Bluetooth connection instability with Magic Mouse on El Capitan I'm using a ~3 year old Apple Magic Mouse (1st generation, removable AA batteries, part number: MB829LL/A), and it has started to give me brief disconnection warnings, but always automatically reconnects in .5 to 3 seconds or so. Here's a syslog snippet on gist.github.com. Clues so far:


Started after upgrading to Yosemite / El Capitan (I only ran Yosemite for a week or so before upgrading to El Capitan)
Only happens in cafes or on campus, i.e., where there are other devices around.
Usually only ever disconnects as soon as I use the mouse after not using it for a few minutes. I.e., usually the mouse sits for several minutes and doesn't have any issues when I start to use it again; sometimes it has this disconnect aneurysm while actively using it.


Things I've tried so far:


Removing the mouse, restarting, and pairing with it again via the Bluetooth PreferencePane.
Ensuring the batteries are fresh / completely charged.


Based on #3 and what I gather from the logs, I'm guessing it's going into some sort of sleep / standby mode, and not always waking properly. Perhaps there's some OS X system setting that will let me turn this off or increase the period of time that counts as sleep-worthy inactivity?
In System Preferences for Bluetooth you can check the box to "Show Bluetooth in menu bar." Then, hold down the option key and click the Bluetooth icon when paired with your device. You'll see a new option to "Create Diagnostics Report on the Desktop." This will give you more details to further debug or diagnose what's going on, particularly the files pmset_everything.txt, and com.apple.Bluetooth.plist in the section on BluetoothStats. My system displays 0 for all the stats except 1 for CommandTimeouts.