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AGM Battery questions...

Discussion in 'Photovoltaics' started by Don Oldfield, Mar 8, 2005.

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  1. Don Oldfield

    Don Oldfield Guest

    I just read with interest all those flaming remarks about AGM batteries. In
    my area (North Florida), I can purchase Optima AGM batteries (Navy Exhange)
    or similar looking AGM batteries from SAMs club. My thoughts were that
    these would not only work as automotive batteries, but also could be removed
    (if needed) and used with photovoltaic panels without the consequences of
    spilling battery acid... Particularly for hurricane preparedness (would
    probably have to charge with motorized charger - not much sun in hurricane
    conditions). So, here are some questions: What kind of life expectancy
    would I get from such a battery used in a small gas guzzler automobile; that
    is, would the battery have the same or greater life expectancy in automotive
    use than that of a good quality lead acid battery? Would the extreme marine
    use battery work in an automotive application? Do AGM batteries offer a
    greater depth of discharge than standard lead - acid batteries? Thanks for
    your help!!

    Don in sunny Florida
  2. Steve Spence

    Steve Spence Guest

  3. Windsun

    Windsun Guest

    The Optima are not deep cycle batteries, so I would not really plan on using
    them in a solar system unless nothing else was available. AGM does not equal
    deep cycle.
  4. George  Ghio

    George Ghio Guest

    And may not suit you purpose.
  5. Steve Spence

    Steve Spence Guest

  6. daestrom

    daestrom Guest

    Could you explain a little more detail as to why they 'may not suit you[r]
    purpose'? Something a little more than a link to a web site that says
    'generally not suitable'.

    Do they self-discharge more?? (no)
    Do they not accept as high a charging current?? (no)
    Do they use more water and require more maintenance?? (no)

    Just *why* do you feel they are not suitable?

  7. George  Ghio

    George Ghio Guest

    Oh I sell them. I have used them.

    They still are not generally suited to solar.

    Which is the point.
  8. Windsun

    Windsun Guest

    Well George, I just had our sales department check our total sales
    (including all of our installations) of all AGM batteries since Jan 1999,
    and the total is over 62,000 batteries.

    Of those, about 95% were for solar systems, the rest for such things as UPS.

    Of those 62,000 "non suitable" batteries, we have had one single warranty
    claim, for a single 34 AH battery. And according to the notes on that one
    "it may have been frozen for several weeks".

    During that same period, we sold about 14,000 Trojan flooded batteries. I
    show 9 warranty claims. Since June of 2000 sold around 13,000 Surrette
    batteries, 8 warranty claims.
  9. ptaylor

    ptaylor Guest

    I assume all Optima brand batteries are AGM,due to thier spiral cell setup?
    I decided to opt for one when my last battery failed..I got the smaller
    "red-top" (55AH I think?) because they were out of the larger ones all
    over town..
    The cost was about twice what a normal batt would have cost,but so far
    I'm glad I did it. Cranks my old V-8 right over every time without a
    hesitation,even if I leave the lights on for a while,or use the inverter
    to run a soldering gun (120/230W hi/lo I think,with a 300W
    inverter.),etc.. (Had to do some wiring on the heater controls.)
    I even used the inverter once with it when the power went out.. didn't
    seem to care much..started the car right back up..I made sure it got a
    decent charge driving around the next day. ;-)

    Say,this may be a little OT,But you guys seem o know alot about this stuff..
    Does anyone here know of a good voltage regulator circuit for an older
    GM/Chevy ('67 Chevelle)?
    I bought a Solid State one for like $60 a while back,and the POS fried
    like 5 months later..(part of the reason my old battery died!) I took it
    apart to see.. *surface mount components!*
    No wonder!,it's amazing it held up that long!
    Sure a field winding doesn't need much current,but a tiny SMD transistor
    is not gonna cut it.
    I'm now using the old mechanical regulator,it works but has the typical
    "lights dim at idle" and slight "flickering" when the regulator is
    switching,and doing it's regulating thing..
    Kinda minor,but it bugs me! The Solid State one did none of that,And I
    liked it,untill it died..
    I've got plenty of parts around,and I can sling solder pretty well..
    I just need a circuit.. I suppose I could look at the wiring diagrams
    and figure it all out,but..uhm.. I'm lazy! LOL.

