Used Forklift Battery

n4wff
n4wff Solar Expert Posts: 48 ✭✭
in Solar Beginners Corner #1
I am able to purchase 2 - 36v forklift batteries for scrap value ($154 each). I do not know the amp hour rating. The plant I am getting them from replaces the batteries when the lift will not go a full day on a charge. My thinking is since I have a 48v system, take the 2 batteries and check the individual cells and find the ones with the highest specific gravity and cut and replace the jumpers to bypass the bad cells, and make 2 - 24v batteries. Is there anything else you would suggest?
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Used Forklift Battery

    Sounds like a plan, I might go ahead and pull the cells your not using, if possible. I think they will expand as they sulfate making servicing any of the others very difficult. but perhaps that's a misconception of mine.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #3
    Re: Used Forklift Battery

    Sounds like a good plan... user "Adas" from Hawaii did this a few years ago and setup a large off grid fabrication business and was very happy (last I heard).

    http://forum.solar-electric.com/search.php?do=finduser&userid=1074&starteronly=1&contenttype=vBForum_Thread

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • H2SO4_guy
    H2SO4_guy Solar Expert Posts: 213 ✭✭✭
    #4
    Re: Used Forklift Battery

    What a GREAT opportunity! They are quite robust, just be careful, there are a lot of ways to get injured with fork truck batteries. They will scrap for more than that! You can always keep the balance of what you are not using on float charge to use when some cells fail. I bought 54 of the 2 volt cells (AGM) with that purpose in mind. A 48 volt pack with 30 spares in my case.

    You can have some real fun with those, what a neat deal. I wish you the best and let us know how it is working out.

    Skip
    12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
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  • n4wff
    n4wff Solar Expert Posts: 48 ✭✭
    #5
    Re: Used Forklift Battery

    I have the 36v batteries in my possession, just have to figure the logistics of getting them home. They are heavier than originally thought, 2150lbs instead of 1100, and rated for 930AH. The voltage is 35.6 in one bank, and 35.9 in the other. I do have a question though, to reconfigure the battery to 24 volts, can the lead be safely soldered to with a pencil torch? If not what is the best way to connect the terminal ends?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: Used Forklift Battery

    most use wire with clamp type connectors, but if welded is what you want i think it better to try an electric weld rather than risk damaging the battery.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #7
    Re: Used Forklift Battery

    What I have seen done is to remove the straps with a hole saw, then tap the drill hole. The battery people remove them with a counter cutter kind of like a hole saw. The other way would be to use a sawsall to cut them in half and then drill and bolt cables to them. Poke around on google " How to dissemble a Forklift battery ", all kinds of Information.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
    Re: Used Forklift Battery

    i may be misunderstanding here what he's after as i thought he was looking to assemble them, not disassemble.
    why am i tempted to say #5?:p
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #9
    Re: Used Forklift Battery
    niel wrote: »
    i may be misunderstanding here what he's after as i thought he was looking to assemble them, not disassemble.
    why am i tempted to say #5?:p
    How would you assemble 2, 36 V batteries into 24 or 48 v without disassembly and re-assembly of the output ?? Each battery would have 18, 2 v cells, right ?? He'll have to remove some of the straps and make jumpers for others to get them into strings of 24 V. If your talking about taking them out of the cases, forget it, thats a major pain.
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  • n4wff
    n4wff Solar Expert Posts: 48 ✭✭
    #10
    Re: Used Forklift Battery

    Thanks for the replies. I apologize if I wasn't clear. The batteries are at work now, sitting on pallets. I have to find a trailer to haul them to the house that is low enough to pick it up with the backhoe bucket, and a chain. As far as the battery cases, I want to leave the cells in place, and just bypass the weak cells in each case. I have some 4/0 copper to make the jumpers, I just did not know how to connect it to the battery terminal. My original plan was if the lead on the battery can be safely melted, I would like to solder copper to it for a secure connection, but big battery banks scare me more than 240v ac. Torches, sparks, and outgassing hydrogen remind me of images of the Hindenburg. Blackcherry04 - The hole saw is a great idea! How deep can I safely drill into the battery? How easy is it to strip out the lead threads?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #11
    Re: Used Forklift Battery

    ok sorry for my misunderstanding and blackcherry does have some good ideas, but just be careful and take your time.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #12
    Re: Used Forklift Battery
    n4wff wrote: »
    Thanks for the replies. I apologize if I wasn't clear. The batteries are at work now, sitting on pallets. I have to find a trailer to haul them to the house that is low enough to pick it up with the backhoe bucket, and a chain. As far as the battery cases, I want to leave the cells in place, and just bypass the weak cells in each case. I have some 4/0 copper to make the jumpers, I just did not know how to connect it to the battery terminal. My original plan was if the lead on the battery can be safely melted, I would like to solder copper to it for a secure connection, but big battery banks scare me more than 240v ac. Torches, sparks, and outgassing hydrogen remind me of images of the Hindenburg. Blackcherry04 - The hole saw is a great idea! How deep can I safely drill into the battery? How easy is it to strip out the lead threads?
    Some of this is based on how much you value your work and the end result. A hole with a lag bolt and a couple washers might work ok, till it didn't, Only you know that.

