Agm life expectancy?

backroadbackroad Solar Expert Posts: 185 ✭✭
My old system used 12 L16 Crown Batteries and I'm really considering on my new system of going with the AGM PVX-3050T Concorde's....in a 48 volt bank with two strings of 8 batteries each. What kind of life in good circumstances should I be looking at? Or should I be considering some of the industrial packs from Crown for longer life.
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Comments

  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: Agm life expectancy?

    I am curious as to how many folks out there have any AMG's that have been around for a while. They sure are nice and clean and all, but so far I have to say that the longevity factor seems a bit too much in question for me personally. It seems that AGM's would be great for very small systems, and small grid tied emergency back up applications. For an off grid full house system, I'd be a bit hesitant to sink that kind of $$$ into an AGM battery bank. The fact that you don't have a way of checking the condition of each cell is a bit worrisome, particularly with that many cells (and that many connection points) ... a lot of potential for things to go out of balance over the long haul. This is all just an opinion, my only personal experience with AMG's is a small one (34AH) that I use on road trips for device charging, and it's been great so far (1 year).
    Perhaps in a few more years we might start seeing more reporting on long term performance and longevity, so far I've not heard too many experiences more than a few years. Anyone out there using AGM's off grid have some personal experiences to share...???
  • trumpets3utrumpets3u Solar Expert Posts: 35 ✭✭✭
    Re: Agm life expectancy?

    We have 6 lifeline batteries [email protected] 770 AH. We added them as we could, I know that isn't good but oh well. 2 of them are 7 years old 5 and 2 years old We have not had any problems yet but at sometime down the road we will look at what is out there, things are changing quickly, we do need more.
    Brian
  • Solar GuppySolar Guppy Solar Expert Posts: 1,959 ✭✭✭
    Re: Agm life expectancy?

    AGM's are better battery's ... no question about it. What is a concern is they won't tolerate misuse the same way a wet cell would. So if your a user who doesn't know your loads, or runs things till the inverter shuts off due to low voltage, AGM is NOT for you.

    For any long term on or off grid solution, they are much better, the efficiency benefit alone is worth the price difference over wet cells, with wet cells, your looking at 20-30% charging losses ... in a true off-grid, ie your homestead, that's allot of energy you have to make to just bubble the electrolyte.
  • lamplightlamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
    Re: Agm life expectancy?

    I'm also interested in the off grid longevity of agms that are regularly drawn down (within normal tolerance) , not just used (as you commonly see them) as grid tie backup. Would like to hear other experiences too, long term (+ 5 yrs?).
    Thanks!
  • backroadbackroad Solar Expert Posts: 185 ✭✭
    Re: Agm life expectancy?

    I was just looking into the new Concorde AGM that has an AH rating of 305 @ 24hrs. I don't plan on abusing my next battery bank by running it down excessively. My first purchase is going to be a 12-15K Perkins Genset that will start up on its own before the batteries even think about complaining. The generater size is quite large for a normal solar system, but I've got a very large 5hp compressor, MIG welders and lots of abusive tools that I want to play with when I retire.

    I did contact Concorde and asked them why they didn't believe in their AGM batteries enough to put a decent warranty on them....So far no answer....And I'm like most of us and just not really wanting to take a chance on an iffy warranty and a possible lack of longevity. It's really not that bad to have to add a bit of water every so often. Still in the fact finding mode...
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    when treated right they can last a long time. mine is approaching 5yrs. they can't discern which were abused as easily with this type of battery is my guess as to why they don't warrant them longer. it isn't that the batteries fail early or often as much as it is their owners that do.
  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: Agm life expectancy?

