Forklift battery salvage attempt

blacktape · March 2010

Hello All! First post (be easy!)

Sorry it is a bit long but I really could use some guru tips - maybe cut right to the bottom if your pressed for time...

Crazy story cut short - I got a used forklift battery from a guy was dropping off today at our local batt recycling shed at the dump. He agreed to follow me home and drop it off for $40. I don't know if it is the worst or best $40 I have spent and trust time will tell.

Battery: Brand is "Varta" 24 V, 12 cells. 870 Ah. 1850lbs Don't know how old. Made in Canada.

The guy tells me he needed a new one for his lift - said he used the lift once every few months and would have to charge it up every time. Said he did add water. Probably NEVER been equalized I'm guessing. Batt was kept indoors so it never froze.

I cleaned the exterior cell tops up a bit and all seems to be in OK shape, nothing broken, leaking etc - cells housed in a steel box. "As-is" I got about 21 Volts on my needle-type multi-tester. Then I took caps off and noticed ALL cells the plate-tops were visible - no electrolyte covering them. Got some jugs of de-ionized water and added 1 litre to each cell - this brought fliuid level about 3/4" over the tops of the plates. I think 1L = 1 Quart sort of??

I don't have a PV system yet set-up - this battery literally fell from the sky timing-wise. I only have 2 trickle chargers for motorbike/auto use rated 12V @ 1 Amp. I halved the cells so now I have 2 banks of 12V and the trickle chargers are on each side. Sure seems like David & Goliath to me!!!

My goal is to somehow:

A - determine if this batt is useful or junk. It is cold outside here at night - I have it covered in blankets right now w/ 2 chargers 1 on each 12 V side ( I halfed it as above).

B - "what next" - do I try and fnd a charger with equalizer setting and try that after I get them fully charged - assuming full charge can be achieved?

C - How long to charge this beast at 12V @ 1Amp trickle? Days?

D - Stabilize this beast if useful until I get my PV system up in another month or 2 - I have 360 PV 6x6 cells to solder over the next few months sitting in boxes beside me as I type this!!

E- if this batt was never equalized would it likely be destined for the dumpster?

F- after I get some charge into the batt I was going to take off all the jumpers and test each cell individually and see if there are dead ones. What would be an esy way to see if the batt will hold a charge - use it hard, use it gentle, or let it sit out in the cold with no charger on it and test it day by day????

I'm basically out of my league and now have a ~ 2000lb batt in my yard that I thought might be a good score. But it might be a disaster??

I did buy a hydrometer but when do I use it - after a full charge? After equalizing? How to ensure the resident electrolyte mixes with the new water I added?

A friend has a forklift batt charger he will bring over tomorrow, but I am wondering IS there a specific process I should be following to bring this batt back to full-service so I don't screw this batt up worse OR hurt someone? I assume the forklift charger charges automatically on "deep-cycle" mode?

I put the trickle chargers on cause I was afraid the batt may freeze outside overnight, and with the small hope they will actually achieve a full charge.

Sorry for the way-long story and multi-questions......I really look forward to hearing your advice and contributing in the future when I learn more day by day! Very glad to have this awesome resource available - aren't we lucky! I'm pretty excited about entering the world of solar.

Thanks kindly,
J

niel · March 2010

Re: Forklift battery salvage attempt

i can't say if it's good or not, but being he said he had to charge it t think it meant it sat for many months and it drained down so in order to operate the lift a charge had to be shoved on it and who knows if he ever fully charged it? i'm confident there is some sulfation on it. all you can do is charge it fully and see how it is under load.

blacktape · March 2010

Re: Forklift battery salvage attempt

OK - thanks for the reply Niel.

My friend dropped off a 36V forklift batt just now- so I think it of no use. It is very old and does not have a equalization mode. I need a 24V or 12 V charger.

Niel - to attempt to get rid of sulfation = equalization charge?

I think it best that I buy a new charger from an auto store with several voltage, amperage, and with equalization mode - if one exists here in our small town!

Any other tips / thoughts would be appreciated.

thanks!

