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Author Topic: reconditioning forklift batteries,  (Read 10281 times)
biff
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« on: June 14, 2009, 11:41:06 AM »

hello all,
         i recently bought a few hawker 48voltx750ah forklift batteries,i noticed that one was a bit rough and had filled up with water,flooding the cells,also what lookes like rusty scum was staining the cell tops.there is still voltage,each cell has 1.1volt at least,i stippped out the tank and cleaned off the tops of the cells,in doing so,it occured to me that perhaps it might be possible to recondition these cells. the banks are hawker "perfect plus" and only about 4 years old.perhaps there is some one out there who can set me in the right direction.
  also,, for a good 18 months now we have been getting a good performance from our 20 piece x 120volt powersafe battery bank.each 105ah x 12volt.
   we have been able to run the house,microwve,toaster,tellys,pcs,all the lights,we decided to install a new washing machine,2050watt maximum it said on the tin,so with the arrival of the first force 6 we gave it a go and watched the heater(hottest wash) slowely but surely eat into the reserve. the second wash was a degree down and not quite as sore on the juice, everything seemed to be ok and then a few days later (without washing machine but normal duties)still with good wind we noticed the voltage dropping,we had our first battery casulty,it was quickly replaced and we are hoping now that everything will be ok.
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biff
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« Reply #1 on: June 14, 2009, 11:32:17 PM »

does anyone have a link to a site where i can get such information on forklift batteries, banghead
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Justme
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« Reply #2 on: June 14, 2009, 11:42:19 PM »

Very very few people recon batteries due to the dangers posed by doing so.

1.1 volts per cell (thats like a 12v batt reading 6.6v when you should stop using it at 12.2v) is seriously low, so low I would consider them duff unless very lucky.

I would give them a good long charge (say a week dep on how big the MAINS charger is) with no usage during charging. Then leave for a day. Then test each cells voltage & SG reading. Then I would decided if there was a problem. I would also run a Equilisation charge (a controlled over charge using higher than normal voltages).


Justme
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« Reply #3 on: June 15, 2009, 12:05:30 PM »

I have had some limited sucess reconditioning a fork lift battery by adding EDTA to each cell. It's tricky to find but the photographic industry uses it and there often 100g packs on ebay.

I used tetra sodium EDTA, dissolved 100g in 600ml distilled water and then added 10ml's of this to each 450Ah cell.

After about 1 month the SG's were noticably better but still not "like new".

Timbo
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biff
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« Reply #4 on: June 15, 2009, 08:05:14 PM »

thank you both for your replies,
          yes the cells on one bank were particularly low,both battery pack were commissioned into service 4 years ago,brand new,the forklift its self became scrap because it never was allowed a service from the makers,then the whole plant was allowed to go to loss after christmas,this particular german forklift had two packs,"perfect plus" by hawker and one of them is perfect,the one i am refering to had its positive pole ripped out and thats the one that is so low.i bought the charger(like new) as well,so far i have devided the low bank into 2 x 24s and put one on my 500watt x 24 volt turbine,it registered about 4 volts on the controller,however it has been steadily creeping up the clock this past 24 hours.at this rate it will take a month to fill it but the weather is calm and wind speed low.it would be nice to think i could save them,
     thank you timbo,i will try that.these cells are 750ah so its just a question of working it out to scale? these cells are very fresh looking when i cleaned them up,the only thing wrong is that they are so heavy to work with.i will let you both know how i get on.
                    biff.
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« Reply #5 on: June 15, 2009, 08:58:18 PM »

Hi Biff,

I must say that your battery sounds to be in a very bad way indeed and I am not very optimistic about it. My Forklift batteries were mostly reading 1225-1275 SG after a night on the charger, 2.2-2.3V DC per cell. The bad 1150 cells were improved to 1250-1275 by the EDTA, even then, a nominal 450Ah battery was actually no better than 200Ah in practice.

There are quite a few links on the web about reconditioning lead acid batteries you just have to muck about with the search words in google! there is a high frequency current pulser which you can make that also allegedly helps

My brother who is a PhD chemist says the problem is to get the lead sulphate off the plates in the presence of sulphuric acid and said that if I could drain the cells, wash well, then it would be easier to get rid of the sulphate with EDTA (or other more easily available chemicals)........problem is, that means messing about with gallons of nasty acid, not to mention polluting the ground with lead from the wash.

Good luck and be very careful!!!

Timbo
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biff
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« Reply #6 on: June 16, 2009, 05:37:42 PM »

today we had a decent force 5 ,, not forcast,the lazy 500 wattx 24 volt decided to work and get on with the job of trying to charge the low battery pack,after a few hours the voltage meter on the controller began to shoot up to the top of the clock and a harsh clicking could be heard every few seconds,i assumed there was not enough power in the batteries to trigger the dump load  and the brake so the relay was stuttering trying to make up its mind what to do,i used the voltmeter because the controller stopped registering at 30 volts and lo and behold there is 36 volts being rammed into the old cells,i let it hammer away and every so often when there is a lull i find the static voltage about 12volt,a big improvement from this morning,which was about 4 volt.the chances of this lot being any good are slim but you never know untill you try.i intend to take a reading tomorrow of each cell and any that are unduly suspect i will replace from the other half of the 48v pack,maybe ,just maybe ,i might have a decent 24v pack out of it.
        i can well imaging that reconditioning forklift batteries would be a specialised job,however that would be all the more reason for me to investigate it properly,with proper facilities and a proper method of recycling the acid mix it could be made to work.,even transporting the packs is a specialised job. no body seems to fancy the job,i have met a lot of people so far in my inquiries and there is this general opinion of how dangerous it is to work with these batteries.i believe once the rules are estabilished,it can be a lot safer than many other jobs. you never know. and yes, i will be carefull.
                                       biff.
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« Reply #7 on: June 16, 2009, 06:08:55 PM »

If you have mains available then put a mains charger on it & forget the wind turbine for now. Its never going to charge long & hard enough to have any chance of equilising those cells. Even the mains charger is going to need DAYS & DAYS to have any hope of doing so. Any thing else is a waste of time. The numbers you quote point to a completely shot set up that a wind turbine is never going to sort out if its actualy possible at all.

