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Old 04-07-2015, 05:52 AM   #51
ranger58sb
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Quote:
Originally Posted by angus99 View Post
The AGMs are also appealing for relative lack of maintenance, no spills and low discharge over winter (if you don't lave them connected to parasitic loads like I did). Is there any real performance/longevity advantage in the golf cart batteries vs these AGMs (which are rated at 245 ah each) or is the difference primarily weight and price?

From reading, 6v golf cart batteries are said to be true deep cycle batteries, whereas 8Ds are almost always said to be really dual-purpose -- even if the label says "deep cycle." Different design in the GCs, thicker plates, better for deep cycling.

Pairs of 6v GCs at 12v usually give you about 220 Ah/pair. If four will fit where one of your current 8Ds fits, it'd be ~440 Ah vs. ~245 Ah. Or if six will fit where a pair of your current 8Ds fit, that be ~660 Ah vs. ~490.

No spills is an AGM (and gel) feature, as is reduced (not eliminated) off-gassing. Low self-discharge rate is also a feature that I've confirmed with our AGMs over winter. No maintenance is a good thing. OTOH, a flooded lead acid (FLA) system with a battery hydration system installed may be way less expensive.

To compare costs, you'd ideally look at cycle life specs (as in cycles to 50% depth of discharge/DoD), and work out cost/Ah for the whole (predicted) life of a given bank. From reading, FLA GCs (e.g., Trojan T-105s) give you about the best bang for the buck (unless you buy brand X from Costco).... but I still prefer the AGMs. (And BTW, Lifeline makes 6v AGMs; maybe others do, too.)

There are "premium" AGMs (Odyssey, Lifeline, etc. -- and Sears Platinum G31s are made by Odyssey) and then there are the others (Deka and so forth). The former often say stuff about "pure lead" (not recycled) in their products. Dunno whether you can use their marketing words to compare. Probably still safer to compare using cost/Ah over the predicted life of the battery.

Our oldest bank of 3x Odyssey G31 AGMs is now entering it's 10th season.

-Chris
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