BB. · March 2010

Re: Forklift battery salvage attempt

This seems to be the common method of doing equalization:

Corrective Equalization - Method

Corrective Equalization can take a very long time depending on the degree of sulfation. It is not recommended to equalize with a generator as some generators produce low grade AC that is not properly filtered by the inverter. This is especially true at higher voltages.
If you have hydrocaps remove during equalization.

Set charging controls to the highest voltage allowable by the charge controller (inverter). If the bank is severely sulfated or available current is very limited, charge control can be removed or by-passed. Temperature should be monitored very, very closely and keep below 125ºF.

Charge at a low DC current (5 A per 100 AH of battery capacity). If grid power is not available use solar panels or a good DC source when possible. At high voltages, charging with generator can be difficult and hard on the inverter.

Once an hour, measure and record the specific gravity and temperature of a test cell. If the temperature rises above 115ºF (46ºC) and approaches 125ºF (52ºC) remove the batteries from charge. (For temperature measurement choose a center cell, if applicable).

If severely sulfated, it may take many hours for the specific gravity to rise.

Once the specific gravity begins to rise the bank voltage will most likely drop or the charging current will increase. The charging current may need to be lowered if temperature approaches 125ºF (46ºC). If the charge controller was by passed, it should now be used or put back in line.

Continue measuring the specific gravity until 1.265 is reached.

Charge for another 3 hours. Add water to maintain the electrolyte above the plates.

Allow bank to cool and check and record the specific gravity of each cell. The gravities should be 1.265 ± 0.005 or lower. Check the cell electrolyte levels and add water IF necessary.

To avoid this situation it is recommended that a specific gravity reading of one pilot cell is measured and recorded on a regular basis when it is thought that the bank is fully charged. The measurement should be compared to previous readings. If the measurement is lower than the previous reading a longer absorption time and higher voltage setting should be used. Note as stated above, the longer the absorption time and the higher the bulk voltage, the more water will be consumed but less equalization will be required. Note: the specific gravity should rise as the cells use water. Look for trends in the specific gravity over a period of time and make very small adjustments as necessary.

Caution: If you have HYDROCAPS, remove during equalization.

One user here (adas) has "recovered" several fork lift batteries for his use. He had some 36 volt models that he could by-passed past bad cells and make into a 24 volt bank (not all jumpered cells where bad--so he could keep those individually charged and use them later if another cell went bad).

48 v forklift battery

-Bill

westbranch · March 2010

Re: Forklift battery salvage attempt

Hi Blacktape, there are a couple of threads here about what to do, so do a search and have a good read. I recommend you do a bunch of reading of the FAQ on our sponsors site on batteries as well.

As to the batteries: you will learn a lot by trying to revive the one (2x12v) that you have before you go out and buy a new one or at least until you get one that has a good history... so don't throw it out, it will teach you a lot. And the price is right!

Look around for a good 3 or 4 stage charger, try Ebay, but in the meantime get a reasonable one (C. Tire) to get a charge on the bat and then do an EQ charge.

you will need a good Meter and a Specific gravity hydrometer. Do a series of readings now and write them down and so so each time you make a change in your treatment of the battery. these records can become invaluable.

Cheers

Enjoy
Eric

bryanl · March 2010

Re: Forklift battery salvage attempt

I don't think equalization is your first priority. A good charge should be. That will require a multi stage battery charger designed for a 24v system.

If I understand things right, an optimum charge rate would be more than 100 amps (2.4 kw). A 'trickle' charge would be around 10 - 20 amps. So it is going to be a challenge to get a decent charge going in a household environment. You might be able to use that 36v charger for the bulk mode phase but you might need to use a bit of wire as a resistance to limit current (if the charger doesn't do so itself). Be very very careful if doing such things.

Once you do get a full charge on the battery, you can see what it takes to drain the surface charge to assess condition and then look at specific gravity in each cell to determine if equalization charging is need.

More than likely your problem is going to be sulfation and the only way to address that that I have seen is the AC/RF technique and I don't know how any of the circuits or chargers I have seen will handle that size of battery.

The other possibility is to replace battery parts. I have seen some manufacturer user manuals that describe the process for their industrial batteries that can be 'repaired' this way but that begs the question of obtaining replacement parts and having the proper shop environment and tools for the task.

