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A new way to resuscitate a dead battery
Authored by: johnsawyercjs on Sep 26, '03 03:54:49AM

Here's a tip from Macfixit, and my response at the time:

Macfixit, Feb 27 2003:
Shorting an iBook's battery to reset it [my advice: use a fast-blow fuse instead]
Warning: Before we continue with this information, it's very important to note that you should not even consider attempting this procedure without the aid of a skilled electrician, and you should be aware that your iBook battery may be destroyed. Again, do not attempt this procedure on your own. Take your iBook battery to an authorized electrician or another specialist.

A Mac service provider who wishes to remain anonymous describes the process of shorting a defective iBook battery (which was temporarily ruined by static electricity), in order to restore its function.

"One of my clients was using an 800 MHz Combo 12.1" iBook purchased late 2002. As he was using the computer, he got a mild shock of static electricity from someone. It froze his computer (OS X), completely requiring a reboot. Upon reboot (plugged in to wall), the computer stated that no battery was present. After removing and reinstalling the battery, the computer stated the battery was at 0%, even though it was actually fully charged. The battery itself showed one steady light. Nothing he tried would change anything. It also would not charge, though the orange charge light would come on.

"We decided that the battery itself needed to be reset, since he knew it was fully charged (and only a couple of months old). Of course, with only one button to press, we couldn't reset it. By fluke, shorting out the two outermost power leads on the battery together, for a split second (still makes quite a spark) actually reset the battery. The four lights cycled from 1 to all on a couple times, and then all 4 lights came on.

"He inserted two small pins (the kind that you get with a new dress shirt) into the outermost contacts. Then, using a multi meter, he measured the voltage, and then briefly zapped the two together in a single 'motion.'

You should also include a fuse in the (short) circuit. Without a fuse there is a potential for the shirt-pins or other leads to electrically weld together and draw a huge current for an extended period. They'd also get very hot, making it difficult to remove before damage was done.

If you are one of the several readers having an iBook battery problem, you should first attempt invoking your Apple warranty or AppleCare (if you purchased the coverage) before attempting home repairs such as the one described above.

UPDATE: James Sentman offers some further explanation on why shorting the battery works, and further caution about the procedure:

"I might be able to shed a little light on why shorting out the battery would cause it to reset. Every lithium ion battery pack has a set of sensors and circuits to protect the batteries from things like charging at high temperatures, complete discharge, and short circuits. If this chip sees excessive power drain like from a short, it will temporarily disconnect the cells to protect them from catching fire or exploding. So by shorting it out you are basically power cycling the other circuit in the pack that keeps track of the power level in the battery. However, even with this protection built in it is important not to short the battery for more than the moment necessary to do this. While I have no reason to think that these circuits are prone to failure, if you're lucky enough to get one that is not functioning, shorting the battery will cause the cells to catch fire and even explode very quickly without this protection."

Posts in response:
Authored by: jonsaw on Thursday, February 27 2003 @ 01:37 PM PST
I'd recommend using a fast-blow fuse in-line with the wires you're
using to short the battery contacts, instead of simply using wires
or pins alone. A half-amp fuse should do the trick. If you find that
a fast-blow fuse opens too quickly, try a regular fuse. Since it's
still possible the battery could explode, you might also want to put
the battery into a box, with holes for your hands, and wear thick
gloves.



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