After upgrading to Lion my Magic Mouse's level indicator seems to be broken.

For the whole week it was reporting solid 100% on a pair of used batteries that were about 65% before upgrading. I swapped the batteries naively hoping it'll change anything and it actually did. It's now solid 95%!

Screens from both system preferences and Bluetooth icon in the menu bar:

mouse battery level in prefs mouse battery level in Bluetooth

What's interesting, iStat Pro dashboard widget seems to be reporting a correct level:

mouse battery level in iStat Pro

Has anyone noticed such a problem? Or maybe even found a solution to it?


You are not the only one. Mine says the same - 100%. This is a bug. The terminal command for querying the battery percentage (probably what iStat Pro uses) reports: "BatteryPercent" = 82

For bluetooth mouse:

ioreg -n "BNBMouseDevice" | grep -i "batterypercent"

For Apple bluetooth keyboard:

ioreg -n "AppleBluetoothHIDKeyboard" | grep -i "batterypercent"

I've posted this in the Apple Bug reporter. Hopefully it will be fixed in an future Lion update.

Here is another thread discussing the same issue. https://discussions.apple.com/thread/3211868

  • That explains it then. Let's hope for a prompt hotfix to Lion.
    – Michal M
    Jul 27 '11 at 12:53
  • I can confirm this too. The Bluetooth Menu and System Preferences report 66%, but it's actually 46%.
    – René
    Jul 27 '11 at 13:44
  • Here on Lion 10.7.2 the bluetooth menulet reports 7% and ioreg 20% — so I guess it got fixed too much. :-D Nov 3 '11 at 13:15
  • 1
    Yep. Still there in 10.7.2. I haven't had any response back from Apple about the ticket either. I'm interested in where this other number is coming from. Where are they getting it?
    – Nate Bird
    Nov 14 '11 at 13:48
  • In 2018, 10.12.6 reports keyboard battery percentages differently from menu bar/system preferences to ioreg. In my case, currently ioreg reports 77% while system prefs and the menu bar report 100%.
    – Andrew
    Apr 8 '18 at 6:07

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