Recovered NiCads

[auplater]

Originally posted by soongsc
I used to just charge 70V or so caps up, and discharge it though the Ni-Cd batteries. Also tried to build a circuit to do it, but the swich kept fusing short. There used to be an article "Zapp new life into Ni-CD batteries" in Radio Electronics.

After a few discharges, the voltage will go up, and you can put it into a charger to charge it.

I tried that method several times... didn't work... then tried the AC WELDER method wherein you ZAP the bejeebers out of the critters with a welding arc , , still no luck...

These experiments are what led me to the method above... brought back the same nicads under more controlled conditions... being an electrochemist, I pretty much can visualize what's occurring inside the batteries, since I've actually built some from scratch...

John L.

[soongsc]

Originally posted by auplater


I tried that method several times... didn't work... then tried the AC WELDER method wherein you ZAP the bejeebers out of the critters with a welding arc , , still no luck...

These experiments are what led me to the method above... brought back the same nicads under more controlled conditions... being an electrochemist, I pretty much can visualize what's occurring inside the batteries, since I've actually built some from scratch...

John L.

It seemed to work with most of the Ni-CD bateries that I zapped. The value of the caps were around 10000uF. But I do wonder whether the Ni-MH can be treated like that?

[auplater]

Originally posted by soongsc

It seemed to work with most of the Ni-CD bateries that I zapped. The value of the caps were around 10000uF. But I do wonder whether the Ni-MH can be treated like that?

I doubt that Ni-MH will respond, because the failure mode is different, i.e, there is no metal per se at the anode when charged, just a hydride. I believe that since metal is formed upon discharge at the anode, the mechanism precludes whisker growth, as hydrides don't grow as whiskers the way cadmium does in a nicad upon recharge.

John L.