Industrial batteries should be used only in industrial environments by people with proper training and in an environment that has appropriate safety procedures and equipment in place and the resources to charge and maintain them properly. That implies, to me, that they are not good resources for home solar systems as a general thing.

bluetick · March 2010

Re: Forklift battery salvage attempt

If it were me, I'd not rush the charge, keep the amps going into the battery low to control the heat build up on the plates. High amps into a questionable battery can ruin any chance of recovery.

blacktape · March 2010

Re: Forklift battery salvage attempt

Thanks for the advice everyone! I will pass on using a section of wire as resistance and using the 36 V charger!! Way out of my league / safety zone and thanks for the disclaimer - I am well aware of just how much power / damage this batt (could) have... I walk around it like I'm on eggshells. Whether or not it is a good power sink for PV system is another thread - this is what I have now and want to try and save it becasue it could maybe save us $1000's - which would be a really nice bonus right now. I guess I will learn some good skills if nothing else....

Reading all your posts it seems there is no agreement about low amperage (1 - 20 Amps @12V) vs high amperage (80 - 100+ amps) given the current state. I can see why I would want a "hot" big amp charge but think I'll go the slow route as bluetick suggests (thanks). I have time...

I DID SEPARATE THE 24 Volt (12 cells) into (2) pairs of 6 cells in order to deal with 12 volts on 2 "sides" - I only have charge equip for 12V and know of no other alternative here.

Update:

Trickle chargers on the 2 sides (1 Amp @ 12V) overnight - no measureable result (V), not really suprise I guess.

Tried measuring SG only to find below 100 - enough of an idea the cells are hurting bad...

I did go to C. Tire (Hi Eric - thanks!) and bought a 4 stage $125 charger with a pulsing mode hoping to address sulfation and put a good charge on.

I tried charging first one 12V "side" (6 cells) at 10 Amps but soon got an error code "sulfation or damaged cell" - manual said to use maintenace (pulsing) cycle for 24 - 48 hrs. So I could not get a charge at 10 Amps. I now have the maintenance cycle running (pulsing?) and there is some bubbles slowly coming up to the surface of each cell - this is a good thing I think.

Question is - I could not get the cells up to full charge before doing this "pulsing" action. I'm wondering if the charger is basically sending high current through the cells right now or some kind of other weird electric current action I have yet to understand....?? I get a bubble or two every 5 seconds in each cell approx. I want to leave this pulsing on overnight at least (if not a week?!) and see what happens.

Do you think this is the best course action given the situation I describe? I cannot see it harming anything as long as I keep an eye on fluid level an SG - as long as it is not sending high Amps through it to produce these bubbles...

It has been an interesting weekend. Needless to say my wife is mad.

Thanks!!
John

blacktape · March 2010

Re: Forklift battery salvage attempt

I'm confused reding this all over again.

Disconnect the pulsing action generated by the maintenace cycle on the charger? - this is connected and running right now.

and

Leave my teeny 1 Amp trickle chargers on for 2 weeks and monitor V and SG?

or

Attempt charge again after 1 day (or 2)? on pulsing cycle?

Group vote?

BB. · March 2010

Re: Forklift battery salvage attempt

Notice that some of us (at least me

) used a ratio of C/20 or 5% rate of charge for equalization--You have a huge battery (with respect to a standard car/small truck types)--and it is possible that the charger you got simply is not seeing "enough voltage swing" on the battery cells you are charging...

870 AH * 0.05 = 43.5 amps

Basically, above 5% charge rate--you could overheat the battery (you need to watch temperature) as it becomes 100% charged.

The battery, once ~100% charged, is no longer storing current/energy--It is instead producing Hydrogen and Oxygen gasses from electrolysis (roughly, electrolysis is 50% efficient, so 1/2 of the energy goes into making the gasses, the other 1/2 goes into heating the battery bank).

You could put a 10 amp charger (around 1% charge rate) "forever" without overheating the battery... You would need to monitor water levels as it would tend to gas (again, once 100% fully charged).

