48v wet cell battery

homerramirezhomerramirez Solar Expert Posts: 102 ✭✭
Hi guys, :D , can you give me some advice?

I have an oportunity to buy a cheap used forklift battery, the guy has 3 and I will like to pick the best one, Is there any way to find out how much life is left on the batteries?, what the specific gravity should be per cell? or whats the voltage reading should be?, what things I should look for?
My system can't be grid tied (no UL panels) so I must look for good deals on large battery. ( I have to separate the cell terminals to come up with 2 parallel of 24v for my PV and inverter rating)

any reply is apreciated.

Comments

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: 48v wet cell battery

    that might be tough to answer as they may quick charge it just for you to buy it so voltage and sg readings may appear good. look for anything odd or not normal as it may have a crack in the case or sulphation that may make the electrolyte seem off to the eye. do look at the normal stuff too as real low voltages or really bad sg readings may be a dead (pun intended) giveaway that the less savy con artist wouldn't think of. you are pretty much taking a chance, but talk to him too to see what care was taken and if they happen to trip themselves up with bs.
    odds are they will have new batteries in the forklifts so you can try to see what the scoop is with them. try to measure any voltages at least 2-3 hours after they throw the charge switch off, but they may charge overnight making this impossible for you to know what they are like at rest for they will start using them immediately.
    it would be rather tough for you to load test each of those batteries and the real test would be what they did in the forklift. tell them a real cheap price because if it's bad you are stuck without a battery and must pay for its dispossal.
    let us know what happens in any case.
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: 48v wet cell battery

    Hey R,

    If you could borrow a meter to measure conductance( since they are expensive and would not make any sense to buy just to test those batteries) and measure the conductance of each cell in comparison to say that of the new cells(if the new ones in the forklift are identical to the ones they are selling) then you get a gauge on a sulfation that maybe present by virtue of the reading showing the active surface area on the plates even if they have fully charged the batteries. It is a long shot but depending on the asking price it may be worth your while to even rent one if possible. Just my 2c:cool:

    Cheers...
    Damani
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 48v wet cell battery

    Buy used batteries is like going to Vegas and rolling the dice - only not as much fun.

    Specific gravity needs to be checked against the manufacturer's specs. Battery voltage needs to be checked over several days (without charging in between). Load testing is a good idea too (I've never seen a unit for a 48 V battery, though).

    So just how cheap are you getting these for? Scrap metal price would be okay. :p
  • mike95490mike95490 Solar Expert Posts: 8,429 ✭✭✭✭✭
    Re: 48v wet cell battery

    Also, forklift batteries, are made for mechanical strength, the chemical package is not designed for recharge efficiency. You may need more power to charge them. (130W recharge vs.. 120W , for 100w used.)
    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 ,

  • peterakopeterako Solar Expert Posts: 144 ✭✭
    Re: 48v wet cell battery

    Hi there look inside the battery if you see a lot of white spots or big white areas that is sulphation and is bad news. by the way there is a reason that the batterys are changed so rethink before you buy.

    Greetings from Greece8)
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: 48v wet cell battery

    Hey pete,

    the only cells that i came in contact with that you can see the plates are telecom cells(like C&D). I had some and the plates were held in transparent case where you could see the flat side of the outside cells and in those cases you can see if any sulfation has taken place. as for traction cells, I have some by hawker, you can only just see the top edge and not nearly enough to see any signs of sulfation. I am not sure he would be able to see evidence of sulfation on those forklift cells since their casing are usuall black or opague with only one small opening to allow for addition of water.

    Cheers...
    Damani
  • BB.BB. Super Moderators, Administrators Posts: 29,639 admin
    Re: 48v wet cell battery

    Search for posts by "Adas"... He has done pretty well buying old forklift batteries to run a fabrication business off-grid in Hawaii.

    I don't remember him doing anything special other than filling up the cells, charging, and with the batteries he got--he could wire around the occasional bad cell (such as make a 32 volt battery into a 24 volt bank).

