Do you have the Bluetooth icon showing in the menu bar? If so that displays the battery level of any Apple BT device. Just click on the icon and on the device name.
If the Bluetooth icon is not showing in the Menu Bar, open System Preferences and click on Bluetooth and at the bottom click that option.
If you downloaded the Dashboard widget that Kevriano linekd to above, you have to launch Dashboard to view it. Push F4 on the keyboard to open Dashboard.
Thanks to themitch, that's exactly what I was looking for. This battery-level business has been a rock in my shoe for a couple of years. The Mac OS low-battery popup is too ephemeral; the blinking indicator in the BT icon is too small and easy to ignore; seeing the levels in the BT menu requires thinking about it and making mouse gestures; widgets like iStat Pro and Mighty Monitor require thinking about it and bringing up the Dashboard. BtBatStat does just what I want -- putting something small but noticeable on the screen all the time, so I can tell the battery status at a glance. A donation and suggestions will shortly be on the way to the author of BtBatStat!
Now the remaining problem is that the percent numbers produced by all these little monitor apps are all different! I'm going to have to calibrate BtBatStat wrt the Mac OS measure. But maybe that's a topic for a different thread.
It should have downloaded to the Downloads folder. Double click on it and you may well receive a message about being locked. Go into System Preferences > Security and Privacy > General and click on the padlock at the bottom of the pane. It will ask for your admin password, and when supplied, change Anywhere. Double click and it will open and run.
Go back in and click the padlock and choose Mac App Store and identified developers. That is Gateway which helps keep malware out of your Mac.
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