If your battery is less than 80-90% charged, you could put upwards of C/8 or ~13% rate of charge into the battery to get it quickly charged (in less than 8 hours)--then run the equalization at 5% or so:

870 amps * 0.13 = 113 amps maximum

Not a small charger by any means...

By the way, a large/old forklift battery could approach 1-2% daily self discharge rate... ~10-20 amps for your size battery. A 1 amp charger would probably be "going backwards" in charging that size battery bank.

-Bill

westbranch · March 2010

Re: Forklift battery salvage attempt

I have found on a weak ''deep cycle " battery that if I try a high charge (15A) it will sometimes kick out, (Nautilus 15/10/2 A charger) but depending on the state sometimes it will take 10 A and other times only 2 A charge for days . which charger did you buy?

Essentially the 1 A trickle charge in your case will only be covering off 'natural degradation' of the plates (discharge) .

The bubbles are 'gassing off' when the water breaks down into H and O2 gasses. The gassing will mix the electrolyte and the water you added. EQ ing will do a better job of mixing ... more gassing off. If you can manually set the new charger to 2 amps it will be better. Don't forget to record the Voltage of the sells and total batt voltage each time it kicks out as this will tell you if you are gaining. After you think you have a charge you want to record the end V and let it sit for a min 3 hours - 8 hrs or more and remeasure...
at 1 amp i could be weeks. Depending on the health of your battery(s) you might see that trickle charger putting out up to 16 V...

HTH
Eric

niel · March 2010

Re: Forklift battery salvage attempt

remember guys this is not a 100ah battery we're talking about here as it is 870ah. a 1a trickle charger will never charge that battery in a million years. a light charge rate would be around 5% and equates to 43.5a. a float charge would be 8.7a or less, but that is good only to maintain an already charged battery and most likely even at this rate it would never reach full charge. some very light charging may take place with 20-30a.

blacktape,
you must find the bad cells as the charger indicates there are some and take them out. if you can measure individual cell voltages that would be good. check specific gravities of the cells too if you can. identify each cell with either a letter or number and mark down any info for each of the cells as you go and when if that is applicable. let us know what you are seeing here with each cell.

blacktape · March 2010

Re: Forklift battery salvage attempt

update 2:

After reading your advice this aft - I stopped the pulse / maintenance mode on the charger and waited about 30 mins. Then I was able to start a 20 Amp charge cycle - it has been on for 2 hrs and seems to be going OK - on 1 12V "side" - I split it in 2 12Volts. The cells charging seem to be bubbling quite actively not boiling but def popping away lightly. Sign of trouble perhaps or normal?

It is cold outside and the cells are not warm (on the side of the steel case anyways) - I have to buy a glass thermometer tomorrow. I'm a little leary of leaving it overnight / unchecked on this cycle although the charger is supposed to adjust automatically. Maybe I will drop it to 10A later tongiht before bed?

This is charging only 1/2 of the total batt cells (1 side - I am only charging 6 cells 12V out of the total 24V batt).

BB - you said "The battery, once ~100% charged, is no longer storing current/energy--It is instead producing Hydrogen and Oxygen gasses from electrolysis (roughly, electrolysis is 50% efficient, so 1/2 of the energy goes into making the gasses, the other 1/2 goes into heating the battery bank)."

Because there is no way the cells are fully charged, this gassing activity is trouble?

Eric - I bought the top of the line? MMaster micro-processor 2/10/20/40/80 charger.

Thanks for clearing up the charge Amperage questions I asked earlier Bill and Niel.

When I first tried to charge this morning, I think the distinct distilled water / electrolyte separation was interfering with the feedback to the charger so it rejected it and put out the error code? The heavily sulfated plates have something to do with it too for sure. I can only guess that now that the electroylte has mixed over 7 hrs and stirred things up on the pulse mode I mentioned earlier the charger has "accepted" the charge? Mind you I only tried 10A charge - not 20A this morning. ??

I'd love to get a better picture of health of the individual cells, but they are all connected in order to charge them as 12V and I thought I should get a best as possible charge on them before testing indivdual V and SG. ??

Really appreciate your help guys.

John

BB. · March 2010

Re: Forklift battery salvage attempt

You really need to measure the Specific Gravity and keep track over time...