    Well I am certainly NOT a battery expert here, but I am a fairly cautious one when it comes to shelling out big bucks. I can absolutely agree that AGM's have some very nice advantages, but I am a bit wary of dropping the big bucks for a large off grid battery bank. Regarding battery longevity and abuse, I'll say that I'm not so convinced that any batteries are totally foolproof.
    Personally I've been pretty good to my 8 surrette's, very light loads, shallow cycled, watered regularly, EQ'd regularly, etc... and yet still started to develop a bad cell. If all I had to go on was reading the voltage levels, and charge acceptance rates, I would not have had a clue, thankfully I caught it with a hydrometer before things got way out of hand. Had these been AGM's I would be totally unaware to this day, and would have only noticed once major sulfation had developed.
    My only point is that when you have a lot of batteries in series/parallel, there are ample opportunities for unequal charging/discharging, and I am just a bit uncomfortable with the idea that I would not be able to really know the health of each of the cells if something was going wrong. Perhaps if I had a small single string set up with minimal connection points, I would not be as concerned; but looking at two paralleled strings of 8 batteries each... thats a lot more cash, and a lot more potential for problems. Anyways, I still would be more curious to hear from any folks with larger banks of AGMs, using them in a full time off grid application (grid tied, small back up application, is a very different animal entirely).
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    hillbilly,
    nobody is trying to sell the agms on this thread, but only address their longevity. for the record, i really don't mind anybody having other types. do know that there are far too many agms out there that work and work quite well for you to so easily dismiss them. i don't believe cells going bad on standard batteries is an argument against agms and may be an arguement against standard batteries for i don't hear of cells going bad on agms like i do for standard batteries. purchasing agms is also a judgment call by the one making the purchase. there are pros and cons to both types, but the subject is agm longevity and again cells going bad on standard batteries has no bearing on the subject of agm longevity and you seem to be reaching too far here.
  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: Agm life expectancy?

    Neil, hope my posts didn't come off the wrong way. I don't mean to dismiss AGM's at all; I am actually very curious to hear more on them. Just voicing my *opinion* that it seems like they might be a bit of a gamble in terms of long term off grid applications. I thought it was relevant to the topic in question, no disrespect meant to AGM's or others opinions. I think that many of you here who own AGM's (particularly you, Guppy, and Crewzer) are far more educated in these manners than I, and I respect your knowledge greatly. There is often times a big difference though between conceptual knowledge and real world experiences... hence the line that I would love to hear more from people who have used these types of batteries in off grid systems for some time.
    Cheers
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    "There is often times a big difference though between conceptual knowledge and real world experiences... hence the line that I would love to hear more from people who have used these types of batteries in off grid systems for some time."

    you are the only one talking of a, or any, concept that bad cells in standard batteries constitute a fault in agms. i was not talking of any concepts here and i too would like to hear of any others that may have had them longterm. if this results in few to no responses i would not be surprised as their popularity among the general populace wasn't until recently so no analogy or conclusions can be drawn from a lack of responses as there's fewer of them from that far back. they did exist in military and aviation and were probably made to be better through their trials and tribulations, but i don't know of the lifespans that they had experienced.
  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: Agm life expectancy?

    "you are the only one talking of a, or any, concept that bad cells in standard batteries constitute a fault in agms."

    ???

    Sorry, I'm not sure quite how that came across from my post.... I only meant to point out one example of a "concern" about longevity of an AGM battery bank (meaning the lack of ability to check the specific gravity of the electrolyte).
    Regarding the "bad cell", it was apparently due in part to unequal charging/discharging; with larger numbers of batteries and connections the potential for this goes up (OP was about a bank of 16 batteries, so worth considering this issue). Due to the fact that I was able to check the specific gravity, I happened to notice that despite all other signs indicating that things were running smoothly, one cell was NOT getting it's full charge. Was able to EQ, and monitor all cells for a while and so far everything is back to normal (I have been checking the SG readings a lot more frequently since then).
    Again, I don't see AGM's as "faulty" in any way... but I do think that questioning their dependability over a long term service is wise. It also seems that the most of the folks who voice most strongly in favor of them are grid tied... pretty different application than a full house stand alone system.
  • backroadbackroad Solar Expert Posts: 185 ✭✭
    Re: Agm life expectancy?

    I agree wholeheartedly.....I do question the longevity of a large off grid bank.

    I did get hold of a very nice gal from Concorde yesterday. All she did was refer me to a graph involving depth of discharge and the battery cycle. It would be great if I only had to drop 10% on every cycle. It would mean that the battery was good for 5,000 cycles. But, alas, we don't live in the Utopia yet. Concorde was not about to give an estimate of battery life in years.

    I'm going to have to give NAWS a call and get their opinion, if'n they've got one.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    let me give it a try based on their chart. for 20% dod that would roughly be 2800 cycles. if you cycled once every day that is 2800/365=7.67yrs. at 50% dod it is roughly about 1000 cycles and divided by 365 = 2.74yrs. i think you can gauge some things from that. don't forget they are very efficiently charged too.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Agm life expectancy?

    I think I can paraphrase what HBilly is saying. He questions the long term cost/benefit of AGM's given the collective experience amongst (a small number to date) off grid users. His point,,(I think) is that, given the additional costs of AGMs, AND the fact that you can't check the SG of each cell, there may be an additional financial risk with AGMs.

