Author Topic: Help with forklift battery  (Read 5876 times)

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Ballyk

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Help with forklift battery
« on: April 19, 2009, 08:46:28 PM »
Hello all. Im new to this home power business. I have a wind turbine and am planning to add solar too. I bought a forklift battery for €50(im in Ireland here). It weighs 1650lbs and was orininally 48volt but I only need 24. It is made up of individual 2volt cells (24 in all). I took the best cells and made up one 24 volt battery and plugged it in to a large charger i borrowed from a friend. this thing can throw out 100 amps. I charged it at a low setting and the next day I had 26volt on my meter. I joined all the cells with flattened 1/2 inch copper pipe screwed on top of the posts. I dont know if its fully charged or not. I have read posts here about "equalisation" etc and I really havent a clue what you are all talking about.


I looked at the rest of the cells and most of them were dry. I washed them out with an EDTA solution and they cleaned up well. I then refilled them with 30% sulphuric and connected them in the same way. Put them on charge and again got 24volts next day. If im lucky I will have 2 big batteries, or blow myself up!!!!


I really need somebody to talk me through setting up these batteries,

How long do I charge them for?

How strong a charge do I put on?

Do they really bubble that much?

will the dry refilled cells come back to life?


I have todat started to log the SG of each cell. None of them are in the right range but I am still getting the voltage. Will this come right and how do I get there.

So many questions but maybe somebody can hold my hand and help me along.


regards to all. Its a great site for the likes of me .

« Last Edit: April 19, 2009, 08:46:28 PM by (unknown) »

kurt

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Re: Help with forklift battery
« Reply #1 on: April 19, 2009, 04:19:29 PM »
your 24v battery should be charged to 28.8-29v wile under charge to be at full charge higher for equalization charge after having been off charge for a few hours and after applying a light load for a minute to remove surface charge it should measure 25.4 to 25.8 something like that depending on battery chemistry you really need to get a good hydrometer with temperature compensation and check the specific gravity of each cell... and compare that to a proper chart...  
« Last Edit: April 19, 2009, 04:19:29 PM by kurt »

wpowokal

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Re: Help with forklift battery
« Reply #2 on: April 19, 2009, 05:53:57 PM »
Ballyk, The maximum rate should be 10% of their rated amp hours, ie for a 1000A/H battery then 100Amp max. This is reduced when the charge comes up, when equalizing which begins occurring above 28 Volts, keep the volts within maximun for any equipment that may be connected (inverter) or not more than 32v if nothing is connected.


Once the batteries are begin freely gassing (about 28.5V), yes they are noisy and no naked flames that's hydrogen being given off. Maintain this state for 5-6 hours, reducing the charge rate (current) to that which will maintain the voltage, if current is not reduced they may overheat.


Specific gravity of each cell will should come closer together over this period. If you have a cheep hydrometer don't get too fussy about what the SG is just that it is as close as possible in all cells, one can not be too pedantic with old cells.


Allan down under

« Last Edit: April 19, 2009, 05:53:57 PM by wpowokal »
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wpowokal

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Re: Help with forklift battery
« Reply #3 on: April 19, 2009, 08:42:42 PM »
http://photovoltaics.sandia.gov/docs/PDF/caploss.pdf


A bit of technical info.


allan down under

« Last Edit: April 19, 2009, 08:42:42 PM by wpowokal »
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Ballyk

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Re: Help with forklift battery
« Reply #4 on: April 20, 2009, 01:44:34 AM »
Thanks lads,

Its 8.45 here now and I'm off down to my shed to try out your advice. I will let you know how I get on if I dont kill myself !! Later then
« Last Edit: April 20, 2009, 01:44:34 AM by Ballyk »

Ungrounded Lightning Rod

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Re: Help with forklift battery
« Reply #5 on: April 20, 2009, 12:43:12 PM »
What equalizing is about:


The cells in a battery have slightly different amounts of leakage.  Eventually, if you only do "normal" charging, you end up in a situation where some cells are fully charged while others are well below full charge.


