Mark,

Fifteen years ago I bought a Craftsman  14.4 volt drill set at a garage sale for $10.00

Both batteries were completely dead.

I intended to go and buy new batteries but the $80. was a bit much.

I read somewhere on the internet about zapping NiCad batteries with a welder

that would put enough life in them that they would then be able to recharged.

I took the batteries to the shop, zapped them and put them into the charger and fifteen years later they still work fine.

About the same time my son worked in a shop that had 30 NiCad batteries sitting the the " disposal bin " because they were all dead.

He brought then to me and all of them were zapped and recharged. They gave him the drills too.

Being a film maker he used a lot of them for night lights that he made up.He had lots of power for a long time.

So yes it works, but only for Nicad NOT  Lithium.

The theory is that the cells have produced "crystals" within themselves and therefore short themselves out.

By zapping them you break down these crystals and the cells will then again take a charge and continue to work again.

I also tried a method a young kid on the internet did. He  put the NiCadd battery in it's charger and pugged and unplugged it

in a wall receptacle multiple (a lot) and it gave the battery enough life to charge it fully.

I've tried that as well plugging and unplugging took 10 or 15 minutes, but it did work.

The idea is to get some life into it to get them to charge.

So there you go Mark, from someone who did it.

-G