bring nicads back to life

[lokeycmos]

i have a 9.6v nicad battery pack for my cordless drill. it only holds a charge for a couple minutes. i have to constantly keep it on the charger so its ready when i need it. i read that these can be shocked back to life. could someone please explain how this works and will i be able to get it to hold a charge for a lot longer? thank you

 

[audioguru]

An old Ni-Cad cell grows metal whiskers inside that shorts it. These whiskers can be blown out by connecting a charged big capacitor to the battery. But then other growing whiskers will soon short the cell.

Your problem is different. Maybe your battery has been over-charged too much or over-discharged too much or too deep and is now not useable.

 

[JimB]

These whiskers can be blown out by connecting a charged big capacitor to the battery.

I have done that, I also have used a 12v battery to blow the whiskers out of a 1.2v NiCd cell.
(WARNING - things got very hot very quickly. Don't come crying to me if you do it and it goes bang).

Having said all that, the resurected NiCd cells did not last very long.
There is only one real fix...


... buy some new ones, preferably NiMH which will probably have greater capacity for the same physical size.

JimB

 

[bountyhunter]

One or more cells probably got "reversed" at deep discharge and are now hosed.