    TIA! Patrick..
  10. George  Ghio

    George Ghio Guest

    Sorry but selling them does not make them any more suitable.
  11. George  Ghio

    George Ghio Guest

    So let's say you have a system in an area that has 5 PSH(Peak Sun Hours)
    and 1020 Ah of Concord GPL-8DL batteries with a load of 10 kWh over
    night. Inverter efficiency 90%. Battery Efficiency 95%. How many panels
    are required to replace that 10 kWh load in the five hours?
    Assume a 12V system so you dont need to run a series/parallel battery
    set.(For simplicitys sake)

    You don't know.

    It ends here unless you can answer.

    As with Wayne, I ASKED FIRST.
  12. George  Ghio

    George Ghio Guest

    Thank you.

    It really is hard to understand the sad state of the education system in
    the US.

    The "usual suspects" went berko at the quote that AGM batteries are not
    generally suited to solar. This was part of a quote I used to explain
    why Steve could keep AGM batteries under his bed.

    The main reason why AGM batteries are not generally suitable for solar
    is that the bulk of the AGM batteries manufactured are not Deep Cycle or
    designed for solar.

    This fact is not my fault.

    But the "usual suspects" felt that they had a chance to score a point or
    two. Instead Windsun has shown his inability to size a simple system,
    Steve has exhibited an unhealthy emotional attachment to his AGMs and
    Wayne who can't define two days autonomy also tried.

    All on the simple fact that even if thirty percent (which is generous)
    of AGM batteries were made just for solar this would still be a long
    ways from "Generally Suited".

    Concord make some very fine AGM batteries in useful Ah ratings that are
    designed for solar applications.

    But the fact remains that the quote is true.

    The main reason I don't like AGM batteries is because they are to easy
    to destroy by people who do not understand what they are doing.

    Now if you look at Steves little rant above you will see;
    Require? Are you kidding?

    If you choose to use AGM batteries you had better make sure that they
    don't vent. When they vent, material is lost that should have been
    recombined within the battery. Once vented you can not put it back. The
    battery has lost capacity. Vent your AGM batteries a few times and they
    will fail prematurely. Another point for unsuitabilty, maintenance free
    has a down side as well.

    Steve has shown his ignorance once again. Just no hope for some people.

  13. wmbjk

    wmbjk Guest

    Since you came from here, you're living proof. Although I doubt the
    education system taught you pigheadedness. I expect that's something
    that a battalion of teachers couldn't cure you of.
    No, you made a number of *wrong* statements, and several people who
    know better corrected you. Once Windsun described 1400 successful AGM
    equipped systems, the smart move on your part would have been to say -
    "OK, I guess I don't know as much about AGMs as I thought I did".
    The bulk of flooded batteries manufactured probably aren't deep cycle
    or designed for solar. Would you say that flooded batteries are
    therefore "not generally suited to solar"?
    And yet they're a good choice when it's suspected that their owners
    won't attend to maintenance.
    Very creative. So the downside of not requiring venting or maintenance
    is that if you drill a hole in sealed batteries, the capacity will
    leak out?

  14. Steve Spence

    Steve Spence Guest

  15. Steve Spence

    Steve Spence Guest

  16. Landline

    Landline Guest

    George time you moved away from Concord to some quality Fullriver batteries
  17. daestrom

    daestrom Guest

    This seems like a poor argument for such a statement. The 'bulk' of flooded
    wet cells are not Deep Cycle or designed for solar either. Yet it is clear
    that some flooded wet cell batteries are quite well suited for such use.
    Just as a deep cycle AGM would seem well suited for such application.

    Suffice to say, that many types of AGM batteries are not well suited, but
    neither are many types of other batteries. Before buying any battery it is
    always wise to check the particular design against the application's

  18. Gymn Bob

    Gymn Bob Guest

    It has been stated that flooded cell batteries are not good for solar
    because of the maintenance current required to maintain them. This statement
    implies inefficiencies and one could conclude they are not good for any
    "green" application then but it is not totally true and no battery is
    perfect for anything, just more or less.

    It's definitely a science and an art, picking batteries.
  19. George  Ghio

    George Ghio Guest

    The notes quoted are becoming dated to be sure. Many of the problems
    that affected AGM batteries in solar applications can be solved with
    newer technology.

    Still as you say when one designs a system it is best to know what
    different batteries require in the way of maintenance.

    AGM batteries are not, as often advertised, "maintenance free"

  20. Gymn Bob

    Gymn Bob Guest

    Either is WindySOB...LOL
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