    Even though the specs may call for X number of cycles and therefore Y years of service,,, the big question is what would the average failure rate be given a certain number of cells? Greater than or less than that of flooded cells? If those numbers can be determined THEN one can make a risk benefit analysis.

    Have I got it sorta right HB?

    Tony
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    ok. i can't say what that would be, but he might try phrasing it that way to the battery companies. battery failure rates would be something outside the norm of cycle life. they may not have that info either seeing as how they have a relatively short warranty. try as many battery manufacturers that have agms as you can to see if you can get an answer. i'd be interested too.
  • QuabillionQuabillion Registered Users Posts: 22
    Re: Agm life expectancy?

    Well shoot, looks like I have alot of typing to do here ;)

    As yall see in my sig I have an AGM bank and have been off grid since June of 03.
    So maybe I can answer some of these questions yall have.

    My batteries are Werker brand and were purchased at Batteries Plus in Austin Texas. The cost was $139 each and I bought 6 of them. They are rated at 12v 100Ah for a bank total of 600Ah.

    I have never had a bad or shorted cell in this bank to date.

    I chose AGM because of my mounting location, under my dinette bench inside the RV living area. I have seen zero corrosion of the terminals and zero corrosion anywhere near the batteries. So no leaks or spills to report to date.

    According to my link10 my deepest discharge was -255Ah, average 89Ah.

    The bank has been in constant use, as I live in my RV traveling around the country. The primary duty is keeping my fridge cold, and the fridge is what takes the lions share of my power, about 45Ah a day.

    The lowest I have ever seen the voltage was 12.2. This was in the morning while I microwaved a breakfast biscuit. The load from the microwave is 135A, via the inverter.

    I am not claiming to be any battery expert here, but I am very happy with my AGMs and have had no problems at all. The only maintenance that has been needed is tightening the terminals every 6 months.

    Anything I didnt cover here, please feel free to ask and Ill do my best to answer any more questions.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    did your werkers have a warranty and for how long? what would you say you draw down from your batteries overall on average so that we may get a better idea of the dod %?
  • QuabillionQuabillion Registered Users Posts: 22
    Re: Agm life expectancy?

    Warranty?? Hrm. I dont know for sure. I havent ever inquired about that.
    I am sure it is some store warranty policy, not a mfg warranty.

    My link10 displays my DOD as % charged, (100%= fully charged)
    My average % at bedtime is about 65% charged IIRC.
    In the morning it might be 60% just before the solar kicks in.


    I have noticed the bank is not staying above 13.0 during the evening, it is sagging down to 12.7-.8, where when they were new the voltage NEVER went below 13.0.
    Showing their age I suppose.

    I plan to keep them until they start sagging down to 12.0 - 11.8 range each night, then replace them.

    I guesstimate this bank will be in use for another 2-2.5 years, then replaced with the same AGM brand/style.

    I am unsure what I will do with the old bank, perhaps use them as test equipment, or see just how high the voltage can be raised before outgassing occurs. I dunno, it will be fun though.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Agm life expectancy?

    staying at 13v or higher? that may not be normal(seems too high), but i don't know what your agm's charge parameters should be or what you are charging them with, as in charge controller (bts, yes/no?). i looked at their website and don't see anything over about 50ah so do they still carry your model?
    i think it's premature to say they need replaced yet. a load test could indicate their condition better. what do you have set for the acceptance and float voltages and if the cc can do it do you eq charge at all and at what voltage setting?
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Agm life expectancy?

    My 2 kwhs worth,,, and I'm not sure if it makes sense or not,,,

    It seems that your battery bank is a bit too small if you are routinely drawing it down ~45% each day. I personally prefer to only draw down 20% max.

    It also looks like your 1.4 kw of panel capacity would put out ~20% of the ah capacity of the battery, something in the neighbourhood of 100amps. (I am assuming 12 volts here) 100 amps into a 600 ah battery is better than 15%,, above the recommended 5-13% extolled here and there on this site.

    I suspect that you have size constraints for mounting more batteries,, but if it were me,, I would try to add at least two more batteries in my next string. On the other hand if you get better than 5 years out of your existing bank you must be doing something right.

