 4 lower AH batteries or two higher AH batteries.
I could not answer it. Any insights ?
Thanks

If you have only two 6Vs wired in series to a 12V bank... and one goes bad... you've got squat.

If you have 4 or more 6Vs wired in series/parallel for a bank, if one battery goes bad, you may still have a relatively easy get-home option.

Given druthers, think I'd rather combine your choices: four or more batteries, higher AH each to the extent possible, space permitting, etc.

-Chris
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Old 07-12-2018, 10:41 AM   #11
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ranger42c Post #10

+1
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Old 07-12-2018, 12:19 PM   #12
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Bigger is always better when it comes to battery bank AH. I think GC batteries make an excellent house bank. If you have the room, go for the most AH you can fit. No one ever said "this battery bank lasts too long."

Ken
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Old 07-12-2018, 02:10 PM   #13
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Thanks everyone
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