Zapping Laptop batteries

From: Joe <rigdonj_at_cfl.rr.com>
Date: Fri Nov 15 08:24:00 2002

At 09:05 AM 11/15/02 -0600, Gary wrote:
>Lawrence Walker wrote:
>>
>> This has come up before but I can't remember it being resolved.
>> I often see suggestions for rejuvenating failed or dying laptop batteries using
>> a hi-amp source to flash them and break down the built-up crystals.
>
>What really happens is that minute 'hairs' grow from terminal to
>terminal in the cell, effectively shorting it out. To remove them
>requires a flash of current to 'burn' them out. Either a high current
>source (10A or more) or a large capacitor discharged into the cell does
>the job.

   I have used an automobile battery to "zap" them. Shorting a NiCad to an auto battery for just a split second usually burns out the whiskers. HOEVER the fix usually doesn't last long. One of things that happens when the whiskers grow and short the electrodes is that they also pucture the membrane that separates the electrodes. Once that happens, the battery doesn't last long. ALSO zapping NiCads can can over-pressure and rupture the vent and possible spray out electrolyte (potassium hydroxide solution) if get them too hot. Not only is this an immediate hazard but it can also cause slow leaks that go unnoticed until the electrolyte eats up the circuits in the device that the batteries are installed in.

   I'm not saying not to zap your batteries. Zapping them is a great way to get them working again FOR A SHORT TERM. That will at least let you test the device to see if it works before investing money in new batteries. However just be aware of the dangers of zapping and DON'T leave the batteries in the device after you're done testing it.

    Joe
Received on Fri Nov 15 2002 - 08:24:00 GMT