Limit to long-term storage of AGM batteries

LBergman
LBergman Solar Expert Posts: 42 ✭
in General Solar Power Topics #1
This is a theoretical question I've been kind of wondering about off and on, but not too sure of the answer.

Lead acid batteries seem to die from two things (assuming proper care):
1) Cycling
2) Aging

If one was keep some new AGM batteries (a good brand, like MK/Deka) on a float charge and stored at 50-60 deg F, I'm curious as to how long they would remain usable (say, at least good for 1,000 cycles at 80% DOD). By keeping them on float, you would be eliminating the cycling issue so that would only leave aging.

Taking it a little further, if you kept the batteries on float but stored them at 20-30 deg F, how long would they last? The lower temperature should slow the aging as well I would assume, since it does for other battery types.

Really just curious how long one could potentially store these batteries under ideal conditions.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: Limit to long-term storage of AGM batteries

    You are going to have to ask a battery mfg for the answer, but my best guess would be not to store for more than 5 years. I think the lead hardens onto the plates and becomes harder to charge and discharge. Supposedly, you are supposed to cycle backup batteries at least 1 or 2x a year, to keep the lead active. (this is not sulphating - that happens when a cell sits discharged)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Limit to long-term storage of AGM batteries

    you are describing what cellphone towers do except they don't wait to see if and when they go bad for they get rid of them. i'm not sure how often they cycle their batteries as maybe somebody here may have an incling as to how often.
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #4
    Re: Limit to long-term storage of AGM batteries

    Don't know about East Penn (Deka and MK) batteries. Exide claims "20 years design life in float applications at 25°C (77°F)" for their Absolyte AGM batteries.

    See: http://industrialenergy.exide.com/products/range_select.asp?range=GP&sub_id=17&lng=en&cl=np_brands

    HTH,
    Jim / crewzer
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  • LBergman
    LBergman Solar Expert Posts: 42 ✭
    #5
    Re: Limit to long-term storage of AGM batteries

    Thanks for the replies everyone. Just wanted to ping the folks here to see if anyone had any thoughts or information, nothing serious. Seems encouraging though that the lifespan in such a situation appears to be 20 years for at least one brand's product line.

    One other thing I've been curious about is flooded batteries which come dry (electrolyte gets added later). Would I be too off base by saying the life span of those types is indefinite? The lead plates I assume would oxidize over time and ruin the battery, but assuming the battery was designed such the plates could be removed easily, one could remove the oxidation (light sanding, chemicals, etc) and restore the plates to like-new status before activating it.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #6
    Re: Limit to long-term storage of AGM batteries
    LBergman wrote: »
    , one could remove the oxidation (light sanding, chemicals, etc) and restore the plates to like-new status before activating it.

    mmmmm ---- sanding lead. Can I have a side of asbestos with that , to go ?


    I've never seen a dry battery that you could open. They all seem to be sealed, except for the caps.

    They are also "dry charged", meaning the battery is built, charged, and then drained. So there is some sort of structure of the lead, it's not just "fresh cast".
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • LBergman
    LBergman Solar Expert Posts: 42 ✭
    #7
    Re: Limit to long-term storage of AGM batteries
    mike90045 wrote: »
    mmmmm ---- sanding lead. Can I have a side of asbestos with that , to go ?


    I've never seen a dry battery that you could open. They all seem to be sealed, except for the caps.

    They are also "dry charged", meaning the battery is built, charged, and then drained. So there is some sort of structure of the lead, it's not just "fresh cast".

    Yep, sanding lead isn't too good, but if you wear gloves and a respirator... ;) (OK, don't seriously sand lead no matter what.)

    Anyway, the idea is to remove whatever detrimental layer forms on the lead over a long period of time, maybe by some chemical means. I'm also sure a flooded lead-acid battery could be designed so the plates can be lifted out & replaced or serviced. (Or can't it?) If you have to remove the outer layer on the plates, I'll guess there would be a way for the end user to reform (or "charge") them by following a process.
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  • adas
    adas Solar Expert Posts: 136 ✭✭✭✭✭
    #8
    Re: Limit to long-term storage of AGM batteries

    Aloha, the quick answer is that there is more to just the surface of the lead that gets contaminated. I read (I probably have the wrong terms, but here a shot) >>>> there are secondary and even deeper contamination of the lead plates, not just the surface, which may be cleaned easily and the penetrated contamination may not.
    frank
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