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MacBook turns off at 30-40% battery

P

PhazonUK

macrumors 6502
Original poster
Jun 1, 2010
321
0
This has happened twice not. I'll be using my MacBook and it will have around 40-60 minutes worth of battery left, around 30% or 40%, and it will just shut off. No warning at all, it just turns off as if I've pulled the battery out.

I plug it into the mains and turn it back on and it says I have at least 30% battery left.

Is my battery dying?
 
Unfortunately I don't have an answer for you but I am also having the same issue. It occurs whether I have the power cable plugged in or not.

Only started happening in the last 24hrs and no pop up comes on when running on battery to say it's low on power.
 
mallyman said:
Unfortunately I don't have an answer for you but I am also having the same issue. It occurs whether I have the power cable plugged in or not.

Only started happening in the last 24hrs and no pop up comes on when running on battery to say it's low on power.
Click to expand...

Have you tried calibrating the battery?

What are you charge cycles and battery information?

Cheers!
Chris
 
Hi, not calibrated the battery as I'm not sure how it's done. The battery info is as follows:

Health Information:
Cycle count: 562
Condition: Normal
Battery Installed: Yes
Amperage (mA): 3205
Voltage (mV): 11881
 
I have looked at the instructions for calibrating the battery and this won't be possible. The battery disconnects at the 30-40% remaining level. To confirm I push the button on the battery and I am presented with 2 lights so not low enough to run through as the instructions advise because I don't get the 'low battery' alert anymore.
 
Same problem plus fluctuating health/max charge values

I have the same problem. Battery dies without "reserve power" warning. When I start up again, iStat and Coconut battery both show 20% charge and 77% health. I have tried recalibrating twice. I have also noticed that the health of the battery fluctuates. Sometimes it is 77% sometimes 71% then back up to 75%, etc. Readings for maximum charge vary accordingly. Is the battery fried?
 
Julay said:
I have the same problem. Battery dies without "reserve power" warning. When I start up again, iStat and Coconut battery both show 20% charge and 77% health. I have tried recalibrating twice. I have also noticed that the health of the battery fluctuates. Sometimes it is 77% sometimes 71% then back up to 75%, etc. Readings for maximum charge vary accordingly. Is the battery fried?
Click to expand...
It's normal for the battery health to fluctuate. If you've properly calibrated and your Mac shuts off without warning when the battery isn't showing to be depleted, try resetting the SMC. This should answer most, if not all, of your battery questions:
 
You can also try an when powering up the macbook, hold the alt key and let it drain the battery (don't let it boot mac os x or windows). It ignores power management and only cuts off when the battery is really empty.
 
Of course. The point is to not load the OS. So that only when the hardware cuts off the power it powers down. Just let it sit for a while, it heats the macbook a little while showing boot able partitions / volumes.
 
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