    You want your connections tight, but 13-17 ft lbs is plenty. Using a Bolt on jumpers is fine, on your terminals I'd do the below. Once you identify a bad cell, do a practice test and up your skill level and refine the process. You might find that you can modify the tap by grinding out some of the thread forms on it since the lead will be very soft and gooey and lots of swarf. Use a vacuum cleaner as you tap and drill.

    If you stay in the center of the post a 1/2 to 3/4 inch or more should be no problem. The best way is to use a Stainless Steel threaded stud, where you put in a say 1 1/2" length ( half into the post ) then use nuts and washers like a regular threaded 5/16" or 3/8" battery post. This way once you put the stud in you'll never have to remove it. I'd use a plug tap to thread them. I don't know your skill level, if your capable, this is where the best success would be. 5/16" is ok or 3/8" if you want larger.

    Another way ( less work ) is to use a stainless steel double threaded stud that has wood screw on one half and a 5/16 " -18 thread on the other.

    http://www.mcmaster.com/#catalog/119/3154/=ok527u


    If these are a little long, they can be cut off on the wood thread end or use a spacer on them.

    Attachment not found.

    One other thing I'd probably do is, after I removed the strap is to clamp a set of Visegrips on the post so they would stop / or give you a visual signal that you were not applying to much torque on the post as you were drilling, tapping / and tightening the bolts. It might be easy to twist one to much.
    .
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  • Brianellul
    Brianellul Solar Expert Posts: 95 ✭✭
    #13
    Re: Used Forklift Battery
    n4wff wrote: »
    I have the 36v batteries in my possession, just have to figure the logistics of getting them home. They are heavier than originally thought, 2150lbs instead of 1100, and rated for 930AH. The voltage is 35.6 in one bank, and 35.9 in the other. I do have a question though, to reconfigure the battery to 24 volts, can the lead be safely soldered to with a pencil torch? If not what is the best way to connect the terminal ends?

    Good deal indeed. I too had the oportunity to get a set of forklift batteries (48v) which were destined for scrap. In my case they did not want any money except for me to take them away from their premises. Unfortunately, the batteries had been lying around, uncharged and with low levels of water. They were free so I still decided to try them out. Similar to yours, I used an angle grider and seperated all cells. I removed all cells from the box and washed them well. I topped them up and charged them for a long time. Finally selected the best 12 cells and placed them in my battery box (another reason why I needed to seperate them). To connect them I used 10mm stainless steal lag bolts with spring washers. (as Blackcherry04 suggested)
    In my case they didn't last long :cry: and after 2 years I threw them away. They had been severly abused and abandoned for a long them and I wasn't expecting any miracles from them. Having said that, I did put my hands on another set of 'scrap' forklift batteries and these are still going strong after 6 years of use.
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  • n4wff
    n4wff Solar Expert Posts: 48 ✭✭
    #14
    Re: Used Forklift Battery

    Update. I am not quite as enthused about the batteries. I still have them at work, but I am able to use a charger from the business next door. After charging overnight, and the batteries allowed to sit for a few hours, they measured 36.4v and 36.6v. After a full charge, all the cells were close to being equal with the specific gravity around 1.175, and the voltage around 2.01 - 2.05. I hope I am not wasting my time with them, but I am going to try cycling them a few times and see what I get.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #15
    Re: Used Forklift Battery
    n4wff wrote: »
    Update. I am not quite as enthused about the batteries. I still have them at work, but I am able to use a charger from the business next door. After charging overnight, and the batteries allowed to sit for a few hours, they measured 36.4v and 36.6v. After a full charge, all the cells were close to being equal with the specific gravity around 1.175, and the voltage around 2.01 - 2.05. I hope I am not wasting my time with them, but I am going to try cycling them a few times and see what I get.
    The low SG sounds like sulfation. But one unlikely possibility is that if they were boiled too hard they might have actually been losing electrolyte out the vents in the form of spray. Replacing that with just distilled water would result in the SG going steadily down over the years.
    A good test will be to actually measure the capacity by discharging them to a 50% level or so, or else measuring the internal impedance (carefully using an appropriate tester which applies a pulsed load current)
    SMA SB 3000, old BP panels.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #16
    Re: Used Forklift Battery

    If you can recover them you'll have to spend many hours or days equalizing them. I don't know what equipment you have, but it's a long process. As long as you can get some rise in the SG's, your on the right track. Keep hammering them and when the temperatures get to 110-120 F, stop and let them cool off overnight.

    Remember to temperature correct the SG reading. Battery Recovery Specialist is a Job Title.
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  • n4wff
    n4wff Solar Expert Posts: 48 ✭✭
    #17
    Re: Used Forklift Battery

    Update #2 I have it temporarily hooked up! Sitting in the cool A/C, running off battery power for about 30 minutes now. 8) My house is pulling 2250W @ 56.9A DC. Batteries are down to 47.1V and holding steady. I am going to run it for another hour or so then put it on equalize charge overnight. Thanks everyone for the info. This is by far the most knowledgeable forum on the internet.
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