Old forklift batteries

[Simen]

I've finally got hold on some old forklift batteries, but i'm in doubt on the useability of them.

There is a total of 36 cells in 3 banks at 24v. Two of the banks are rated 330A/5h and the third are rated 240A/5h.

One of the 330A/5h banks have little or no water in the cells, and measures only 0.1v-0.3v/cell. I have very little hope for these.

The other one was a bit low on water, but not too bad. Each cell measured around 0.6v

I'm more optimistic about the 'small' bank at 240A/5h. Only a little water was missing; the level was just at the top edge og the plates, and each cell measured around 0.9v-1.1v. So far i've lent my efforts on this one.

Also, i got a 24v/40A charger with the bargain. I'm a bit dubious about the intelligence of the charger, for so far, it seems it's timer-based, and have no maintenace charge.

Back to the smaller bank.

I've run 3 charging-cycles so far, and started the 4'th just a couple of hours ago. The first lasted 4hrs, and had a charging amp that gradually raised from 1A to 6A.

The second lasted only 2hrs, but charged steady at 9A.

The third lasted 8hrs, and charged steady at 18A. After this, the cells had a voltage at 2.0v-2.1v, and the gravity had just raised from 'nothing' to 1.110-1.115.

As said, i started a fourth charging cycle a couple of hours ago, and the charging amp started at 15A, and the cells started to gas immediately.

On the positive side; all cells come with Aquamatic caps, so all i need to do, is to attach a container with water, and the cells will never run dry again.

Images of batteries here.

[thirteen]

you should be able to use the information on the batteries to find out there estimated age. That would give you an idea of the life left in them with good care they may last several years. The companies might be able to give you some help with the batteries to extend there life. They are to me worth charging and seeing what you can get from them. It will only take time and you should be able to at least get salavge from them. Becasue of there (unknown) age they will never be 100% but defenatly worth the try. Unless totally abused to there death they should come back and you will have a system that will need some extra maintence for like anything the older you get the more maintence they will need. Good luck

[Simen]

I haven't found much info on the net except varying info for similar cells by the same DIN standard (3pzs240)

I've charged the 240Ah bank as much as it can hold now i think. the specific gravity are as uniform from cell to cell as it can get on a bank of unknown age and handling (i think it's from '03), and lies at 1.260-1.270.

Now i'm going to start charging the first of the two 330Ah banks... (the one with cellvoltages at 0.6v...)

[Simen]

Now i've charged one of the 330Ah banks a total of 20hours at a steady 20A; it's a lot of gassing activity, but i can't get the specific gravity to get higher than around 1.150...

The guy i got this from said it was low on water, so he had topped it up with quite a bit... Is there a possibility that the 'missing' waterlevel has been spilled out (not evaporated over time), and so the total acid level is now too low?

Should i continue to charge the bank? Or can/should i replace some of the waterlevel with fresh acid? (20hrs x 20A... Should have been added 400Ah worth of power there...)

[dnix71]

If one started gassing immediately, it has shorted cells. I work in a warehouse with electric lifts. A decent set of 24v cells is a couple of $thousand and up. A set for our Raymond would be about $16k.

People don't give away free money, so i doubt your batteries are usable as is. Your best bet is to load test each cell and get rid of the shorted cells. Build a stack with the good ones. There are battery rebuilders who do that for a living. The cost of batteries that size is so high and cost of legal disposal of lead and acid makes salvage pay.

Forklift batteries only last about 4 years in regular service anyway. If they have been left discharged then the plates sulfate just like a car battery.

[Simen]

Thanks for the heads up...

I'm afraid you're right; i've left the 240Ah bank unloaded for a couple of days after charging, and the voltage has been steady at 25,3v. I've just rewired the bank, so it's now at 12,65v. I have connected a small 12v inverter to the bank with a 60W bulb as a load, and after 1/2hour, the voltage is at 12,25v...

Doesn't sound good, does it? :?

