Hello Richard,

If they are 0 volts, recycle them, not worth the effort
to try to bring them back. They may have an open cell
overcharged or had a surge in the ups.

Most hamfests have used batteries available with
plenty of life left in them. We swap out our
batteries after three years normal use in our
small and large ups systems (data center).

Not all sealed lead acid batteries are gel cells.
GelCell was a trademark of Johnson Controls
and my still be so.
Any other sla type is absorbed electrolyte or
paste. There is the absorbed glass mat,
fiberglass keeps the electrolyte close to the plates.




Richard wrote:

Dear all

I am sure this has been posted before, but I cant recall the response.
I have several 12V gel cells out of UPS's which are dead.
Apparently they can be revived by desulfating them - any ideas on the
way to do this?

Thanks
Richard