Battery Reviatliser

[stuee]

Hi.
I have so many poor rechargeable batteries from drills to and emergency light.

I have been messing the zapping thing and got one 18v drill battery working a bit better by hooking 2 car batteries together and zapping with 24v evey couple of minutes for 2 seconds.

I would like to make an automated system though so i can leave on for a few hours.

Please dont tell me about exploding batteries etc, i know the risk but if i can revitalise 2 drill batteries thats saved me $150 and the emergency light battery ($110)

I was thinking of a 555 timer circuit hooked to a car 12v relay as they can take 30A, i was hoping to have a potentiometer so i can adjust the timing, like 1sec every 3 mins or 2 secs every 5 mins and so on.
The voltage to the relay > battery will be based on the input power to the relay.

Any schematics appreciated or assistance

 

[MikeMl]

Dont bother. Zapping a NiCad battery with a high current pulse will vaporize the shorting dendrite, but the fix is not permanent. Because there is a hole in the double layer, the dendrite will grow back within a couple of charge cycles...

 

[dr pepper]

Right over my head there.
I agree recovery will be short term.
Doing this manually if you really must will be a lot safer, leaving something like this unattended isnt good.
I have managed to get some life back into a lead acid battery using a controversial desulphator, however nicads and nimh's are not as recoverable.

 

[audioguru]

I used to zap Ni-Cad cells but the "fix" did not last long. Ni-MH cells do not have that problem and also do not have the problem with memory like Ni-Cad but the Ni-MH cells get weaker and weaker and last only about 5 years.

I found a portable vacuum cleaner in the garbage. Of course its Ni-Cad battery (six cells a little smaller than C size for 7.2V) is shorted so I replaced the cells with two series-parallel sets of 18650 Lithium-Ion cells from an old laptop and it runs like new.