Ask Different is a question and answer site for power users of Apple hardware and software. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

With the iStat Nano dashboard widget I can see the health of the battery on my 10.6.8 Macbook Pro. This health value jumps from 76%, to 84%, to 80%, etc. just in a few hours. I've reset the SMC already, this did not solve the problem. I've calibrated the battery yesterday, this did not solve anything as well.

What could be causing this behaviour?

share|improve this question
What's the reported battery health? You can check that in System Information. – Gerry Oct 12 '12 at 8:10
The system info says now: Full charge capacity (mAh): 5211, Condition: Normal. iStat Nano says the health is now 80% – Saaru Lindestøkke Oct 12 '12 at 8:23
Can we also exclude it's a problem with iStat Nano? Can you enable displaying the battery pct. in the menu bar and observe if that's any different? – Gerry Oct 12 '12 at 8:24
I think I'm not entirely clear on what battery health is. It is the Full charge capacity divided by the Designed capacity. In my case the Full charge capacity is 5211 mAh and the Designed capacity is 6500. This yields an 80% battery health. This battery health should not change every hour. What I am wondering is that why my Full charge capacity changes randomly. The battery pct. in the menu bar only shows the amount of charge left w.r.t. the Full charge capacity. – Saaru Lindestøkke Oct 12 '12 at 8:32

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.