Non flashlight battery question

[Wildcat]

I have some 12V 7ah sealed lead acid batteries. when i hook my charger up to them i get a "fault".

is there any way to bring them back to life or are they headed for the recycle bin?

thanks

 

[Mr Happy]

Some questions that may help to provide a better answer:

What was the voltage of the batteries before you started to charge them?

What is the age and history of the batteries? Have they been stored for a long time? Have they been stored in a discharged state?

 

[Wildcat]

Some questions that may help to provide a better answer:

What was the voltage of the batteries before you started to charge them?

What is the age and history of the batteries? Have they been stored for a long time? Have they been stored in a discharged state?

I didn't check the voltage before trying to charge them. they are APC backup power supply batteries. they have been stored in the ups can, unplugged for about 3 years. the unit started beeping that the batteries needed to be replaced.

 

[Mr Happy]

unplugged for about 3 years

Does this mean unpowered and uncharged? This could be your problem. I believe lead acid batteries need to be stored fully charged, preferably connected to a float charger. Lead acid batteries love to be on continuous float charge, but hate to be in a discharged condition. I understand prolonged discharge leads to sulfation of the plates, which in an SLA is an irreversible form of damage. Even a temporary discharge close to empty will shorten the life of most SLA batteries.

 

[Kremer]

Check the voltage on the terminals, most chargers will reject batteries below a certain voltage, there are a few dumb chargers that will slowly over the course of several days bring up the voltage to the range where a multistage charger will work and kick in to bring the jar all the way up to 13.6 or so.

I'll tell you now that if they've been sitting untouched for 3 years they are probably not going to have any useable capacity, they are probably sulphated horribly, if not shorted. Our battery people at work reccommend to top off/float SLA's for at least a couple days every 6 months if they are in storage and junk them if they sit for a year.