The sulfur from the acid goes into the plates as the cell discharges. Recharging drives the sulfur into the water and raises the specific gravity again.

If you have sulfation--the Sulfur in the plates is converted to a crystalline form (over days/weeks/months and if stored with less than ~75% state of charge) which is difficult or impossible (depending on who you believe) to recover and drive back into the electrolyte.

So--what you would have seen if you where monitoring SG (Surrette website):

100........1.255 – 1.275
75..........1.215 – 1.235
50..........1.200 – 1.180
25..........1.165 – 1.155
0............1.130 – 1.110

A forklift battery may even have a SG above 1.275 from the factory fill.

If the battery is sulfated--you may see the SG stop at 1.200 or something... The extended equalization may cause that value to rise over time (good thing--recovering additional sulfur from the plates).

Checking all cells, you may find one that stays at 1.110 SG--that may be a shorted cell. bypassing/replacing that cell may allow you to use the rest of the battery for quite a while longer (works nice with a 36 volt fork lift battery pressed into 24 or 48 volt bank use).

Remember that specific gravity falls as temperature increases.

If you have access to the bus bars on the top of the cell--you can also do a quick check of resting voltage (no charge/discharge for 1-3 hours or so) to estimate Specific Gravity (if battery is around 77F) if you don't have a hydrometer handy:

Specific gravity = single-cell open-circuit voltage - 0.845
(example: 2.13v – 0.845 = 1.285)
Or
Single-cell open circuit voltage = specific gravity + 0.845

Remember that excessive equalization can have its own issues too... The Oxygen is driven to the positive plates and causes positive grid corrosion.

"Gassing Cells" with low specific gravity would, to me, indicate that the cells are sulfated (lead sulfate locked into crystals and not available for release back into the electrolyte).

You really want to monitor the cell voltage/specific gravity over time... That will tell you if you are improving anything or not.

blacktape · March 2010

Re: Forklift battery salvage attempt

OK - I understand what you Bill and Eric, Niel, are telling me and thanks again. I'm stuck on this situation right now: it seems as though I cannot get a charge into the battery (gassing/bubbling on 20 amp charge within minutes of hooking it up - on 6 cells only = 12V batt). The hydrometer instructions say quite clearly I wont get a good reading if I just added water - which I did 2 days ago now. So how do I get a SG reading that means anything? I told you I tried and got below 1.00 not good. Volts reads 11 on each side - this is after I tried a 20 amp charge on 1 side (12V) for 4 hours. I could try again but was worried about leaving it overnight unattended.

The charger has a "last resort setting" for heavily sulfated batts - considering that as my next option.

I could also try 40 amp charge setting as well and monitor temp / activity but have a hunch it will just boil instead of bubble....

I could also attempt 10 Amp setting for a few days as see what happens.

I was hoping to keep these cells altogther in order to charge and go from there, but like Niel says maybe I have to disconnect all cells and have a look - but still if the water hasnt mixed and sulphur is locked into the plates I think there is not much point? Or am I missing something?

Frustrating - but I knew it could be a "project"...
Thanks for listening!
John

BB. · March 2010

Re: Forklift battery salvage attempt

You have an 870 AH battery and did 20 amps * 4 hours = 80 AH... So, at best, you would have charged the battery by 10%...

A normal charge on that battery would by 120% of capacity or:

870 AH * 1.20 charge * 1/20 amps = 52 Hours to charge from dead @ 20 amps

You probably would try at least 20-40 hours of charging to see if you can move the specific gravity > 1.000 (pure water)...

I don't think you will overheat the battery with 20 amps--You can watch the bubbling in the cells--if it "vigorus" (rather than just a few bubbles)--then you are probably not doing much charging and instead doing electrolysis instead.

If you cannot get the resting voltage of the bank > 12 volts after a day of charging--I don't know--you may be wasting electricity.

The amount of current you are putting into that bank is still very low:

20 amps / 870 AH = 0.022 or 2.2%

2.2% is not much above the self discharge rate of an old forklift battery.

You may simply not have enough battery charger to really move the battery state of charge--and if the battery has too much self discharge--it may not be worth anything to you even if you get some life out of it.

