Discharged UPS Batteries

[DanF]

I have a bunch of UPS batteries I've acquired some months ago: 12V 9A. These were fully charged back then, but by time I forgot them in a cabinet and got discharged to around 3V - 4V.

Is there any way to revive / recycle these batteries? A friend of mine who's into electrical stuff said that it's possible, but not every charger is able to charge these.

 

[Markverhyden]

Just get a trickle charger. Something like the below. They have them in autoparts stores around here. Some come 6 and 12 vdc.

http://www.batterystuff.com/battery-chargers/brands/battery-tender/BT-021-0128.html

 

[DanF]

Do you think one that is used to charge car batteries would also work on UPS batteries? Cause otherwise I would just get one that is also good for a car.

 

[Markverhyden]

Do you think one that is used to charge car batteries would also work on UPS batteries? Cause otherwise I would just get one that is also good for a car.

Yes. But you do not want one that does a rapid charge. That outputs a high amperage which will probably damage a small battery like those. That's why I said trickle charger.

 

[DanF]

This one:

http://www.batterystuff.com/battery-products/g3500.html

 

[Mercenary Roadie]

A gel battery that only reads 3 - 4 volts with no load are considered completely discharge and normally can not be recharged. You should also check the date code on the battery, if it's 5 years old or close to it should be replaced.

 

[HFultzjr]

This one:

http://www.batterystuff.com/battery-products/g3500.html

The "trickle" chargers Mark is referring to are generally 1 to 1.5 amps. The one in the link above is 3.5 amps. Might be a bit much for such a small battery. Since you are already dealing with questionable batteries, maybe one like below. If it doesn't work, you won't be out much money. Of course, use with care and keep an eye on it.
http://www.harborfreight.com/automatic-battery-float-charger-42292.html

 

[Candonz]

A trickle charge may work. You could also try charging resting 48 hrs, recharging, resting another 48. Repeat another 2 more times. Then full discharge in a device, recharge again and hopefully use the battery as normal

The following youtube link also is interesting if you are game.

The time spent really does make them beyond economical repair

Good luck. Let me know if you are successful

 

[fencepost]

Lead acid batteries that get down that far and stay down there for a while actually develop crystals, this is called sulfation. You might be able to recover them with the right equipment, but they'll likely never be as good as they were and it's likely to be a headache.

See also: https://en.wikipedia.org/wiki/Lead–acid_battery#Sulfation_and_desulfation

 

[DanF]

Thanks for the explanation. This is definitely not worth the time... as you very well said. I was hoping for some chargers to be able to do this automatically, that would also be able to work on larger batteries (such as car batteries). Otherwise it would not be worth spending the money on them to just use on small batteries like this.

A trickle charge may work. You could also try charging resting 48 hrs, recharging, resting another 48. Repeat another 2 more times. Then full discharge in a device, recharge again and hopefully use the battery as normal

The following youtube link also is interesting if you are game.

The time spent really does make them beyond economical repair

Good luck. Let me know if you are successful

 

[DanF]

Thanks you all. Lesson learnt. Must make sure that, if I'm keeping batteries this long, these should be put into use every now and then.

 

[pastafarian]

They have probably developed internal shorts that will prevent the full capacity from ever being recovered (with normal charging methods).
Recycle and replace.