Author Topic: 2nd Hand Forklift Battery - Questions  (Read 3765 times)

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2nd Hand Forklift Battery - Questions
« on: November 03, 2015, 03:03:59 AM »
Im considering the purchase of a 2nd hand forklift battery. Its 48v 775ah from a Crown forklift. Price seems OK but freight looks to be a killer. However, I would like an opinion from the group please about the suitability for my situation and if you recommend I stay away.
Ive been off grid for 4 years. I have a micro hydro/solar mix and use about 5kwh per day. The hydro does most of the work when water is flowing and clouds are common and solar takes over when the creek dries up. Works well and I supplement the solar with generator/charger runs as required. I have a small battery storage comprising 4 x 220 ah deep lead acid deep cycles which I am not impressed with.

The forklift battery is way bigger than my current storage but I can see many advantages to having good capacity. The owner tells me (this is the problem) that the forklift will only work for 2-3 hours before they have to charge it again. Cells have been tested and there are no shorts but it struggles to delivery the 500ah necessary to lift and operate. So, does this represent an opportunity to give the battery a second life for me at home here or should I steer clear? The owner also reports one cell was replaced in 2011.

Appreciate any comments please as soon as possible.

Best regards


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Re: 2nd Hand Forklift Battery - Questions
« Reply #1 on: November 04, 2015, 12:11:00 AM »
i think what he means is the battery struggles to deliver the 500 amps needed to lift and operate. combined with the report that it only works for 2-3 hours indicates that the battery is mostly crap.

you might want to just spend the money and buy lithium iron phosphate batteries.. about a year ago i figured they are on par with lead acid for realistic estimates of lifecycle cost.


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Re: 2nd Hand Forklift Battery - Questions
« Reply #2 on: November 04, 2015, 06:42:37 PM »
I've had good luck with used traction batteries, been off-grid more than a decade with a 48V/500Ah series/parallel bank of second hand wheelchair batteries (they're tired and need replacing now though).
These were all past the end of their useful life in high-drain wheelchairs, running a house is much easier on them with lower peak current draws.

A few things to consider:
- Check the cells visually, if they have a clear plastic case is there a pile of crud down the bottom (from damaged plates)? If the case is not clear have a good look for plate damage through the filler caps (using appropriate eye protection).
- How old are they?
- What's the condition of the cases/ terminals?
- Check the specific gravity of each cell when they're charged, are they reasonably close?

At a guess, 2-3 hours forklift use could well be more than your 5kWh/ day so they might be worth getting, having said that I wouldn't pay much over scrap value for them (including freight).
If they turn out to be rubbish you might have to pay to get rid of them...



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Re: 2nd Hand Forklift Battery - Questions
« Reply #3 on: November 05, 2015, 06:43:05 PM »
Forklift batteries come in 2 types, AGM and flooded. I assume you are looking at a flooded type. We have 7 lifts of different types at work (warehousing paper products).

The person in charge of the building does not have the technical background or company support ($$$) to do things correctly.

3 times now we have had lift batteries die because of improper use. Once a 24v battery was allowed to drop to just above 8 volts in transit to us in a crate. Crown and Deka sent reps who could not or would not revive the lift. Because I have a reputation as a Mr Fixit, the #2 man told me I could have whatever parts I wanted from the lift as Crown doesn't buy old machines and Deka offered him $60 for the battery as scrap. I asked permission to attempt a repair and was given the okay.

All I had to do to revive the battery and lift was force charge it with a 6 amp car battery charger (one half at a time). Once the voltage was high enough the on-board charger began to work. Two days of onboard charging and the lift correctly worked again and still works 3 years later with the same battery.

