ATM Battery Renewal

["Jim and Sue Sapp" <jsstars@worldnet.att.net>]

Hi Folks,
     Are there any battery gurus out there? Maybe some of you amateur radio
guys can answer this:
     In the dim reaches of my fading memory, back when all things electrical
were a hobby, instead of a narrow digital field a profession, I had a little
electronics project book that had a circuit called a "zapper" that was
intended to renew old NiCad batteries. If I remember the text correctly, as
NiCads age they lose their ability to recharge due to some hairy stuff that
grows inside them and shorts them out. This zapper circuit would supposedly
apply a large voltage (or current?) to them and "zap" the hairy stuff away.
Does this ring a bell to anyone? I'd like to/need to have that knowledge
again. - Which brings me to my second question:
     I have a 12v gel-cell that seems to have a couple of shorted cells. It
won't take more than about 9 volts of charge anymore. This is one of the
three portable power sources I use to feed my inefficient and power hungry
telescopes in the feild, and would like to renew it somehow without coughing
up the coin to buy a new battery. Do any of you guys know of a way to "zap"
a gel-cell back to health?

- Jim