    Tony
  • QuabillionQuabillion Registered Users Posts: 22
    Re: Agm life expectancy?
    niel wrote: »
    staying at 13v or higher? that may not be normal(seems too high), but i don't know what your agm's charge parameters should be or what you are charging them with, as in charge controller (bts, yes/no?). I have 2 xantrex c40 charge controllers currently,both with BTS, soon to be upgraded to a flex max 80i looked at their website and don't see anything over about 50ah so do they still carry your model?In the store yes they do. I was in Austin just a few weeks ago and saw my model still on the showroom floor.
    i think it's premature to say they need replaced yet. a load test could indicate their condition better. what do you have set for the acceptance and float voltages Bulk is 14.2 Absorption is 13.8 float is also 13.8and if the cc can do it do you eq charge at all and at what voltage setting?I have NEVER EQ these batteries

    The charge controllers are my weak link in my system, I am embarrassed to admit I use that PWM stuff.
  • QuabillionQuabillion Registered Users Posts: 22
    Re: Agm life expectancy?
    icarus wrote: »
    My 2 kwhs worth,,, and I'm not sure if it makes sense or not,,,

    It seems that your battery bank is a bit too small if you are routinely drawing it down ~45% each day. I personally prefer to only draw down 20% max. I agree, I am being hard on the bank, wish it was larger.

    It also looks like your 1.4 kw of panel capacity would put out ~20% of the ah capacity of the battery, something in the neighbourhood of 100amps. (I am assuming 12 volts here) 100 amps into a 600 ah battery is better than 15%,, above the recommended 5-13% extolled here and there on this site.The highest charging current I have ever archived is 67 amps. My panels are mounted flat without tilt ability

    I suspect that you have size constraints for mounting more batteries,,Yup, only 6 would fit, as well as weight being an issue. but if it were me,, I would try to add at least two more batteries in my next string. On the other hand if you get better than 5 years out of your existing bank you must be doing something right.

    Tony

    I try to be a gentle as practical with my bank, but alas, I will fall asleep with something on from time to time, mostly the TV and DVD player or sat box. Heck one time I came home drunk from a party and passed out with ALL of the lights on:blush: whoops. It didnt seem to have an immediate affect, but I am sure such abuse will shorten lifespan.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Agm life expectancy?

    So if you have been off grid since '03,, are you still on the original batteries? If so,, with the usage pattern you describe I think you are doing pretty well. That is something like 2500 cycles to 65% soc. Not too bad. The concorde site suggests that at 40% dod, one should expect ~1500 cycles. (20% dod should yield upwards of 3000 cycles,,, 5000 at 10%).

    Tony
  • QuabillionQuabillion Registered Users Posts: 22
    Re: Agm life expectancy?

    Yes they are my original batteries, installed 5-03.
    They are my "learner" batteris, ie; first set.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Agm life expectancy?

    Like I said,,, a pretty good record. I'll have to look into your "werker" batteries, seems that they are made by Exide.

    T
  • QuabillionQuabillion Registered Users Posts: 22
    Re: Agm life expectancy?

    I did some looking at batteries plus website and it seems niel is correct, my model is not shown. My exact model number is WKA12-100J/FR. Searching for this model number comes up with some other brand, Power Sonic, in a different style case and color. Odd. But upon closer inspection I see that my model is carried "in store".

    Dont know why its in the store but not on the website.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: Agm life expectancy?

    Manufacturers will often sell batteries under a number of brand names. There are only a limited number of manufacturers. I suspect that your brand/model/specs come from a different manufacturer.

    Tony
  • backroadbackroad Solar Expert Posts: 185 ✭✭
    Re: Agm life expectancy?

    Hummm...Very interesting....I suppose that I could always set the generator to kick on before they discharge to 80 or 85%.....Would I spend more in fuel than I'd save in battery life?
  • backroadbackroad Solar Expert Posts: 185 ✭✭
    Re: Agm life expectancy?

    I was just sitting here, running some figures on the scratch pad (can't afford a calculator:):):)

    My previous bank was a 24 volt system. 12-L16 Crown Batteries @ 395ea @ 20 hrs.

    I want to step up on the reserve a bit...

    ? going to a 48 volt system.
    16-L16 crowns $4480 16-305ah AGMS $5286
    24-L16 crowns $6720 24-305ah AGMS $8064

    The AGM's of course would be a little bit of a step down in output from the L16's. 8)
  • backroadbackroad Solar Expert Posts: 185 ✭✭
    Re: Agm life expectancy?

    STILL SCRATCH'n

    8 of the Surrette 6 volters @ 546ah $6880

    16 of the Surretter 6 volters @ 546ah $10,320


    OUCH..............
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