Rejuvenating Nicad batteries.

[PaulUK]

I mentioned the 700mah phone batteries, well today I zapped them on the battery charger on 6v, went up to 6amps about 20 times,only briefly touching the terminal, then gave a couple more at 12v,prior to this they would not power the display on the handset but after the display lit.I have not got a tester yet so had to use a charger that then showed good, so have left them on charge for 10hrs or so and see how long they last when being used.
I think I will have to clamp some metal to the contacts on the drill battery as the contacts are really thin and if I zap with the 70amp car battery I might blow through them.It will be interesting to see what voltage is present in the different batteries so must get one soon.There seems to be so many I'm not sure what I should get so any ideas would be welcome.

[PaulUK]

Well I got a multimeter today and tested the batteries that I have zapped.The clear winner so far is the vacuum battery which is 3.2 volts and now reads 4.1 volts after charging,the 700 mAh ones which are 1.2 volts are reading 1.35, the drill battery only reads 1.23 volts so well shot, I guess there are 8 cells in the pack so will try soon to do them from the car battery before I think about taking the pack apart.
I did wonder if the technique works with Nmh when they die?.

[mael]

Sounds good Paul.

In my experience, and from reading other people's stories about dodgy NiCads and their newer cousins - but esp NiCads, it is best to keep them fully charged (if you get that far).

I have mentioned before, and also experimented with them and found that the batts can last years longer if they are kept adequately charged.

NiCads seem to like a charge up to 1.45 V per cell, but 1.4 is fine. I wouldn't keep a NiCad much above 1.4 V, and heat is certainly sure to reduce the life of an already weary cell.

* I reckon you should get a 50,000 mFd cap, charge that, and use that to zap the cells. - But a car battery is more fun.

[SeaMonkey]

I'll second what Mael has said!

Some of the NiCds that I've dealt with are very stubborn. Apparently the dendrites are very numerous and massive in some cases. But with perseverance and sufficiently high current pulses even those eventually come around. Some of my NiCds are approaching 30 years of age and still working well. As long as you're able to zap them without their getting hot or blowing their seals you'll be really surprised how long they'll go!

I've only had to zap one NiMH cell. Somehow a short had developed within it and it only took one zap to clear it. Since then (3 yrs. ago) it has functioned as new and still goes strong.

[PaulUK]

[mael]

[PaulUK]

[SeaMonkey]

Paul,

The 'warmth' of your battery pack after charging is normal. Many chargers use the increase in temperature of the NiCd to signal 'full charge' and at some pre-programmed temperature as sensed inside the pack will shut down charge current.

It is, unfortunately, those types of chargers which tend to damage battery packs as they gradually develop shorted cells.

If you haven't yet you'll enjoy what the site has to offer.

[mael]

[mael]

[mael]

[PaulUK]

[mael]