Are all the cells reacting the same to the charge current?

-Bil

niel · March 2010

Re: Forklift battery salvage attempt

i say hit it with 40a as that's under 5% and is technically a light charge for a battery that size assuming the charger will feed power to it. try it with you supervising it or being nearby for at least 3-4hrs and then check on it to see if the voltage has gone up some. if it did go up then let it rest about 2-3hrs and see what the voltage falls back to. if it's notably higher than before you did this then continue your charging on it.
btw, while one side is at rest awaiting voltage readings then try it with the other side by charging it at that 40a rate. after about 6-8hrs of charging at 40a then see what the electrolyte readings are starting to do. this may indicate a dead cell or cells by this time even though it would need many more hours at this low charge rate to reach a full charge.
if the charger won't feed it at a higher rate of charge then either the battery is shot or the charger isn't right and possibly both. maybe find somebody with a hd automotive charger to start pumping in some amps to get things going just for an hour or so. this may indicate if you present charger isn't functioning right, but you can try it on a car battery too to verify its operation.

bluetick · March 2010

Re: Forklift battery salvage attempt

He's split the battery into 12 volt sections, hopefully he's just working with one side at the time, keeping a trickle charger on the other. The plates are sulfated, partly hard sulfation, non reactive or slow reactive, reducing the plate area and amp hour rating. To charge at 40 amps is too much for the area of plates that is readily active. The heat build up on the plate area that is reactive will ruin any chance of recovery of this battery.

As long as he keeps more amps going into the battery than the parasitic discharge rate he's halted any further sulfation. The only thing he has to loose by going slow is time and a few dollars worth of electricity.

If one cell boils when a charge is first attached suspect a shorted plate.

mikeo · March 2010

Re: Forklift battery salvage attempt

870 becomes 435 per side,

No it is still 870 amps,just at 12 volts and at half the watts.

wild01 · March 2010

Re: Forklift battery salvage attempt

blacktape, I use forklift batteries on my system, and am very used to them. They are built much heavier duty than anything else on the market. they do self discharge @about 1% a day, so if left to sit for 3 months they will be dead. (but not ruined) so there was probably nothing wrong with the battery when you got it other than a little sulfation. charge it at 80 amps for 8 hours, it isn't going to hurt the battery! a little bubbling is a good thing it will mix all that water you added into the acid, thus allowing you to get a good gravity read. charging at the higher amperage will also help break down any sulfation that the battery has. you won't hurt the plates, they are EXTREMELY thick.

again hit each side (12 volt) for 8 hours at 80 amps finish at 40 and then let it rest for a day and test the volts and sg. cycle it as hard as you can 3 or 4 times (run it down as fast as you can and recharge it immediately) and it will probably come back to almost full factory specs. also keep in mind that amp hour ratings on forklift batteries are usable amp hours not total, and are rated at a 6 hour discharge. so your 870 amp hour battery is comparable to a 1500 amp hour standard deep cycle. (which are rated at 100%dod on a 20 hr rate)

PLEASE NOTE *****the above instructions are for forklift batteries only*****
try this with an L16 and you WILL ruin it, the plates just won't take the abuse

niel · March 2010

Re: Forklift battery salvage attempt

80a charging would assume there are not any dead or shorted cells. he still should approach this with some caution so that the other cells do not get smacked from the existence of any bad ones.
btw, l16s can take a 10% charge rate.

blacktape · March 2010

Re: Forklift battery salvage attempt

Thanks for chiming in wild and blue and others...

Update 3

I put a 40 A charge on it (6 cells for 12V) last night for 20 hrs. I was hopefull. I tested it today after the chrger kicked off (max 20 hr cycle) and ........sigh - same voltage!!! No gain whatsoever. How disappoiting.

From what I read now from your posts, either I borrow a higher A charger and hit with 80 amp charge OR disassemble the cells (jumpers off) and test individually each cell for a dead or shorted cell.

Wild you have me intrigued about the shorted cell possibility if bubbling activity right away once charger goes on (they all do). Could they all be shorted? I think I will disassemble and test but how to test for shorted cell and further the remedy? Granted there is a bunch of reading resources out there - the time required to sift through / search coudld not be at worse time really.

