Nickel-Cadmium Recharging Question

I just found 4 older nickel-cadmium C batteries made by General Electric, and 2 " RENEWAL" re-USABLE alkaline C batteries by Rayovac. They are probably 8-15 years old.

Despite warnings on the new Energizer charger that I bought yesterday, I put them in and started charging them. Lo and behold they charged up (I only did a partial charge as I was chicken to do more until talking to someone about it) and were usuable in my Mag 2C / LED conversion light. The charger says it charges at 200 ma. The nicad batteries say to charge at 50-100 ma, so I am only at double the dosage. The old Renewal charger I have says it charges at 400ma, so I think I am ok charging the Renewal batteries since it is less of a dosage. I know it may not be the best for the batteries to do it this way but I dont want to spend the money for a nicad charger since I will never buy nicad batteries again. I just want to make sure that this is not too dangerous and that the batteries won't explode. I would appreciate any experts out there that can tell me if I am doing anything highly dangerous.

Hello Cary,

I am not sure how the Renewal batteries terminate the charge. The Energizer charger will be charging for a period of time and may have an over voltage cut out as well. The thing to look for is heat. When your batteries heat up, they are usually close to fully charged.

I have never used the Renewal batteries, so can not comment on how they charge. There should be no problems with the NiCd batteries. NiCd chemistry is very robust and can handle higher charging rates and over charging better than other chemistries. You can charge a NiCd battery on a NiMh charger without problems.

Tom

Charging NiCd at a high amp rate will reduce the life of the cell. And as silverfox stated keep an eye on the temp.Warm batttery is representative of a full charge.If your charger is auto cut off, then chargig at a high rate can trigger a "False-Peak" ie the charger will auto-cut off when the cell is in fact isn't.If this happens then you will end up giving the cell a new memory of what is a full charge and eventually render the cell useless.:thumbsdow

Renewal cell charging in a charger not intended for the renewable alklaline type cells is no different than charging regular alkalines. Unless your charger is designed to reject alkaline batteries, then you run the risk of rupturing the cell and damaging the charger.

I also believe the Renewals are 1.5 volts, and not 1.2 volts. In this case you would need a charger specifically designed to charge to 1.5 volts. Some auch as the Accupower 20 will in fact charge the Accucells (RAM) to 1.5 volts.

When NiCd batteries are fully discharged, they can not be recharged, they form whisker-hair conductors through the electrolyte that self-discharges them as fast as they can be charged.

You can try to force a couple of amps through them for less than a second to try to burn out the whisker-hairs and then charge it them normally at 100mA.

Even if this gets them working, they'll never be as good as they were before.