Battery Calibration keeps failing

[mark28]

The calibration of January failed when I used the recommended 5 hours. Last night it failed again when I used 7 hours.

So now my question is, how long should I keep the MBP sleeping then?

 

[Fubar1977]

How do you mean by "failed"?
There is no notification as to whether calibration has been successful, as long as you follow the guidelines you should be fine.

http://support.apple.com/kb/ht1490