John

westbranch · March 2010

Re: Forklift battery salvage attempt

John, can you see if there are any ID numbers/letters on the cases. Did a search and all I can find is 12 v product, no mention of 24 v.

Eric

niel · March 2010

Re: Forklift battery salvage attempt

i wouldn't have charged it for that long for any dead or shorted cells will cause the good cells, if any, to overcharge. if you, can go ahead and check individual cells for their voltage and specific gravity to see which may be good yet.
don't worry about getting a hold of another charger as the one you have did give it the 40a. while you are checking this part of the batteries that you gave a 20hr charge to now put about a 3-4hr charge on the other 6 cells to see if the voltage/sg comes up on any cells.

bluetick · March 2010

Re: Forklift battery salvage attempt

If you split the cells, you should log the voltage/SG reading. In 12 or 24 hours do another reading, After being off the charger for a few hours, levels will change in all the cells but a bad/shorted cell will be outside of the average.

mike95490 · March 2010

Re: Forklift battery salvage attempt

I think a shorted cell, will NOT bubble, but cause the good cells to bubble more. if it's shorted, there is no flow in the electrolyte, it's just plate to plate. At least thats how I define shorted.

bluetick · March 2010

Re: Forklift battery salvage attempt

I can think of 2 types one "open" current will not flow, the other is "closed" or direct short, like a small piece of lead or paste that works like a filiment in a bulb or heater when enough voltage is applied, it heats to the point of boiling the surrounding fluid. This type of short can take days or hours to run down the battery.

It will cause the other cells to charge faster but not boil when a charge is first applied.

wild01 · March 2010

Re: Forklift battery salvage attempt

If the voltage isn't coming up at all, it may be time for EDTA. the reason I said to charge at 80 amps was because if the cells short out (grow trees between the plates) the high amps will melt these trees out. One problem you can run into with a "smart" charger, is that it will detect the short and not give the battery the amps you need to burn the trees out. if you are getting a lot of bubbles though, it's probably just sulfation. the EDTA will fix that, I would consider EDTA a last resort, as it causes the sulfation to build up at the bottom of the cell. (which can cause a short) also, you don't have to split the battery to check the individual cells, just make sure you don't have the battery hooked to any loads and test the individual cells with a multimeter.

also after EDTA it may be necessary to add acid, because the EDTA breaks down the sulfate w/o turning it back to acid.

before you use EDTA, you may try charging the whole bank for a couple hours with the 36 volt charger on it's highest setting, make sure when you do this you remove the fill caps to prevent offgassing pressure from causing an explosion. wear protective clothes and disconnect the charger if the battery becomes hot to the touch.

also as i said before cycle the battery a few times as hard as you can, discharge it as fast as you can and immediately recharge it. for some reason this works very well for forklift batteries.

good luck

edit, you can also try charging 5 cells rather than 6 on the 12 volt setting to overcome the internal resistance, if you don't want to use the 36 volt charger.

Another method to remove trees, is to dead short the battery for a few minutes, but this is a last resort and fairly dangerous.

885kcdtq · June 2010

Re: Forklift battery salvage attempt

I managed to salvage my C&D 510 Ahr bank almost to full.
I put my 3 stage charger on it for literally days/weeks at 40 amps.
Cycled pulse mode numerouse times along the way. They really bounced back after I hooked them up to my XW. I ended up cycling them extra hard without realizing it.. New system and hadn't set it up properly. I ended up discharging them severely till the XW under volted. Charge rate was set high from the factory and I did not realize that till later. They charged at over 100 A for hours before I noticed they had heated to near 30*C (from 20*C @ rest). Shortly after my SGs started climbing.
When I started this, all cells were @ 1-1.5 volts at rest. SG was around 1185-1200. Now all cells are 1260 except 1 which never rises above 1250. $75 salvaged forklift cells paid off I guess.
I wouild still like to see highere SG's but for the price who can complain?
For $40 I would say exercise caution(explosive gasses), and what do you have to lose. A new bank of that size is $8-10,000.
Best of luck.

Forklift battery salvage attempt

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