AGM vs Others

boisblancboy
boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
I have done alot of reading on the different types of batteries and the pros and cons of them all. With AGM batteries I am assuming the biggest con to them would be that you cant do simple maintenance on them being sealed. From you guys that have personal experience with these batteries could you give me your pros and cons to them vs other types of batteries?
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Comments

  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: AGM vs Others

    I'm not sure how a battery can have a "con" that doesn't need to be fiddled with

    Flooded are a complete pain in the rear ... need constant and vigilant monitoring and have much higher self discharge and lower charge efficiency compared to AGM

    I have had both, I'll never buy flooded again and I'm completely happy with AGM's I now have.

    The only "con" is AGM has a higher upfront cost, but when one considers the huge loss flooded battery's have efficiency wise and compare that to the cost of additional PV need with flooded that isn't needed with AGM, AGM is actually a lower cost solution on net watts delivered
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: AGM vs Others

    I just wasn't sure because i read alot where people with large battery banks and such do lots of routine maintenance like adding water, checking gravity, stuff like that. Is that more of a personal preference to have those types along with a necessity?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: AGM vs Others

    The "cons" to AGM are they are about 2-3x as expensive and easier to ruin if you over charge them (they vent gas/electrolyte and there is no way to refill them).

    Otherwise, they are a much better battery (many can take higher charging currents than a standard flooded cell lead acid battery).

    Many times though--we will recommend that you get a cheap flooded cell battery first. As most people (including yours truly) will kill their first set or two of batteries (over/under charging, too much load, load left on until battery is dead, etc.) and it makes sense to get a set of "training batteries" first.

    When you get to the larger batteries (fork lift size)--you might not find AGM batteries available.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: AGM vs Others

    I can see discharging the battery to far would be my problem until learning how to correctly not to discharge to far without having an expensive battery monitor. Now overcharging shouldnt be much of a problem since the CC would take the human error out, of course if you are using at CC.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: AGM vs Others

    A battery monitor is your best investment dollar! A couple hundred spend on one will pay off in battery life,,, plus it is kind of fun to watch the numbers roll up or down.

    As for CC taking the human element out,, assuming it is a quality controller, has temp comp, and is adjusted properly. Also you do have to monitor water, eq sometimes etc.

    Tony
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: AGM vs Others

    The Watt's UP and Doc Wattson meters may be worth looking (less than 1/2 the price) at if you cannot justify the Trimetric Battery Monitor.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: AGM vs Others

    Currently I have the ProStar 30m(has the digital meter) and actually just today recieved, from our hosts website, a RTBS that I will install tonight some time.

    Once I am doing more than just charging one battery here and there and actually have a battery bank of some sort I will for sure get some kind of Battery Monitor.
  • System2
    System2 Posts: 6,290 admin
    Re: AGM vs Others

    I am really happy with my set of AGM batteries. I did not follow the advice of many here and start with a set of training batteries. I built my system from the start with AGM batteries. They are now almost two years old and doing great. As others have said, they do require special care when charging to prevent overcharging. Fortunately my MX60 is easily programmed to correctly charge AGM batteries. Likewise, my Magnum inverter was easily programmed to charge from my generator. I regretted not buying a battery monitor when I first set up my system since this is best way to know the state of charge of an AGM battery. I added one this year and feel much more comfortable knowing the actual battery state of charge.

    In addition, my system is left unattended for a couple of months in the winter in the Colorado mountains. The AGM batteries provide better freeze protection than flooded batteries. This combined with not having to add water and mess with flooded batteries drove my decision.
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: AGM vs Others

    I also have gone through the open wet cells and now am in to AGM's. Regular wet cells are much more forgiving. Even my new Trojan 105's were about 93% efficient, change in to charge out and when I replace them they were about 85%. I also had to occasionally EQ charge them, which was a total throw out of power, I don’t need to do this with the AGM’s.

    With the AGMs I have, now three years old, I finally gave in and dropped their efficiency to 97%, it's really about 97.5% but I would rather error on the low side. When they were new, they were at about 98.5%. No water, no mess, dry clean, I will never go back.

    I would agree, buy regular cells first and if you can get them to last 5+ years, then switch to AGM's. And get a good battery monitor, it's one of the best things you can do for a battery bank.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • boisblancboy
    boisblancboy Solar Expert Posts: 131 ✭✭✭✭✭
    Re: AGM vs Others

    Thanks for all the replies everyone. Sounds like the AGM's are a favorite. But for sure i will get a Battery Monitor once I graduate to a battery bank. Besides for charging one battery here and there all i will be doing is running one besides lamp for now.
  • hillbilly
    hillbilly Solar Expert Posts: 334 ✭✭
    Re: AGM vs Others