Or could this bank come to some useable life again by discharge it and recharge it a couple of times?

The charger i use, is a Jungheinrich Timetronic 24v, 40A charger. It has no maintenance charging, and no equalizing charge; just a timerbased charging with a schedule that i've yet to figure out... (Can't find any info for the charger on the net... )

I've almost given up the 330Ah banks. One of them has an unloaded voltage at 12,45v after days of charging at 20A, allthough all cells are at same voltage.

The other 330Ah bank had 2 dead cells, and several poor ones. The cells are so uneven, that i doesn't think i can put together a 12v bank...

[Simen]

Forgot to mention; those 12,25v on the 240Ah bank is under load, and is actually 12,35v (The battery in my multimeter was flat when i first measured... )

Now, after 4hrs with the 60W load (Measured: 5,43A), the voltage is still at 12,35v. Maybe there is some juice left after all

[Simen]

A small update.

14.5hrs and the voltage has fallen from 12.35v to 12.27v with the 60W load. (plus 7.5W for the inverter itself.)

I think i'll keep this bank. Even if it died now after drawing 80A total, it'll have its uses...

[dnix71]

Equalizing is just overcharging a little so you cook off some of the water in the stronger cells. Once all of the cells are gassing, you have reached a full charge.

After equalizing, you add water to level all the cells off to the same height.

You always add water after charging and while it's still warm. If the cells have exposed plates, you can add just enough to cover the plates, then charge. If you add water before charging you risk an overflow since charging expands the electrolyte volume by heating it and introducing gas bubbles.

[SteveCH]

You are doing all the right stuff. I bought a new set of forklift batteries 12 yr. ago [brand new] from a co. that sells them [brand of mine: C and D]. My set is 12 v. And they've done well here on pv charge, though the co. warned me they didn't think it would work out. It has.

They told me that these battery banks are used hard [duh] on the trucks, they are used right down to pretty much dead during a shift, then connected to rapid chargers for overnight charging. Every day. All the way up, all the way down. The guy there told me that under those circumstances, the banks usually last no more than six yr., talking here about full-time warehouse or loading dock op's. He didn't think that a pv system as I described to him would be powerful enough to charge them back up. Of course, I don't let them get very low in charge, and it's worked fine.

The upshot of this is that your batteries have almost certainly been used REAL hard and drained each shift, then jolted back up to full charge. They might not ever really be a good, strong bank. But nothing wrong with trying. Let us know how they work out. [And they may give you some life when treated more gently than in a factory/warehouse deal.]

[Simen]

Water filling is no problem on these cells.

As mentioned before, these cells have Aquamatic plugs, similar to these:

http://www.hawkerpowersource.com/products/accessories.htm

Though, mine are the previous generation, without the hole for measuring the specific gravity; there is a small hole with a plug in the corner of each cell for that purpose.

[Simen]

Now it's 8 in the morning here in Norway; the load has been on for 22hrs, and the bank are down to 12.22v.

Should i let the load stay on until the voltage are down to 11.9v? (The inverter i'm using, will shutdown by itself at 10.5v) In other words: when should i consider the bank 'empty'?

[dnix71]

The plates will hard sulfate if the voltage stays below 12.2 for long.

Forklift batteries are made to be fully charged each day, so don't run yours down and leave them.

Discharged to 12.3v should be low enough for a safe load test.

[Simen]

I ran the first testload for 24 hrs, and ended on 12,19v with the 60W+ load.

Now i've recharged the bank and connected 2 car headlamps at 55W each; total 110W, and ran the load at 15hrs. The voltage started at 12,75v and fell slowly down to 12,20v during the 15hrs.

Under the first testload at 60W, the voltage started at 12,65v, and fell to 12,35v rather quickly (1/2hour), so i think the bank are getting healthier now...

I might run a third 'wakeup' cycle, to see if i can get it revitialized a bit more...

As i now have some storage, it's time to get my windgen project running...