[Cialug] bios fubar?

Nathan Stien nathanism at gmail.com
Mon Jan 14 10:57:57 CST 2008


On Jan 14, 2008 10:48 AM, Daniel A. Ramaley <daniel.ramaley at drake.edu> wrote:
> I ask because i have a white MacBook and would prefer to avoid the same
> problem. About once every 3 or 4 months i drain the battery to the
> point that the machine spontaneously shuts off. So far that hasn't
> caused any problems; actually i do it intentionally since after a few
> months of use the battery gauge isn't very accurate but it corrects
> itself after a full discharge/charge cycle.

I advise you not to deep-discharge lithium-ion batteries.  It is not
good for them -- it's bad even to leave a mostly-discharged one
sitting on a shelf.  Deep-discharge helps with other battery
technologies like Ni-Cd and NiMH, but Li-Ion batteries have safety
issues when deeply discharged, and generally contain circuitry to
prevent them from going too low.

Battery meters are pretty much always just guessing, and their ability
to guess the state of the battery declines as the battery itself wears
out and deviates from the engineers' models.  By deep-discharging your
battery you might get a little more short-term accuracy out of your
meter, but at the cost of the long-term health of your battery.

I am just a general-purpose electrical engineer, not a battery
specialist, so I welcome correction from anyone on the list who knows
better.

- Nathan


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