When the Bluetooth icon in your Menu Bar looks low on juice, your Mac is – of course – warning you that something paired to it has a low battery. (Your icon may look different, depending on what kind of Mac/version of OS X you have). Although there’s no need to get into a panic about it (it can be weeks before they actually run out, depending on your usage), you might want to check out what’s exactly running low. Your Mac will eventually warn you by flashing an image and message onto your screen, but your Bluetooth shortcut will give you access to this information any time you want.
Just click the Bluetooth/battery icon in your Menu Bar. As you can see in the screenshot here, two things have low batteries. If you absolutely have to know exactly how much juice you’ve got left, just mouse down to your device (those that are connected are in bold) and a dialogue box will pop up and give you the percentage of battery life remaining.
If you didn’t have a Bluetooth shortcut and you wanted to check your battery levels, you’d have to go to , System Preferences, and then individually click your Mouse, Keyboard and Trackpad icons to find out. So it’s a handy little time-saver.
What’s that you say? You don’t have a Bluetooth shortcut on your Menu Bar and you don’t know how to put one there?
Here’s a link to my original post that tells you how to do it. You’re very welcome. 😉