You have to stop discharging when the lowest cell is discharged (or, to avoid damage, is still at the minimum partial-charge state you're prepared to accept.)  So your minimum charge is limited by the least-charged cells, your maximum charge (under ordinary charging) by the most-charged cells, and the overall capacity is decreased by the difference in state-of-charge between the least- and most-charged cells.  Further, your equipment (or you) may not notice that the voltage is dropping and shut off discharge before you reverse-charge and damage the least-charged cell(s).


To fix this you periodically do an "equalizing" charge.  This consists of raising the voltage enough to force current through the fully-charged cells and bring the less-charged cells up to full charge.  When you do this the current through the fully-charged cells electrolyzes water into hydrogen and oxygen.  This is the "boiling" referred to.  (Some batteries have catalytic caps that recombine the gas into water - IF you do it slowly enough for the catalyset to keep up.)


You have to be careful with equalizing charges for a number of reasons (which you can look up now that you have the basic concept.)  But done properly, and done regularly but not too often, they're good for the battery.

« Last Edit: April 20, 2009, 12:43:12 PM by Ungrounded Lightning Rod »

Ballyk

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Re: Help with forklift battery
« Reply #6 on: April 20, 2009, 03:54:56 PM »
Hello all again.

Ive just come home from a course Im doing and its 22:45pm. I put the charger on this morning at 8:45am and turned it to 50amps. Within an hour or so the batteries were bubbling but I dont think I really achieved what you were all saying.

The highest voltage I measured was 26.9. Each cell was at 2.19 to 2.22. The electrolite was bubbling away very nicely.When I took the charger off it I measured 25.9 volts. The cells were warm to touch and my copper pipe cell joiners were also warm but not "hot". The amp meter on the charger had dropped to 35amps too. Id say I pulled a huge amount of juice from the grid which will probably give me a heart attack when I get the bill. Never mind I can use the battery as a defib!!


I dont know if I have recharged the dry cells or exactly what I have done. Its still bubbling away down in the shed and Im wrecked and off to bed. I will check it again in the morning and post later. What exactly should I be reading in the morning and does the beast need any more special treatment?

regards to all.

« Last Edit: April 20, 2009, 03:54:56 PM by Ballyk »

wpowokal

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Re: Help with forklift battery
« Reply #7 on: April 20, 2009, 05:36:09 PM »
Keep going you are heading in the right direction, keep an eye on electrolyte level, I don't remember you stating battery amp hour rating but, this progress may take a few days.


You are probably drawing about 1.5Kw/h from the grid, so relax on that.


allan down under

« Last Edit: April 20, 2009, 05:36:09 PM by wpowokal »
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Ballyk

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Re: Help with forklift battery
« Reply #8 on: April 21, 2009, 03:29:56 PM »
Hello all,

I put this battery on a high charge again today from 9am to 10:10pm and this is what I observed. The highest charge I saw was 27.1 volts. Each cell registered between 2.19 and 2.90 volts. The SG in all cells rose quite a bit and are nearly in the green on my hydrometer even though I dont know how accurate it is. When I turned the charger off tonight it was showing 28amps and the voltage at the terminals showed 26.9volts. Heating up was the same as yesterday, warm but not hot.I think I am doing OK but I dont really know. will I go for a third day tomorrow or will I do more harm that good. I read about a desulfator called the battery life saver today.It seems to promise a lot. What do you think of this. its a BLS12/24. Google it and see what you think.I have the other half of this battery to do next so maybe as a comparison I might try the desulfator and record the results.Maybe I can post a picture of this battery as the amp hour rating is somewhat of a mystery to me. maybe somebody can have a guess at it.

I assume "Alan down under" is actually down under. If that the case what do you think about the 14 Irish on the lions !!!

