2V batteries - testing - What's a good voltage?

[paulrogers6]

Dear  All

I have the "chance" to obtain some 2V 600amp ex forklift batteries.  I understand that if buying 12V batteries that one way of quickly testing them is to see if the volateg output is greater than about 10.8V.  Is there a similiar rule of thumb for 2V batteries?

Also once wired together (in series) to form a 12V cell will the trigger voltages for charge regulators, LVD's etc be the same as for a 12V battery say 13.8/10.8V?

Thanks

Paul

[zeusmorg]

 It would be much better to use a good quality hydrometer (glass, temperature compensated) to check individual 2 v batteries.  the first thing  you want to look at is the electrolyte level. then take a reading.  If you do want to use the voltage rule of thumb,you want no less than 1.8v per cell, as to whether you think buying discharged forklift batteries is a good idea, that is your decision, I personally would not pay over current scrap values or not much more.

[Flux]

I tend to agree. Unless you have reason to believe otherwise they are scrap. They may have reached the point where they no longer hold a daily charge or one cell in the string may have failed.

Occasionally some people scrap them on a time basis even if still working and these will be the best ones to get but unless you are in the know you shouldn't be prepared to pay much over scrap price as you may not get much use out of them.

Anything below nominal 2v means they are low and sulphating. Cells with no electrolyte showing will probably not make any reasonable recovery. If there are significant variations in electrolyte level or open circuit volts then you may be on a looser.

It is unusual for decent batteries to be scrapped so don't expect much.

Traction batteries are not the best for any form of float charging, they stand deep cycling better but you will need a lot of top up charge to make up for self discharge so you need a lot of charging capacity compared with things like VRLA. Unless you have a lot of charging current available you may never need any form of charge controller and they are better managed on a manual basis with a good ovrcharge when you can spare it. Get them up to gassing when you can and if you have sufficient charging current gas them until sg doesn't rise after an hour. You can float them then if you want. They will float at about 13.8v but you need much higher voltages to fully charge them.

They are better monitored on sg rather than volts but you will need fairly high charging currents to stir the electrolyte to get good hydrometer readings.

Flux

[paulrogers6]

Hi Guys

Many thanks for the replies.  The units are 25GBP plus delivery (some 200 miles away) so upward of 150GBP for the 6 units needed to bring it up to 12v.  I'm not sure they're scrap (condition is described as second hand but excellent - with uses suggested for Forklifts and/or wind turbines etc) and as such rather expensive to just bin if DOA.

I was concerned that if they were delivered and useless a quick way to check them and return them was required.

By the sounds of it I'm best off giving them a wide berth.  The alternative is some 12v/90AH UPS batteries that are local, meaning I can check them before purchase and return them fairly easily if there's a problem.  They're 40GBP a unit so much more expensive to reach a similiar AH (trying to get as big a bang for my buck as possible).

From you're comments are you suggesting that having got to this sort of (600) AH that a turbine will struggle to properly charge the batteries anyway?

Thanks

Paul

[Flux]

The larger the battery bank the more problems keeping it charged but it all depends on the size of turbine. For traction batteries you may have to get near 60A for a while to get them up quickly. Normal Trojans and similar will have significantly less self discharge and should be fine with a reasonable sized turbine ( 8 to 10ft ) in a reasonable wind area. VRLA/ gell are lower in self discharge but have their own problems.

With large batteries on a small turbine things will probably be ok most of the time but if things get well down in a clam period you may have to resort to some back up charging scheme to get them back up quickly , once you let them sulphate it takes a lot of energy to sort them out.

Poor condition Forklift/ traction may be a challenge with a small mill but at 600AH for most 12v systems it ought to be ok.

Flux

[paulrogers6]

Flux

Again many thanks for the replies.

regards

Paul

[jacobs]

Battery Voltage = Specific Gravity of Electrolyte + 0.84 @ 77 Degrees F.

Example: 1.220 + 0.84 = 2.060 x 6 (Cells) = 12.360 Volts

Example: 1.280 + 0.84 = 2.120 x 6 (Cells) = 12.720 Volts

Some 2 volt batteries have a specific gravity of 1.200 to 1.220 from the factory. If so, there is a label on the top of them stating this.

[Ballyk]

Hello,

Im no expert and dont claim to be but I recently bought 24 cells from a forklift that have been lying in a yard for about 4 months. It has taken a lot of work but I think im getting there. They cost me  about £45. I have had a long discussion runing on these which is posted on this site.

Regards.

Ballyk

[paulrogers6]

Ballyks/Jacobs

Again thanks for the replies.

Jacobs

You state specific gravity's of between 1.22 and 1.28 and voltages between 2.06 and 2.12.  Are these indicative, or are they the sort of voltages/sg's one should expect (at full or empty) charge?

Others have stated that any voltage below 2v is Useless?  Is it therefore safe to assume that any SG below 2.000 - 0.84 = 1.16 is also Useless (based on others' comments I propose to buy a hydrometer if it becomes necessary to test the cells)?

Thanks

Paul

[Madscientist267]

I'd like to add that personally, I would avoid the UPS batteries (unless they were free and/or never used) as UPS systems are notoriously designed with the batteries being the "weakest" components. ie, a UPS typically draws several C, a scenario which is just not conducive to healthy batteries. They tolerate it a few times, but give out rather easily in their intended environment. Once a UPS is 'done' with them, they're not good for much else either.

As bad off as you might end up with the forklift cells, even with sulfation and all, at least they were designed with the idea that they would be delivering their charge over the course of several hours, not minutes. This is a much better scenario IMHO, and would lend to healthier cells in general. Although

Besides, even if they're only capable of delivering 50% of their original design spec, you're still sitting at a pretty 300AH; the (likely sickly) UPS batteries you're describing would only be good for 1/10th that (maybe) if they've seen life as originally intended.

I'd be willing to bet that desulfating a 600AH battery would be a skull numbing concept at best, but worth it if it paid off.

Just something to keep in mind.

Steve