Any hope for these batteries?

tvengineer
tvengineer Solar Expert Posts: 31 ✭
in Off Grid Solar & Battery Systems #1
I was able to score some used UPS batteries today. They are in 4 years old and come out of a LARGE UPS system.

They are gell "data safe" batteries and are rated at 70ah 12volts. each.

The thing is.. they were part of a series string of 36 12 volt batteries... (yes.. nearly 500 volts) that was one of 2 series strings.. (72 batteries total)

When the UPS was installed .. the batteries were put into service (four years ago).. and were kept fully charged..
At some point in time, one of the batteries in the string suffered a catastrophic event (mechanically failed) and opened the circuit. So, from that point on the remaining batteries (35 of them) were sitting essentially disconnected and not being kept charged. No one knows when this happened.. could have been right after they were installed.. could have been last month..

At any rate.. most of the batteries in the string had very low voltage readings.. some as low as 7 volts.. I got the four with the highest readings.. all of mine currently read over 12 volts.

Questions.. what is the best way to rehabilitate them..
I am assuming a slow charge back up to their float voltage then maybe an equalizing charge...

Or .. is it even worth trying??

Louis
· Share on Twitter

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Any hope for these batteries?

    I hope you didn't pay anything for them.:blush:

    You do not equalize gel batteries or AGMs. You can charge them gently, let them sit for 24 hours, and see how the Voltage holds. But there's nothing else you can do with a gel cell. No way to check SG, desulphators are useless against gelled electrolyte, and you can't add any battery restoratives :roll: either.

    You probably will have difficulty disposing of them too, as scrap yards don't want anything by FLA's it seems.
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Any hope for these batteries?

    go for it if they weren't that low in voltage. try not to feed them too much current like a fla or even an agm might take by keeping the charge rate about 5-10% of the ah capacity. the 5%, or 20hr rate, is very common, but it can be 10% (10hr rate) too. when you've charged them up they should be load tested and gels dislike high discharges so this should be the same 5-10% discharge rate until 10.5v is reached and determine the time in hours it took to reach that point. for example a 100ah battery should dissipate 5a for 20 hours before hitting 10.5v. this could also roughly be 10a for 10hr, but it will be shy of the 10hrs to 10.5v making the 20hr rate easier to do being most batteries are rated for their 20hr rate. upon test completion immediate recharge is necessary as load testing is very stressful and a potential killer of weakened batteries.
    · Share on Twitter
  • tvengineer
    tvengineer Solar Expert Posts: 31 ✭
    #4
    Re: Any hope for these batteries?

    One thing..

    I put in my original post "GEL' battery.. they may well be AGM...

    dont know if that makes a difference...

    off to go look them up again to find out..


    Louis

    EDIT:

    They are Eneysys HX-300FR batteries...

    here is the specs for the HX300 (non FR)

    http://www.batteryuniverse.com/Sealed-Lead-Acid/EnerSys-Datasafe/HX300/HX300_EnerSys-Datasafe_HX300_Sealed-Lead-Acid-Battery


    Site just says "sealed lead acid" .. so I don't know if that means AGM or not.


    Edit again....


    They are AGM...

    :-)
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Any hope for these batteries?

    agms are more rugged, but you can still follow the 5-10% charge rate just to be sure as it won't hurt an agm in that range. discharge is the same for the load test as i prescribed in my previous post. i don't believe either gel or agm will have need of any charge voltages above about 14.4v. fla types may need higher, but by your comments it most likely isn't the fla type.

    edit to add:
    from your post you made while i posted i looked for further info on these batteries and they are agm.
    http://www.digikey.com/Web%20Export/Supplier%20Content/Enersys_842/PDF/Enersys_HX_RangeSummary.pdf
    do note that there are specific discharge specs given so you can test them. you can charge them at high rates, but they need to be kept lower than a specific voltage point set for switching out of bulk as agms are not to outgas or damage to the batteries can occur.
    · Share on Twitter
  • tvengineer
    tvengineer Solar Expert Posts: 31 ✭
    #6
    Re: Any hope for these batteries?
    Cariboocoot wrote: »
    I hope you didn't pay anything for them.:blush:

    Not a dime 8)
    Cariboocoot wrote: »

    You do not equalize gel batteries or AGMs.

