"Deep cycle" AGM?

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RandomJoe
RandomJoe Solar Expert Posts: 472 ✭✭✭
in Solar Beginners Corner #1
I was at Batteries Plus buying a couple small AGMs for my kayak lights today and noticed something I'd not seen before.

For several sizes of batteries (very small - 5AH, 7AH, that sort) they had two model numbers of otherwise-identical battery. (Actually the model numbers were mostly identical too, just the last digit different.) One was simply labeled as an "AGM" the other "Deep Cycle AGM".

So I know the difference between a starting and deep-cycle flooded and thought I knew - perhaps just assumed? - that a real deep-cycle would generally be larger due to the thicker plates.

Are these little "deep cycle AGMs" really something different, or are they just labeling / marketing? I believe they were the same price too, now I think about it.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
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    Re: "Deep cycle" AGM?

    hard to say. did you try asking the guy at the counter about it on the remote chance he knows something? i believe if it is one of their typical werker batteries then it's all chinese anyway and we know that's a bit iffy. any of their batteries only lasted me 1-2yrs no matter what.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #3
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    Re: "Deep cycle" AGM?
    RandomJoe wrote: »
    I was at Batteries Plus buying a couple small AGMs for my kayak lights today and noticed something I'd not seen before.

    For several sizes of batteries (very small - 5AH, 7AH, that sort) they had two model numbers of otherwise-identical battery. (Actually the model numbers were mostly identical too, just the last digit different.) One was simply labeled as an "AGM" the other "Deep Cycle AGM".

    So I know the difference between a starting and deep-cycle flooded and thought I knew - perhaps just assumed? - that a real deep-cycle would generally be larger due to the thicker plates.

    Are these little "deep cycle AGMs" really something different, or are they just labeling / marketing? I believe they were the same price too, now I think about it.

    Well, thicker plates would make the battery larger if the total plate surface area was the same (as would be expected for the same AH rating).
    But you can also get better deep cycle behavior by changing the composition (alloy) of the plates without making them thicker. Especially for something like an AGM geometry where the plates do not have to support their own weight.
    SMA SB 3000, old BP panels.
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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #4
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    Re: "Deep cycle" AGM?
    RandomJoe wrote: »
    Are these little "deep cycle AGMs" really something different, or are they just labeling / marketing? I believe they were the same price too, now I think about it.

    It all depends on the reliability of the manufacturer / retailer. For example, Powersonic makes some quality batteries, and have different ranges depending on whether you want general purpose, high-rate discharge, long standby/float usage, or deep cycle with heavier plates. (PS, PSG. PHR, PDC etc etc)

    Powersonic's PDC designation is the deep-cycle range with heavier plates and heavy duty active material paste. At a casual glance they all look pretty much the same so it pays to know your manufacturer's offerings. A decent manufacturer also provides quality documentation and application manuals to help you choose properly.

    You'll also see lettering depicting common terminals such as F1/F2 (slide on), NB (nut and bolt) and so forth.

    Note that these lead-calcium agm's in these smaller ranges aren't the only game in town. Often overlooked are the Enersys/Hawker Cyclon sla's that are baby versions of their pure-lead bigger brothers like the Optima and Odyssey agm's. Highly recommended as they will take a huge amount of current as long as you can supply .4C minimum, which usually isn't a problem with these smaller sizes. I prefer these to all others, although you may have to string a few together in either the individual 2v cells, or a few 6v "monoblocks" to get the voltage you need.
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