Mouse keeps disconnecting

Might be corrupted Bluetooth preferences ...

Open a Finder window. From the Finder menu bar click Go > Go to Folder

Type or copy paste the following:

/Library/Preferences/com.apple.Bluetooth.plist

Click Go then move the com.apple.Bluetooth.plist file to the Trash.

Restart your Mac then re pair your mouse and keyboard.

Set up your Apple wireless devices - Apple Support

If Carolyn's fix doesn't help this fix by beingajen might:

beingajenSep 5, 2016 8:16 AM in response to Airbus 320

Level 1 (4 points)

Sep 5, 2016 8:16 AM Re: why does the apple mouse continually disconnect and then reconnect. regardless of battery state - new or otherwise.in response to Airbus 320

I had this issue and then found a feed from 2012 which discussed a solution. My mouse goes back to 2014, but this it stop the disconnecting, so worth a try.

Not all AA batteries are precisely the same size and the channel in the Apple products and the batteries themselves are on the wider side. As such average batteries move around in the mouse when moved, and every time they lose contact with battery plates than the bluetooth disconnected. Option 1 is to go to an Apple shop and buy apple branded rechargeable batteries. Option 2 is the one I opted for. Fold up a piece of paper about the size of a post-it note into a shape that fits between the 2 batteries. Then fold another one to the size that fits above the batteries to the width of 3-4mm wide. Close the mouse unit up. This reduces the movement of the batteries and should address the issue.

I hope this works.

I did a similar fix but I folded up small pieces of Al foil and put them between the positive poles of the batteries and the contacts. That fixed it for me.

I have that issue only when I volunteer at a local museum and take my Mac and Magic Mouse. I've decided it is interference with the base station for the wireless phone that is on the desk. Doesn't happen at home.