Zap New Life Into Ni-Cads


Apparently you can revive dead Ni-Cad batteries by zapping them with high voltage. Some people have used welders in the past, but many of us just don’t have access to one. This project shows you how to hack a disposable camera into a battery revival device. This could be very cost effective. A single regular AA battery could revive many Ni-Cads. Remember, this doesn’t charge them, just makes them able to be charged again.

18 thoughts on “Zap New Life Into Ni-Cads

  1. it can work i’ve revived many batteries by using similar methods. however there is a big catch to this. you can (and i have) blown up batteries by using the zap method. it can be extremely dangerous and you should wear full face gear. exploding batteries are not a fun thing so just make sure you take precautions because you can always go buy some more batteries but you only got one set of eyes.

  2. For these purposes I always use 12V 7Ah SLA battery. I never had a single cell explode, though you are just supposed to connect it for a fraction of a second, not till it is charged :) And observe polarity …

  3. well yeah that might be part of my problem, normally i’m good enough that i don’t blow them up, but then again i go a little overboard. normally i just use a dead mans cord and hit it quick. gets the job done and i don’t have to go looking for all sorts of things.

  4. Take note: *** THIS IS VERY HAZARDOUS ***

    Zapping or charging anything with a higher than rated voltage is not recommended. And of course, instructables does not actually tell you to take any precautions (e.g. facemask, gloves, etc).

  5. This does work, but can give mixed results.
    The info in the instructable is a bit off, sometimes the reason a cell is “dead” is due to a tendril of fine metal that forms over time and shorts the cell. Putting a quick, hefty voltage through blows the tendril up (like blowing a fuse), allow the cell the charge normally. But, sometimes the tendril has punctured the insulation in the cell, allowing the cell to discharge more quickly, so a revived pack may hold a decent charge if used quickly, but die much more quickly on the shelf.


  6. Actually, what’s being done here, AIUI, is the burning out of the dendrites that form in NiCd batteries (and *only* NiCd batts!).

    Instead of a high-volt source I was taught to use a high-AMP source, like a car battery or other 12V source – anything larger than a housebrick should be big enough. One would then just momentarily (as in brushing a wire to complete the circuit for, like, a ms) complete the circuit where you’d have the + of the BigBatt connected to the + if the NiCd, and the – of the BigBatt connected to the – of the NiCd.

    This high-amp short circuit tends to burn out the dendrites that prevent the NiCd from accepting a charge.

    Beware hydrogen gas from Lead Acid (BigBatt) type batteries, esp during/after charging them.

    When you brush the wire to complete the circuit you’ll get a spark. This is part of the fun.

    If the NiCd begins to feel warm then stop immediately.

    I sometimes brush a few times, for good measure.

    This ‘revival’ process works very well to revive a dead NiCd that won’t accept a charge from its charger. After reviving charge as per normal.

    Wear eye protection.

  7. This method is for fixing batteries where an internal piece of metal “dust” shorts between the anode and the cathode. A small high current “zap” should be enough to burn out that particle meaning you can now go ahead and charge the battery.

    You shouldn’t do it for more than about 2 secs, certainly not enough for the whole battery to get noticably hot, since then yes, like h20 said it could explode.

  8. this method ( high voltage pulsed zapping ) is usually used to revive lead-acid car batteries that have lost capacity and power but still have good voltage. have no idea if it will work on nicd batteries, but if you want to try to revive car battery do it outside, and please use the eye protection gear. batteries are sealed containers and they can explode if overheated or overloaded.

  9. I’ve heard of zapping NiCd’s with HV before, but never with high-current sources (eg: car batteries)
    Can you use a 12V car battery to zap a 12V drill battery back to life, or does it have to be a larger voltage? (like in the case of normal charging)

  10. So I decided to try this out. I checked my target battery for polarity, but found it had 0V. I plugged it into my charger, and it ended up shorting out the charger, blowing up a resistor and melting parts of the case and pcb.

    Is this battery in too bad condition to be recovered?

  11. most drill battery packs are made up of sub c’s of some sort. they could be nicd, nimh, or lithium. I know nicd’s can be revived sometimes, it really is hit and miss. DO NOT try that with lithium ion battery’s you will regret it and end up hurt. i have never really tried it with nimh so i can not answer there. however there is a larger issue with zapping drill battery packs, they are normally packs that are normally spot welded so rebuilding them if you tear them down can be a pain. also getting them hot is not the best idea in the world either but that is a discussion for another day.

  12. As long as the cells in the pack are NiCd you should be able to try this with a drill pack if you open the case and zap each cell individually. Doing the whole pack wouldn’t be a good idea since some packs might take more of a hit than others depending on their state. You wouldn’t need to break the welds on the cells, just contact each cell for zapping individually and reassemble the pack.

  13. If you do this, be ready to PULL the connection apart instantly as it can weld itself! For a pack with a lot of cells, reverse the polarity or, if it has some decent voltage in it, just short it. I’ve never seen an explosion but I suppose it’s possible. Then again, I never let it go on as much as one second.

    The batteries will NOT be like new, but they may work for quite a while. I do this for my cordless phone packs, as they go bad often. In that case, I have to be careful to do one cell at a time so as not to blow the built in fuse that’s in the pack.

    The use of a disposable camera is a neat trick, though.

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