That's why it gives the warning, you don't want to go below 10%
you can go to the Apple logo in the menu bar hold the option key and click it, then click system information, in the left column>power, check that the battery condition is normal.
Don't run it down so low.
I don't see any great impronement, but here is the pram reset:
I never go below 30%, every 50% is a half cycle.
Thanks for your feedback sanjampet,
My battery is brand new - and the status is ok.
To be honest - this can't be it. The sudden shut down/power fail is for sure not the reason for the the 10% warning. I've worked with many Macbooks - none of them did behave like that. I always could drain the battery down to 0% if necessary and then the Macbook just went to sleep.
SMC reset didn't help, now I'll try the PRAM reset.
>>How can I calibrate the battery correctly if a complete shut down happens before reaching 0% ?
Follow http://support.apple.com/kb/HT1490 which you've probably seen, taking care to wait 5 hours after it switches off.
If the problem persists after that & the SMC reset - it may be the battery... a cell inside could be dropping voltage very rapidly once below a certain level, and this prompts the shutdown.
If you use this command in Terminal :
ioreg -l -d 10 | grep CellVoltage
it will show the indivdual cell voltages, which as the battery discharges, you may see a wide variation in.
I recently had the same problem on the same model.
Thanks Andy for the feedback.
I've started logging/tracking the battery voltage with a perl script to see whether the voltage suddenly drops. Actually it does, but I'm not sure whether the drop is correct or not. My guess for the behaviour: Battery capacity indicated is wrong (too high) and when the voltage drops, to the Macbook thinks it should still have some juice left. There should be a way to set the capacity (instead the 5044mAh I'm reading to let's say 4700mAh) without the need of going through the hard shut downs. Whenever I have a hard shut down, the capacity reading decreases for some mAh......
Any idea how to overcome this problem?
Thanks for any advice
What figures do you have that suggest a problem ?.
This persists after following the calibrate procedure ? - if so, I don't know any way to convince the system to shut down earlier.
If it's an Apple battery, I'd return it in warranty : if not, it may be one of those things (I recently swapped to a 3rd party one that does much the same, although I haven't got around to calibrating it properly yet... but new genuine ones don't need it, in my experience.
Every time I use the MBP, it shuts down at some 6..9%. Calibrating doesn't seem to work correct...
I modified the terminal command to show also the remaining charge. Additionally I wrote a perl script to record battery voltage / charge.
I'll post this once it's done.
..And yes - it is a 3rd party battery that causes this. Should have bought a genuine battery....
Well although the battery might be new to you doesn't mean the battery was produced, made, within the last year or so.
All batteries have a self life. Whether they are used or not they only last so long. Once any battery starts to age it won't hold as much charge as it would of when freshly made. I suspect the battery you now have was made serveral years ago (Sorry but most people replace their computers within 3 to 5 years). So it has been sitting on a shelf for those years and losing the ability to hold as much charge as it would of when made. Not sure how to check the Build Date of the battery.
Shown below is the discharge curve of my A1275 battery (it contains 3 individual cells) vs. time. After 2h6min the hard shutdown occurs each time - at a 'remaining' capacity of ~300mAh.
The battery itself doesn't get calibrated to a lower value, it remains at some 5044-5090mAh when doing a calibration.
The true capacity seems to be only ~4600-4700mAh, but since the calibration procedure doesn't work successfully with this battery, the problem will persist.
Maybe there is a way to lower the battery capacity on purpose to a lower value. There might be a possibility with IO_reg.... (?)