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Old 22-10-2012, 20:59   #1
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Group 31 deep cycle robust like GC batteries?

Hi:

Here is the scenario. I have an Ontario 32 with two house batteries and one starter battery in the nav station seat. No battery boxes or restraint, and a complete rats nest of wires going to the terminals under wing nuts. I can't check the water levels without removing the wiring in the whole compartment. This install is clearly broken on so many levels.

I have made a WAG of my daily A-h requirements, and I would like to be able to survive 3 consecutive cloudy days (that is solar is the preferred energy source) before resorting to fossil fuel charging while away from shore power. This leads to about doubling the house battery size into the 400 to 500 A-h range.

My impression is that it is real hard to beat golf cart wet cells in terms of their deep cycle robustness, favorable cost, and life span, as long as one is willing to do the required maintenance. Four of these would be my solution except for the fact that I would like my house battery set to be located in the bilge. GC batteries won't fit in the height dimension.

I am about 80% sure I can get four group 31s down there, and about 99% sure I can get four group 27s down there. I would likely make custom GRP battery boxes to implement this solution.

My question after all the above, is do batteries of equal deep cycle performance to GC batteries exist in either group 31 or 27 form factor, and if so, what makes are recommended? I ask because I have the impression that so called deep cycle batteries in these sizes are usually dual purpose and not as robust as true deep cycle batteries. I am particularly interested in what I might actually find in Ontario.

If nothing exists similar to GC, then I would consider some alternatives. I have not actually pondered access yet, but choice 1 might be to go with batteries accessible from the port lazarette, but this is likely to have weight distribution and access issues. Choice 2 might be AGMs mounted not vertically in the bilge, but I don't like the cost and other negatives of AGMs. Choice 3 might be take whatever is on offer in Group 31 wet cell even if not a really good deep cycle battery.

Thanks for input.

Cheers

Boulter
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Old 23-10-2012, 05:06   #2
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Re: Group 31 deep cycle robust like GC batteries?

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Originally Posted by Boulter View Post
... do batteries of equal deep cycle performance to GC batteries exist in either group 31 or 27 form factor ...
Not likely.
Check out the 20 Hr discharge rates for various batteries.
http://www.trojanbattery.com/pdf/TRJ...dSpecGuide.pdf
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Old 23-10-2012, 05:39   #3
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Check out Lifeline golf cart 6volt AGM the 4CT model. Footprint height is less than 10 inches. 4of them gives you 440 a h. Make sure you ave capability to charge bvacks to 100 % frequently as that will prolong AGM life. We have 6 of these for our house bank.

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Old 23-10-2012, 07:21   #4
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Re: Group 31 deep cycle robust like GC batteries?

I realize that you don't like the high cost of AGMs. But that is the only way you are going to get almost the same capabilities of GCs in a GRP 31 size. As others have noted, there are no true deep cycle flooded cell AGMs.

David
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Old 23-10-2012, 15:55   #5
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Re: Group 31 deep cycle robust like GC batteries?

Quote:
Originally Posted by GordMay View Post
Not likely.
Check out the 20 Hr discharge rates for various batteries.
http://www.trojanbattery.com/pdf/TRJ...dSpecGuide.pdf
Hi Gord and others:

Thanks for the responses and (Gord) the link.

I don't understand your point. I reviewed the table and though not group 31, the group 30H batteries 31XHS are for my purposes the same in width and height as the group 31 figures I was using from the Defender catalog. Are these batteries not of equivalent robustness to the T105s? They are both described as "Deep Cycle Flooded Batteries with T2 Technology (TM)".

I went and had a real good look today. The available height grows (or more accurately the 7 1/8" width point drops) as I move forward towards the mast step. There is even a chance I might sneak four GC batteries in there with enough finesse and luck (and maybe a bit of grinding out some hull roughness). Though not likely the Trojans which are 10 7/8", but maybe another brand listed at 10 1/2" tall.

Given a battery width of 7 1/8" which is both the group 31, 30H, and GC2 form factors, this idea falls to pieces at some height around 10" to 10 1/2". What can I get away with ...

Thanks again guys.

Boulter
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