Resurrecting rechargeable batteries

[rjv]

Hi..I have a Craftsman's 19.2v drill and the batteries don't charge any more. Does anyone know how to reset them? Reply to [e-mail]. Thanks alot.,

[Rich256]

Most likely a shorted cell. No "reset" is practical. Only cure would be to open the unit and replace the cell.

If the unit is open might be possible to burn away the short but that is a short time cure. I have done it many times with individual cells but they never lasted very long.

To avoid the problem try to avoid total discharge and don't overcharge.

[Mys Terry]

Visa or Mastercard will do it.

[m Ransley]

Nicads are discharged when the tool just slows, over discharging can reverse a cells polarity and is hard on batteries.

[digitalmaster]

sometimes you can charge a cpacitor then discharge it across the battery.do this 4 or 5 times ...sometimes it will let them take a charge.

[lp13-30]

Very interesting hitting the batteries with a capacitor. The two sites give very different information about the voltage used though. Have you ever done this procedure, and if so, exactly what kind, size, etc, capacitor did you use, and what voltage did you charge the cap with? Thanks again for the info. I have a BUNCH of cordless drill batteries to experiment on, and also take apart and rob good cells from-- a pawn shop was moving and getting rid of years of accumulated junk. I bought about

25 or more batteries of all different brands and voltages for either 10 or 15 cents each (I forget which), so I have plenty to experiment with and if I screw one or two up--no big loss. Thanks Larry

[hallerb]

BE CAREFUL! Running even short term high current thru a bad battery can make it explode! I had a friend who used to do this, fortunately he didnt get hurt the cell ruptured away from him.

you must realize stuff has a life expectancy. kinda like a tank of gas it will only go so far.....

your better off replacing the cells or battery. there are companies that rebuild batterys by replacing all the cells, sometimes with higher capacity ones.

I largely avoid battery operated tools for this reason, somehow the battery always seems to die just when I need it the most:(

[C & E]

does rebuilds for less than the cost of new. I haven't used them but have read favorable posts from others.

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[Rich256]

About the only effective way to is do it across a single cell. Burns away the shorting fingers. First you have to determine which cells are shorted. The others in the pack have probably been damaged by overcharging. Once they start to short out it doesn't take long before they short again.

I have even done it by "flicking" a wire from a 12 volt supply across a cell. Gets a big spark and could blow the battery!! Best to devise a way to shield yourself from that possibility.

With all those spare cells you could probably salvage out good cells and rebuild others.