    You probably will have difficulty disposing of them too, as scrap yards don't want anything by FLA's it seems.


    So.. they are AGM's .. does that make a difference?

    As for disposal.. I am sure I can handle that for 4 batteries :roll:
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
    Re: Any hope for these batteries?
    tvengineer wrote: »
    Not a dime 8)



    So.. they are AGM's .. does that make a difference?

    As for disposal.. I am sure I can handle that for 4 batteries :roll:

    Charge-wise, it's just like Niel says; both gels and AGMs prefer lower Voltage and current than FLAs. (correction from niel-agms do like and can take higher currents, but are sensitive to excess voltages causing the safety vents to outgas losing water that cannot be replaced)
    Disposal-wise, AGMs are like FLAs. They just don't have as much acid in them (basically).

    Nota bene: yes, Niel; higher than gels but less than FLAs. :D
    · Share on Twitter
  • tvengineer
    tvengineer Solar Expert Posts: 31 ✭
    #8
    Re: Any hope for these batteries?
    niel wrote: »
    edit to add:
    from your post you made while i posted i looked for further info on these batteries and they are agm.
    http://www.digikey.com/Web%20Export/Supplier%20Content/Enersys_842/PDF/Enersys_HX_RangeSummary.pdf
    do note that there are specific discharge specs given so you can test them. you can charge them at high rates, but they need to be kept lower than a specific voltage point set for switching out of bulk as agms are not to outgas or damage to the batteries can occur.

    Thanks....
    The plan for now.. is to get them home and on a slow charge to float.. then figure out what to do with them later :p

    I have 2 x 200 watt solar panels that I have been waiting on $$$ for batteries and wiring . to get into service.. so next is to get that installed and let the sun keep these at float charge for emergency power :D
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: Any hope for these batteries?

    great. what charge controller are you using for them?
    · Share on Twitter
  • tvengineer
    tvengineer Solar Expert Posts: 31 ✭
    #10
    Re: Any hope for these batteries?
    niel wrote: »
    great. what charge controller are you using for them?

    I had a prostar (morningstar) 30M that I was going to use..
    But I used it for another project ;)

    So I need to get another...

    I am really coveting the Morningstart TriStar MPPT 45...
    But it is so $$$$$$$$$$$$

    Then again.. I just got free batteries :blush:
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #11
    Re: Any hope for these batteries?

    if in the meantime you need to get a charge into the batteries i can gather by your username that you can devise something regulated to them. they only specify the float charge in the specs i cited so you could bring it up to 14.4v manually (a kind of quick bulk charge) and don't let it go over that. after that allow it to float, but i suspect their float charge to allow more current than standard controllers in the ups function or they would never recharge back up. i think a linear regulator may work in the meantime set for between 13.5v and 13.68v by their pdf spec sheet.
    · Share on Twitter
  • tvengineer
    tvengineer Solar Expert Posts: 31 ✭
    #12
    Re: Any hope for these batteries?
    niel wrote: »
    if in the meantime you need to get a charge into the batteries i can gather by your username that you can devise something regulated to them. they only specify the float charge in the specs i cited so you could bring it up to 14.4v manually and don't let it go over that. after that allow it to float, but i suspect their float charge to allow more current than standard controllers in the ups function or they would never recharge back up. i think a linear regulator may work in the meantime set for between 13.5v and 13.68v by their pdf spec sheet.

    Yes.. I can figure something out ;)

    I don't want to parallel them just yet .. (not knowing their condition)..
    So one at a time..
    I have (at home) a 15amp regulated adjustable supply...
    I'm just going to set it manually to get a charge current of about 5 amps..
    then adjust a little at a time until they reach around 13.5 volts. Again.. 1 at a time...

    then to figure out a way to see if they have similar discharge potential...
    I don't know.. maybe put 4 of the same value light bulbs on all of them and watch as they get dimmer :p
    I am hoping to string them as 2 series 2 parallel for a 24volt inverter that I happen to have around :D
    · Share on Twitter

Categories