    You did ask for opinions from those who have experience with AGM's which I do not, but I will throw my $.02 in anyways, since no one else is saying it. I too like the idea of using AMG batteries, but there are two big cons for me: much higher cost, and a warranty that is much lower. That is always a hard one for me to swallow, regardless of the product. I am willing to pay a bit more for a product that the manufacturer will stand behind with a more robust warranty, but to pay more for something that the manufacturer is not confident enough to issue a competitive warranty is hard to justify.
    I am sure that this is somewhat skewed do to the very real possibility that the user will ruin any battery by abuse/neglect. AGM's are known to be a bit more sensitive in this regard, but still looking at the warranties there is a huge difference: 1 year (concord), 3 year (Deka), VS 7 - 10 years for Trojan, Surrette, Crown etc...
    I suppose it depends a lot on how big of a battery bank you are looking at, if it's a smallish 12V bank, not such a big deal. But if one was building a large 48V system... I think that's a lot of $$$ to put into something that is sensitive with only a 1-3 year warranty.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: AGM vs Others

    I really think you have to look carefully at life cycle cost. Figure your draw down/recharge rate, the percentage of each, the number of cycles that you could expect with those numbers for each battery size and type, and then compare them with the others.

    I made the calculation that given the cost difference between L16's and T105 flooded batteries, with respect to their size and my expected use pattern, I figured that the T105's win if they last 6 years against the L-16's lasting 10. (I don't remember the exact numbers, but you get the point)

    Add in an Idiocy factor of some sort, and that will help you get your answer. I have gotten 10+ years from L-16's. I have also gotten 10+ years out of t-105's so take your best guess!

    Tony
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: AGM vs Others

    I had wondered about Gel vs. AGM.

    At least for the Deka batteries, the Gel seems to outlast the AGM version by a wide margin. Is this just wishful thinking, optimal testing, or something else?
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: AGM vs Others

    sub3mm,
    where did you see that for their gels and give a link please?
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: AGM vs Others

    It took a few days of not being able to sign in to post, but finally I can.

    First, the Deka 8g8d gel battery cycles: http://isaveenergy.com/productimages/batteries/deka/manuals/8G8D.pdf
    (6000 cycles at 10%)

    Second, the Deka 8a8d AGM battery cycles:
    http://isaveenergy.com/productimages/batteries/deka/manuals/8A4D.pdf
    (3200 cycles at 10%)

    Finally, the Rolls batteries (both the 5000 series and the 4000 series):
    http://rollsbatteryne.com/rolls_%20marine.htm

    So are the claims realistic for what people who have them observe?
  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: AGM vs Others

    I question the figures for the gel battery, as they are typically about the same as for an AGM or flooded battery with the same chemistry.

    The problem with gelled is seldom the cycle life of the plates, it is that problems with the gel itself can occur if overcharged even a single time. Gelled are a lot more picky about charging voltages and charge rates than AGM and flooded.

    And in our experience with gelled in hot climates has not been good, which is why we stopped selling them a few years ago.
  • Malasombra
    Malasombra Solar Expert Posts: 24
    Re: AGM vs Others

    In a AGM how is the electrolyte? liquid like flooded models , gel ,or depends on SOC:confused:
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: AGM vs Others

    I know I was concerned about the lower listed life cycle. Mine have been in service for just over three years (is that right Jim? I got mine just after you did). I tried switching them to 97% (in to out) recently, but I switched it back to 98% because it was closer every time. I run about 20% down once a day since I have had them. Only time will really tell but so far so good.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: AGM vs Others

    http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf See section 1.2

    Basically AGM are spun glass mats soaked with acid with no free liquid.
  • Tuner
    Tuner Registered Users Posts: 7
    Re: AGM vs Others

    FWIW, I run two 8D AGMs in my boat, one as a starting battery/backup and one as the house source.

    The boat was built in 1990. I ran flooded 8Ds from Sams until four years ago and usually got 3-5 years service life. They were a bear(cleaned up by niel, kids may be present) to remove to check/add water. The AGMs have been flawless, hoping to get 8-10 years from them and have not had to wrestle them around for watering.
    agm.jpg 24.1K
  • Malasombra
    Malasombra Solar Expert Posts: 24
    Re: AGM vs Others
    Windsun wrote: »
    http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf See section 1.2

    Basically AGM are spun glass mats soaked with acid with no free liquid.

    Thank you, very clarifying.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: AGM vs Others

    Brock,

    Yeah.. 3+ years! Mine are now 3-1/2 years old, and, so far, so good...

    Regartds,
    Jim / crewzer
  • Bob McGovern
    Bob McGovern Solar Expert Posts: 25
    Re: AGM vs Others

    AGMs are great. Sort of like DVDs -- hardly the last word in the technology, you can see the next gen of storage media that will replace them on the horizon, but way better than cassette tapes, and here now. AGMs are kewl.

    That said... good, high-capacity, true deep-cycle AGMs cost big bucks. I worry people unavoidably undersize their battery banks due to the cost, and that has negative consequences. The batteries work too hard, and die young. And there's a feedback loop, where big batts act bigger than they are and small ones act smaller, because of hour-rate issues. A battery discharged over 20 hours will deliver nearly twice as many Amps as the same batt discharged in eight hours. You can leverage capacity by sizing your batteries so you have something like 100 hrs of expected power use. But can you afford that with AGMs?

