NTLK Rebuilding your own 110/120/130 battery pack

From: Mike O'Brien (obrien@leonardo.net)
Date: Sun Jan 09 2000 - 01:15:01 EST

        No one seems to have answered the gentleman's question from a couple
of days ago. He pulled the metal frame off his 130's expired battery pack and
loaded in all new NiCd cells. He wondered if his cells were the same as
Apple's: same voltage, etc.

        The answer is yes. The voltage of a NiCd cell is determined by the
redox chemistry of the elements nickel and cadmium. Any cell made out
of these two elements is going to have the same voltage, 1.2-something volts,
at least when it's freshly charged. As it discharges, the measured voltage may
fall due to deposits on the electrodes preventing free movement of the ions.
This is an illusion; pay no attention to the oxides behind the curtain. The
cell chemistry gives 1.2 volts and any AA NiCd battery will work as well in a
130 battery pack as any other.

        In fact, usually better. I think the original cells used by Apple
had a capacity of something like 600 milliamp-hours. Cells are a lot better
today. I used the four-AAs-and-a-piece-of-cardboard trick to build a fake
rechargable pack for my 130, using cells with a capacity of 1100 mAh, and
boy oh boy does that thing last forever.

Mike O'Brien

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