macbook pro stops with battery at 70%

[pier]

Then I can reboot work for half an hour until battery is like 50% then it shuts off again... then I can reboot again and work for some more time.

I've checked with coconut battery and when the computer stops at 70% I still have like 1700 mAh...

I've reset PRAM, power management, etc...

Of course my battery is old, but it should work until 00%... not stop at 70%.

Before I spend like 100$ (that is what a macbook pro battery costs here in Mexico) I'm willing to try anything...

Any ideas are welcome

 

[GregGebhardt]

Is there a calibration feature to recalibrate the battery? I know my Thinkpad battery had a similar problem and after using the calibration utility, it worked well again.

 

[pier]

There's this apple article about how to do it...

http://support.apple.com/kb/HT1490

I will try but honestly, nothing in my macbook works as described in that article. I don't get any message before my computer is shutting down, my computer does not go to sleep, it shuts off...

 

[Pax]

Almost certainly a bad battery. Sometimes they show this behaviour. The battery simply can't deliver the power it promises the Mac, so the Mac shuts down early.

 

[pier]

Almost certainly a bad battery. Sometimes they show this behaviour. The battery simply can't deliver the power it promises the Mac, so the Mac shuts down early.

But then why does it work again if I restart the computer?

 

[ValkyrieLenneth]

Your battery is suffering the same problem as mine. I think it is because one or more cell is dead. Buying a new battery is the best solution.

 

[pier]

Your battery is suffering the same problem as mine. I think it is because one or more cell is dead. Buying a new battery is the best solution.

This is what I feared... but then I've read in apple's forums that some people still have the same problem even changing the battery....

 

[Pax]

But then why does it work again if I restart the computer?

My guess: the battery needs to deliver a certain minimum voltage, say 11 volts, to run the Mac. When the Mac asks for more power from the battery (eg the CPU load increases) the voltage drops a bit. So your Mac is fine until the CPU load reaches a certain level. Then it dies. You can reboot and run again as long as the CPU load stays light. Repeat.

A new battery would deliver 12 volts not (eg) 11, so the problem would not occur.

 

[ValkyrieLenneth]

This is what I feared... but then I've read in apple's forums that some people still have the same problem even changing the battery....

I bought a new battery from Apple Store and the problem was solved

 

[pier]

My guess: the battery needs to deliver a certain minimum voltage, say 11 volts, to run the Mac. When the Mac asks for more power from the battery (eg the CPU load increases) the voltage drops a bit. So your Mac is fine until the CPU load reaches a certain level. Then it dies. You can reboot and run again as long as the CPU load stays light. Repeat.

A new battery would deliver 12 volts not (eg) 11, so the problem would not occur.

Thanks for the explanation, it makes a lot of sense.

I guess I'l have to buy another battery...