    I couldn't; even though we consume overall very little power, my woodworking business uses amps in sizable blocks (I ran a planer/dust collector for 4 straight hours yesterday.) Accounting for those sustained draws would require $10k in AGMs.

    A better option for me was flooded lead calcium, aka telecom batteries. These do not suffer the same self-discharge or water-loss problems as lead antimony batteries. In fact, their self-discharge rates are similar to AGMs (1% per month), and mine have never lost a mm of water in over five years. They can be had for 1/3 the cost of AGMs, and they are very robust if treated well and absurdly oversized.

    Downsides: they are bulky and heavy for their capacity (lower power density than AGM). They must be racked upright. They do not like repeated deep discharging and must be sized to keep you in the upper 50%, preferably in the top 20%. They are (comparatively) sluggish accepting and releasing amps, tho if properly oversized that isn't an issue. Chances are you would be purchasing used telecom units, and it's hard to know how they were treated and how much life they have left.

    Tradeoffs, tradeoffs. If buying new and I had the money, I'd get quality AGMs in a heartbeat. Still can't beat flooded batts for dollars per amp, tho, if you understand and accept their limitations. I have ~10,000 Ah @ 24V installed capacity, and they cost $3200 delivered.
  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    Re: AGM vs Others
    I have ~10,000 Ah @ 24V installed capacity, and they cost $3200 delivered.

    You just made me cry, I got 440 AH for $ 1600.00 in Optima yellow top AGM batteries.
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: AGM vs Others

    First, many of those who like AGM's are On-Grid, which is not a cyclic use (in general). Flooded batteries make much more sense for Off-Grid, cyclic use.

    AGM do not permit measuring the specific gravity of each cell. This is important in determining real depth of discharge, and adequacy of charge. AND, AGM's need not be Equilized, and CANNOT be EQed. EQing can correct charge divergance of cells. This is especailly important when cycling batteries daily.

    When specifying flooded batteries, it is very good to try to use a single string if possible -- this minimizes the number of cells to monitor, S.G., and fill. Also elimnates the enevitable differences in strings. For multiple strings of AGM's, have read that periodically one needs to fully charge them, take them off charge for 6-24 hours, disconnect each string, measure each battery's voltage, and try to rearrange the batteries into strings as close-to-dentical as possible. This also sounds like a joy to me !

    I believe that follded batteries are more rugged, and forgiving vs AGM's.

    But for Float service, AGM are very nice. Really depends how one will use their batteries. Ignoring any battery is a very bad idea.

    We each look at the world a bit differently. Good Luck. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • Bob McGovern
    Bob McGovern Solar Expert Posts: 25
    Re: AGM vs Others
    n3qik wrote: »
    You just made me cry, I got 440 AH for $ 1600.00 in Optima yellow top AGM batteries.

    I occasionally have this nightmare where my batteries die and I have to get them back out of the cellar. Then it's my turn to weep. :cry: Here ya go -- pop can is for scale:

    batts.jpg

    When the day comes, it may be easier to backfill the cellar with baking soda and dig a new one.:D

    But here's the thing -- the batts sit now at 24.3 V, 97% full by the Trimetric (meaning 99%, really), and I just got done milling, sanding, and spraying 200 lineal feet of hickory baseboard. It's like we're not even here.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: AGM vs Others

    Need to rig up a davit and a scuttle hole to raise and lower them with.

    I had a set of L-16's that had to come down the lake in a skiff, hand lifted out onto the dock,,,then carried through the rough bush for ~100' into the power house! Same in reverse as they have failed.

    The T-105 are easy by comparison.

    Tony
  • Bob McGovern
    Bob McGovern Solar Expert Posts: 25
    Re: AGM vs Others
    icarus wrote: »
    Need to rig up a davit and a scuttle hole to raise and lower them with.

    I had a set of L-16's that had to come down the lake in a skiff, hand lifted out onto the dock,,,then carried through the rough bush for ~100' into the power house! Same in reverse as they have failed.

    The T-105 are easy by comparison.

    Tony

    Ouch. L-16s are heavy brutes. And you faced the added danger of random moose attack!

    Believe it or not, I really am compulsive about certain things and designed into the house's floor plan a means of evacuating the batteries. A broom closet directly over them has a removable floor (30" square); above that is a 12"x6" steel I-beam (part of the house structure), ready for a chain hoist. Cuz trundling them up the stairs is not happening.:D
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: AGM vs Others

    Smart boy!

    I have rigged up a davit on my fuel shed dock. My days of hoisting 100# propane tanks out of the bobbing boat are limited. Also things like L-16's. Our problem is that once things are on land, the ground is so rough no such thing as a wheeled load. I try to move most stuff in the winter on a sleigh.

    T