On Aug 24, 9:43 am, "Stupendous Man" wrote:
My in-law knows a lot more than most about electical things. He buys old
devices with bad ni-cads, then charges up a huge capacitor with something
about twice the battery's voltage and zaps it. he says half of them come
back as it toasts the sulfate short-circuits.

I use a DC mig welder, set at around 25 volts, to zap my 12V
cordless batts for about three seconds. Works OK.

Dan