G4 Powerbooks] Resetting battery gauges...

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DoctorClu's picture
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Joined: May 3 2005
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On my G4 Powerbooks both computers have their battery gauges off so that the computers shut down wayyy before the battery levels indicate that the batteries are out or even low.

One, with a newish battery, knocks out at 50%, another with a older but good battery knocks out at around 30%.

Apparently I need to reset the gauges of the battery levels somewhere, how do I do that?

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Dr. Webster's picture
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Joined: Dec 19 2003
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I'd start by zapping the PRAM

I'd start by zapping the PRAM and performing a PMU reset:

http://support.apple.com/kb/HT1431

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dankephoto's picture
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maybe try resetting nvram

try the nvram reset thing* (with the battery in place of course,) I recall that having an effect with some new world 'Books' batteries.

As Doc W mentions, the PMU reset is the first thing to try.

These batteries controllers are accessible from the Mac over a serial interface, but I've never found any sort of generic utility to rewrite a battery's memory. The Battery Reset Util for Lombard/iBook/etc. does just that for their batts, but sadly I've never found any other similar util that will work with any other machines.

Also, consider that the batteries may simply be faulty (usually a sub-par cell or two.)

dan k

* drop into openfirmware**, "reset nvram" rtn, "reset all" rtn

** hold O, F, cmd, option keys on startup

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DoctorClu's picture
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Thanks!

Thanks for the input!

DoctorClu's picture
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reset, unknown word

Trying the "reset nvram" I get "reset, unknown word"

That is with a 10.3.9 model and a 10.4... model

(Ok, found out you need to have a hyphen in there...
"reset-nvram"
"reset-all"

cwsmith's picture
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Joined: Oct 13 2005
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you might also try this

reset-nvram
set-defaults
reset-all

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DoctorClu's picture
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Thanks once again!

Thanks once again!