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n175h 06-16-2012 03:48 PM

Tap surging Nicad batteries
This is somewhat electrical, though not house wiring. Has anyone tried this?:

I just tried it on 4 Sears 19.2v craftsman batteries using 3 twelve volt batteries in series to get 36 volts. It didn't seem to do any sparking or anything when I did as directed. I put them all in the charging station to see what happens. I should know something tomorrow. I'm not getting very long service out of the these batteries for my tools. I saw a guy do it with a mig welder on Youtube, but I opted to use the batteries instead. I don't know if it will resurrect them or not.


ddawg16 06-16-2012 05:02 PM

It works in some cases....but in most, it's a waste of time.

NiCads have a finite life...typically 300 to 1000 cycles depending on use and environment (they don't like it too cold or too hot).

The worst thing you can do to a nicad is to leave it on the charger too long or to not use it at all. When a nicad sits idle, it has a tendancy to develop an oxide on the plates. In case you have never looked inside one, a typical battery is basically a perferated metal strip coated with nickle...wound up along with an insulator and stuffed inside a can. They then fill it with the cadnium electrolyte....

So when you don't use the battery...the oxide starts to coat the surface of the nickel plate. The effectively reduces the total surface area of the battery....which is a direct function of the ah (amp hour). This is what some people like to call the 'memory'....

In other cases, you might get a breakdown in the insulation between the plates....this effectively shorts out some plates reducing the ah.

Basically...the above trick might burn off some of the oxide....but for the most part....the battery is done.....

mpoulton 06-16-2012 05:36 PM

I did it on NiCd packs for RC cars back in the day. Used two car batteries for 24V on 7.2V packs. It seemed to rejevenate them a bit sometimes, but was usually not worth the hassle. By the time a battery needs that treatment it is on its last legs and you won't get much more use out of it.

n175h 06-16-2012 10:54 PM

I kind of figured it may be a snake oil solution:huh:. Several of the guys I work with have the lithium tools (mainly Makita). They seem to be happy with them. I always wondered if the 3x price was worth it for the upgrade, however.


ionized 06-18-2012 07:38 PM

I used to do this with individual NiCd (1.2V) cells0 using a largish capacitor. It worked quite well. It seems safer than using a lead-acid battery with a huge capacity compared to the NiCd.

zappa 06-19-2012 05:18 AM

As others have said the battery is normally ready for replacement when this happens but it does work and can get you a little extra life. I used to do this with mixed results on 2-way radio battery packs where one or more cells in the series cluster would go dead and render the whole battery useless.

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