Regards

Ballyk
« Last Edit: April 21, 2009, 03:29:56 PM by Ballyk »

Flux

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Re: Help with forklift battery
« Reply #9 on: April 21, 2009, 03:58:34 PM »
 "Each cell registered between 2.19 and 2.90 volts. "


You have lot of variation. The ones at 2.9v will be gassing violently.


If you have 2 halves of the battery it may pay you to try to get similar cells in each bank. Otherwise you may have to deal with cells individually.


Perhaps if you keep going as you are doing they may eventually equalise, especially if you cycle them with load as well but you will have to drop the charging current to keep the high voltage cells from boiling and you will not be forcing the low ones up much. The low ones may be sulphated and may never recover properly. That is why I suggest you get one bank of good cells and get the others in the other bank. The good bank will do most of your work and the poor ones may make some sort of a recovery if worked hard.


In the end you may find that you have to abandon the worst cells but if you can get one good bank you should manage. Its sods law that you will probably never end up with the right number of good cells for one decent bank.


Depends how long they were dry but you may never get a full recovery. Difficult to deal with unmatched cells in one bank and you may have to do some occasional individual charging if they are very unmatched.


It is early days yet so things may settle down with a few charge /discharge cycles and more equalising.


I have not had that much luck with EDTA but it may help. I have no faith at all in desulphators but some do . If you have faith they may work for you or at least you may persist with equalising longer than you otherwise would have and it may do the trick.


Flux

« Last Edit: April 21, 2009, 03:58:34 PM by Flux »

Ungrounded Lightning Rod

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Re: Help with forklift battery
« Reply #10 on: April 21, 2009, 07:17:25 PM »
EDTA works by dissolving the sulphate and removing it from the plates forever.  If the sulphation is not too bad you end up with a working (but smaller) cell.  If it is very bad the plate comes apart when the crystals are removed, destroying the cell.


You want a working BATTERY.  So shrinking some of the cells by removing the sulphate with EDTA is a last resort thing to do:  While it may give you working cells they'll be of varying capacities, which makes the battery inherently unequalized and causes continuing problems.  Even if there's some sulphation I'd try to get it broken down and the lead back into service by cycling the batteries a few times before trying EDTA on any cells that are fouled up.


It sounds like you have combined cells from batteries that were in different states of charge.  So I'd keep trying to equalize them for another day or so - after adding water to any cells that have gotten low and maybe at a lower charging rate - before deciding that the variation indicates anything wrong with the cells themselves.  The specific gravity coming up in all the weaker cells in your "good" battery, and still rising, sounds like you're getting near the end of an equalization of wildly unequally charged cells rather than sulfated cells.


(Now maybe the HIGH ones have a sulphation problem.  But see if they stay high if you turn off the charging current and discharge 'em a tad.  Sulphated cells show high voltage on charge and low on discharge because of the high-resistance sulphate coating on the plates.)

« Last Edit: April 21, 2009, 07:17:25 PM by Ungrounded Lightning Rod »

bob g

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Re: Help with forklift battery
« Reply #11 on: April 22, 2009, 01:02:16 AM »
i didn't really want a piece of this one, mainly because i end up pissing someone off, and that i don't enjoy at all.


some thoughts on your situation


the thinking of trying to match up the cells to get some sort of sets going to work

with is a good one, even if you have to break them down into 6volt strings if you have a charger that works at 6volts nominal.


forget the desulfators, and forget the edta until you have exhausted all other conventional means, i can go on about both but it really isn't necessary to do so.


your going to need to get the cells voltage up to around 15 plus volts for a while

and your going to need a decent hydrometer that is temp compensated, charge them for hours if not days until you get the specific gravity to come up on each of the cells to near what they came with, ~1260 or so. this might take many hours, and you will want to keep the water level checked and filled as necessary and keep the cell temps below about 110 degree F. if they get hot, let em rest and cool then get back after them again.


at some point you will have several cells that are going to recover just fine, so match them up in strings, there will likely be a few that are just ornery and will require more work.