    Just figure out your costs if the batteries are no good (price + shipping + disposal/recycling) and see if it is worth it to you.

    Also, I would plan on having closer to the 13% of solar current to AH capacity vs 5%... I am sure old forklift batteries self drain and require more equalization than a standard deep cycle/AGM battery in good condition.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peterakopeterako Solar Expert Posts: 144 ✭✭
    Re: 48v wet cell battery

    Hi damani,
    Maybe there are different battery's used here in Greece.
    Yes the are black but the top filling part you can pull off and look deep inside the battery cell.

    Sorry if this is not for the states.

    Greetings from Greece
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: 48v wet cell battery

    Hey pete,

    I am not from the states. However here in the Caribbean we do use quite alot of industrial type material from the states. The industrial/commercial traction batteries(submarine, forklift) that i have seen you can't take the top off only a small cap(~1" dia, usually one) you can remove to access inside the battery and since the cases are at least opague you don't get alot of light inside the cells to see inside of them.

    Cheers...
    Damani
  • homerramirezhomerramirez Solar Expert Posts: 102 ✭✭
    Re: 48v wet cell battery

    Thank you guys, right now I have 400AH AGM wired @ 24v, I understand that my 1300w of PV can support about 800AH @ 24 volts, I paid close to $1100.00 dlls. just for the battery bank, still have to leave my fridge runing while going to work, by the time we come back my controlers(3 PWM) are on float and my RE production is wasted and at night it will not have enough to use and keep the fridge going.

    I can't have it grid tied because my panels as been said are no UL (along all restrictions from the power company which is a cooperative and is more restrictive than a private power co. ) but are to my opinion of exellent quality (130's watt Sunsei).

    now my only choice is to buy a used high AH battery, thanks to you all guys for the feed back, also thanks B.B. for the tip about if there is a bad cell on a 36v batt. to skip it and wire it to get 24v.

    that's a very good one....... always learning from you guys.

    thanks again. ;) :D
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: 48v wet cell battery

    To your specific questions:

    Battery Discharge voltage and Spec Gravity
    SOC S.G. 12v 48v 6v 24v
    100 1.277 12.73 50.93 6.37 25.46
    90 1.258 12.62 50.47 6.31 25.24
    80 1.238 12.50 49.99 6.25 25.00
    70 1.217 12.37 49.49 6.19 24.74
    60 1.195 12.24 48.96 6.12 24.48
    50 1.172 12.10 48.41 6.05 24.20
    40 1.148 11.96 47.83 5.98 23.92
    30 1.124 11.81 47.26 5.91 23.62
    20 1.098 11.66 46.63 5.83 23.32
    10 1.073 11.51 46.03 5.76 23.02
    Open circuit SOC, several hours of rest after charge or discharge

    Sulphation will tie up sulphur in lead-sulphate crystals resulting in low sulphuric acid concentration in electrolyte. Shows as low specific gravity after full charge attempt.
  • BB.BB. Super Moderators, Administrators Posts: 29,639 admin
    Re: 48v wet cell battery
    ... just for the battery bank, still have to leave my fridge runing while going to work, by the time we come back my controlers(3 PWM) are on float and my RE production is wasted and at night it will not have enough to use and keep the fridge going.

    I am not quite sure what you are saying here... If you have 400AH AGM wired @ 24v--:

    50% 400AH * 24v = 4,800 Watt*Hours of storage...

    The typical Energy Star Fridge will use around 1-2kWhr per day... Which means you should have ~4.8 to 2.4 days of storage with your current bank and a reasonably efficient inverter+fridge.

    The issue of not being able to store 100% of a day's production with an Off-Grid implementation--yea-that is one of the big issues with Off-Grid systems. They have to be either larger than you need, or you risk having to run the genset more than you planned.

    If you have optional loads (such as a x,000 gallon water tank, electric washer that you only need a couple times a week, vacuuming, etc.) that you only run when the Sun is out--or will be made up in the next day or two--will help.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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