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My Mac 'dies' if it has less the battery level is below 3%. Is it possible to force it to hibernate when the charge is at 5%?

I have a Mid-2009 MacBook Pro with 683 load cycles and the latest SMC available (1.47f2)

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up vote 1 down vote accepted

The SMC and device firmware control power management and I've not seen any parameters you can simply adjust to change the thresholds but clearly, Apple could program that and push an update if you had infinite money or influence.

That being said, it's quite easy to run a background command to log the battery levels to a file and parse that file. Whether you prefer python or perl or simpler shell commands would influence the solution you implement.

So yes, it is possible to program such a tool, but you'd need some basic scripting knowledge to implement a higher limit to enter hibernation.

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Inspired by @bmike excellent suggestion, I found this (alecjacobson.com/weblog/?p=1366) Hope this helps. –  Global nomad Feb 17 '13 at 15:20
    
Besides this script, is there any way to re-calibrate the battery so that my Mac understands when it is going below a critical level? –  mariosangiorgio Feb 18 '13 at 14:30
    
No - the batteries that were removable with a metal case used to go along with firmware that would calibrate during a full charge, settle, discharge, sleep and sit for 5 hours procedure. The new unibody Macs with internal batteries self calibrate and are much more complex. There is a voltage discontinuity and it could work itself out, but is likely to further degrade over time. The firmware does try to avoid this event, but unless Apple releases a firmware update (like they just did to improve handling of batteries with more than 1000 cycles) - your bet is to adapt or replace the battery. –  bmike Feb 18 '13 at 14:47
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