those that require more work


drain the electrolyte and refill with distilled water, and connect to a charger

the specific gravity will be 1000 because it is water, and it may take several more days at 15 or 16volts to get the crytalline sulfate to break down, but over time it will as evidenced by a raise in the specific gravity, bear in mind the specific gravity will never come up to 1260 because it is mostly just water, but it will rise at some point and plateau.


once these cells have come up as far as they are going to, drain the water and refill with fresh electrolyte, and put em back on the charger for another couple hours at ~13.8 volts

then do a load test, but don't expect a new batteries performance


if after all this, you have a few cells that just don't respond, then go ahead and try your edta or desulfator or whatever poison you like, odds are nothing will bring them back to life again.


also it is fair to note that once a battery degrades to about 80% capacity fully charged of its new condition it may still look like a good deal, but the reality is the battery is on its last legs and it will start going downhill rapidly from then on. so thinking that a 1000amp/hr battery is still a heck of a buy at 80% or 800amp/hrs is flawed thinking, the batteries decline comes on rapidly soon after.


the reason i don't like edta or desulfators is based on the fact that they have never been proven to be more effective than a good equaliztion charge using the proper procedures and enough time, and there is some evidence that one can actually damage an otherwise rechargable battery by chemically altering the plates and the other doing irrepairable damage to the plates by dislodging the cystalline sulation

and allowing it to fall to the bottom where it can never be recoverted leaving the cells specific gravity lower than it should be and with the need of modifying the specific gravity with the addition of more acid. the problem being it is difficult to know how much acid to add to correct the specific gravity if you don't have the cell fully charged.


one last note, that being the copper straps you made of flattened copper pipe

if they are just straight sections and they get warm/hot they will expand in length

which places a lot of unnecessary stress on the terminal posts of the cells. this will either loosen the connections over time or worse damage either the seals/casetop or the lugs internal connections to the plates. so you may want to figure out some method for the copper to flex without stressing things if possible,

if not then i would recommend replacing them with stranded cable.


yes it is expensive, but you will have a sizable investment in those batteries time your through, no sense killing them by stressing the connections.


bob g

« Last Edit: April 22, 2009, 01:02:16 AM by bob g »
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bob g

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Re: Help with forklift battery
« Reply #12 on: April 22, 2009, 01:06:45 AM »
the 15-16 volt charging referenced to was for a 12volt nominal string of course


bob g

« Last Edit: April 22, 2009, 01:06:45 AM by bob g »
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Ballyk

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Re: Help with forklift battery
« Reply #13 on: April 22, 2009, 02:55:22 PM »
Hello again.

Spent another day messing with this battery. Took the advice re solid connectors and have now got lovely flexible cable connections between the cells. The beast is performing strangely today but maybe it is doing well. I took some more readings of voltage and SG on each cell and I will give them below for analysis by anybody who knows more than me please. I will give it another go tomorrow and record the results again. When I finished tonight I saw 24.9 volts. It had peaked at 27.3v today higher than ever before. This was after removing surface charge.

A 2.05v  1250

B 2.05v  1200

C 2.05v  1200

D 2.05v  1225

E 2.07v  1250

F 2.03v  1200

G 2.03v  1225

H 2.07v  1250

I 2.04v  1250

J 2.05v  1200

K 2.05v  1225

L 2.05v  1200


This seems like an improvement on the previous day when cell voltage was all over the place. Am I right? Will I do the same again tomorrow or not?


All and any advice will be appreciated.

Thanks again Ballyk

« Last Edit: April 22, 2009, 02:55:22 PM by Ballyk »

wpowokal

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Re: Help with forklift battery
« Reply #14 on: April 23, 2009, 06:06:24 PM »
I still say you are heading in the right direction and should keep going with all the above advice in mind.


One point about battery volts, a digital multimeter  take very minute current and as such the probes need to be in good contact with the terminal or false readings are given, place the probes firmly on the battery terminal not hard connectors.


allan down under

« Last Edit: April 23, 2009, 06:06:24 PM by wpowokal »
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