The other lift with a ruined battery is a Crown SP. This lift would turn on but not move. The Deka rep claimed the battery had 4 bad cells and marked them and offered to sell us a new battery. I tried charging the battery out of the lift with no initial luck. 4 cells refused to come up. But knowing we have old poorly maintained chargers, I charged the battery while reading each cells voltage and realized that charger was cutting off at 28.8v. It was set for the AGM's we have on our walkies. We have 5 chargers and one other charger had an Anderson connector that was the correct size so I tried that one. It cut off at 30.5v and that was enough to equalize the battery and revive the lift. That same lift went dead in an aisle this week and I swapped cables with a walkie with an onboard charger to boost the battery enough to get it back to the charger. The onboard charger of the walkie also cuts off at about 28.8 and would only put 1/4 of a full charge on the flooded battery, but that was enough to operate the lift.

Flooded lift batteries can withstand a lot of abuse, but will not work correctly unless you can force the voltage high enough to overcome the sulfated/discharged cells. Less than 2 volts is the difference between charging AGM (28.8v) and flooded (30.5 +/-). If you aren't adding water and churning the electrolyte in a flooded lift battery it will sour fast. If you get a battery a lot larger than you will cycle in a day, then you need some way to equalize the battery once every week or two.

Bruce S

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Re: 2nd Hand Forklift Battery - Questions
« Reply #4 on: November 06, 2015, 10:33:24 AM »
Might be a good idea to post a picture!
If memory serves me right TomW had a set that was actually flooded NiCds! These probably are not, tho.
TomW had to keep his on their side so the fluid would flow correctly.
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Re: 2nd Hand Forklift Battery - Questions
« Reply #5 on: December 05, 2015, 07:40:08 PM »
 A big thank you to all of you for your excellent comments and advice. I really appreciate it. I didn't receive email notifications of your responses so not sure whats happening there.
I ended up missing out on that battery. Its probably just as well as the freight was way too expensive. I have however located a local battery that the dealer says will be replaced in a week or so. I will have the first offer so Ill report back what I find.

Here is another question. Two of my 220ah so called deep cycles have now failed inside two years. They are 12v batteries and in both cases, one cell has given up. Im told by the local supplier this is a cell short and the entire battery is now stuffed. My reckoning says if a cell is shorted, then I should always get around 10v from the 5 remaining cells. However, when I charge one of these dud batteries, it will retain 12.5 - 13v for quite some time and with self discharge will eventually drain. One of these is currently reading 12.1v and has been sitting outside unconnected for over one month. So, my question is.....does this sound like a shorted out cell? if so, why the 12+v voltage? If not, then what do you think is wrong and can it be brought back to serviceable life. My local battery dealer says take it to the scrap metal man.
Appreciate your valuable comments.

Mary B

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Re: 2nd Hand Forklift Battery - Questions
« Reply #6 on: December 06, 2015, 03:41:03 PM »
Some have revived batteries by shaking them to stir up all the gunk then pouring it out along with the acid. Rinse with distilled water, drain and refill with battery acid. "might" bring it back to life. Wear protective gear if this is attempted!


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Re: 2nd Hand Forklift Battery - Questions
« Reply #7 on: June 25, 2016, 08:14:54 AM »
A better idea is to look local at scrap yards. Call around and see if they sell batteries to the public. Mine does. Head on down with a voltmeter, flashlight and a hydrometer. I got 4 brand new bulldozer VRLA batteries this way for 15 bucks a pop. 8d batteries. Not designed for deep cycling so much but at that capacity and cost it didn't matter. When you find a decent cell that holds more than 11 volts, 12 is even better buy it and give it a long slow charge. Test the specific gravity if its getting up to at least 1.250 you can let it rest a night and put it on a harder 15-16 volt equalize charge for around 2-3 hours. If its below, whip out the baking soda and a plastic container. Wear some cheap clothes and wear gloves and goggles. Flip the cells out, wash them with hosed water. There is the possibility, especially if its heavily corroded that they will short out. You can also siphon but this may not get all the acid. Once its nice and clean you fill it with distilled water and charge it. This will make an acid starved electrolyte and it makes it really easy for that sulfate to pull off. You should see the specific gravity rise. Discharge to 12.2 and recharge. Dump the weak acid mix and put new acid in. If you want a longer life batter, lower the acid content to something like 1.200 specific gravity but keep in mind it will charge slower and discharge slower. This also makes it easier to freeze.