Justme
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« Reply #8 on: June 16, 2009, 10:10:21 PM »

hi justme,
         i guess your right,however we have a force 7 blowing up tonight,and i  might let it run a little longer,the voltage it steadily creeping up but like you say it will take for ages.we never applied for the mains even though it passes our front driveway.we have a 5kva,approx4kw geni and i will hook that up when i get my hands on a 24 volt charger,the good thing is that we are not really dependant on the lazy 500watt turbine,it normally runs the small tools in my workshop.the house is run of our main turbine,2kw.
              biff.
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« Reply #9 on: June 16, 2009, 11:24:49 PM »

If, No I mean AS your battery bank is 100% flat you need to recharge using about 43,000wh's
(48v x 750amph = 36000whs plus charging losses of normaly 30% ish but in your case I allowed 50% but likely to be much much more)

Your 500w unit will have to be screaming its pants off for over 86 hours solidly as an absolute minimum.

Ah just spotted you split it into two x 24v units, just half the above numbers.
The controller clicking is it reaching its cut off / dump voltage but as soon as it cuts off the voltage is dropping to lower than the cut off so its cutting back in again. Until it can hold the voltage higher whilst under load it wont stay lock in to dump mode. How many amps are you seeing on the meter?

Justme
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« Reply #10 on: June 17, 2009, 03:13:40 PM »

about 3 to 4 amps max,it was stationary this morning and a quick check revealed that the voltage had crept up,somehwere around 10volts on the meter,
 this particulat 500watt turbine has a very big stator diameter,in fact it is the same diameter as the 2kw and it take a bit to push it along,however it has a very powerfull pulse and fills the clock at quite a low speed,i intended to fit it with the one 1kw blades,same shaft on the 3 models,same hub,and nose cone.glad i did not do it.we have force 8 due this evening so there is going to be a bit more buzzing and clicking in my workshop.
         i already know that this turbine can keep a 750ah x 24 volt battery well up because that is the set up for my workshop before i switched over to the low batts,it did occur to me to join my good full pack to the low pack at the controller and let them level out,i still have that option but i will wait for a few days and see how it does.
     at the moment the 2kw is charging about 80 percent capacity,the 500watt it trundling around happily,but charging comfortably,every so often it takes off and then remembers its lazy.i should have a good idea how well it is doing after today,
                        biff
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« Reply #11 on: June 17, 2009, 05:37:28 PM »

got fed up with the clicking and decided to put low batts on the intensive care mode,so hooked up my good 24v x 750ah to back of controller and waited for the fizzing to begin, no fizzing as yet but clicking has disappeared and voltage is reading 28v on the controller and 25v on the low batts,so the poor dears must be sucking it up,i will give them a few hours and then remove the intensive care and hopefully they will make it on their own chocolateteapot,i could be very very very wrong.its a good evening for the business,the wind is keen to comply.
                     biff,
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« Reply #12 on: June 18, 2009, 09:47:35 AM »

took the poor relations off the charge last night,wanted to keep my good bank well topped up in the storm,checked the low batts voltage this morning,its just about 14,this is after sitting quiet since 1am this morning, put the lot back on charge plus the good full bank,the leads are 64 strand,so nothing is going to happen quickly, the 2kw is on max,blades almost out of sight,driving halogen fires,and topping up reserve batts,the lazy 500 trundles along quiet happily in the storm not at all bothered by the gusts,,will check voltage this evening,
                              biff. bike
     
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« Reply #13 on: June 19, 2009, 10:18:09 PM »

things not looking good,its taking forever to reach any kind of charge,i swopped over controllers today and hopefull this one will send it up a bit quicker,  i took the low life off the charge at dinner time.it was 20volts,,let it sit till 7pm and it had dropped back to 16volts,so sadly it looks like i am flogging a dead horse  banghead,gonna let it sit overnight and souse out the cells tomorrow.then swop over the low cell and start again, thankfully i am not in a rush and the wind is helpfull.
                biff
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« Reply #14 on: June 19, 2009, 11:04:48 PM »

Not looking good for it but then you are trying to fill a leaking swimming pool with a teaspoon.

You need a constant controllable charge source to have any chance at all.

Your 500watt turbine at 24v is only 20 odd amps & you really need at least 75amps for a 10C rate.
You are charging at less than 37C rate. My own charge rate is 12C.

(just in case you dont know the C rate is an expression of the charge rate as a fraction of battery capacity. The accepted norm is between 10C & 20C)

Justme

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Navitron solar thermal system
30 x 58mm panel 259L TS
1200watts solar 120vdc
FX80 Solar controller
Victron 12v 3000w 120a
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24 x 2v cells 700amp/h 5C
Total bank 4350 amp/h 5C
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