Reviving 12V Gel cells
 

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

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?
======================
Apply briefly a high current to break the sulfate by charging a high
capacity electrolytic capacitor (10000microFarad) to say 40 -50 V ( or even
higher) and discharge via battery.

The reason for having a 'dead' sealed battery can also be that the battery
has been overcharged resulting in lack of electrolyte.

Some people have been successful to 'revive' an electrolyte starved battery
by getting access to the rubber vent caps ,removing these temporarily and
injecting a minor amount of distilled or de-ionised water with a syringe.

A sealed battery is NOT necessarily a 'gel' type.

There is a lot of useful info on sealed batteries on the Web. Google is
the usual tool for that.
A good site is : http://www.buchmann.ca/

Frank GM0CSZ / KN6WH

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

In article 42e35092$0$29458$5a62ac22@per-qv1-newsreader-
01.iinet.net.au, says...

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?

Sealed lead-acid (not all are "gel" types) can SOMEtimes be
revived. First and foremost: If the battery measures zero volts, don't
even try. Recycle it.

If it shows 10 or so volts, it may have developed a bad cell.
Revival can be attempted, but don't expect miracles.

The best possible method to revive any weak rechargeable battery
is with an electronic battery conditioner, such as those made by Cadex
or Christie. While very expensive if purchased 'new,' used ones often
show up on Greed-Bay, or at ham swap meets. Such a device will often use
a tightly-controlled 'pulse' charge/discharge method, which helps
destroy things like sulfiting without damaging the battery in question.

Happy hunting.


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"

On Sun, 24 Jul 2005 10:46:35 +0100 "Highland Ham"
wrote:

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?

Apply briefly a high current to break the sulfate by charging a high
capacity electrolytic capacitor (10000microFarad) to say 40 -50 V ( or even
higher) and discharge via battery.

That's the "trick" for possibly fixing a shorted NiCad, but it won't
fix a sulfated lead acid cell. Sulfated cells can only be recharged
extremely slowly. They will exhibit a high cell voltage while doing
this, but trying to charge them faster with higher current will only
electrolyze the water in them and damage the plates.

The reason for having a 'dead' sealed battery can also be that the battery
has been overcharged resulting in lack of electrolyte.

Absolutely right! There's no way to charge a lead acid battery that is
dry. You can add water to some, but some are so well sealed that you
have to destroy them to get in there.

Some people have been successful to 'revive' an electrolyte starved battery
by getting access to the rubber vent caps ,removing these temporarily and
injecting a minor amount of distilled or de-ionised water with a syringe.

A sealed battery is NOT necessarily a 'gel' type.

Right, but you can tell a lot by the voltage across the cell while
it's trickle charging. Gel cells, starved lead acid cells, and regular
lead acid cells all share the same chemistry and will show 2-2.4 volts
per cell, NiCads and NiMH are 1.2-1.4V, and Lithium cells run about
3V. Of course none of this works if the cell is dry.

A LOT of these die just by drying out. Injecting a bit of water is a
good idea if you can get in there.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

In article ,
says...

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

Most of the gel cells from UPS type supplies are baked to death! They
have been trickle charged until the gel is now dry paste. I have seen
then so badly over charged that The cases are distorted, and the terminals
are being forced right out of the case due to plate growth.

Probably not worth your time to even attempt. New gel cells are cheap.