Magic keyboard loses connection unless plugged in to recharging cable

Before you run off to the Apple Genius Bar....

The first thing to suspect is interference from other devices. See what other tech is broadcasting near the computer--wireless phone base stations are well-known for interfering with Bluetooth signals.

Apple reference: Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support

At a museum where I volunteer, the volunteer desk is also "ground zero" for the center's tech. Within ten feet on the desk are a computer with bluetooth enabled, a wireless-capable printer, a wireless phone base station, the mode/router, and a credit card machine. My Magic Mouse looses connection there quite often; at home, almost never.

Nope....I don't think it's a common problem. what you could do (*here I'm assuming that the Magic Keyboard is Bluetooth*) is to go to the Bluetooth menu, at the top right part of your screen, next to the Time machine icon on the left and the wifi icon on the right (looks like an upside down triangle or wedge of cheese), then go to Bluetooth Preferences by clicking on the cog at the bottom of that menu. You may wish to forget that keyboard for now. also make sure that your iMac's bluetooth is turned on and that it is discoverable. Honestly--who just loses an iMac??? (that was a joke). Then do a reset smc/pmu and zap pram for your iMac. How to do that can be found on Apple's support page for desktop computers, or if you're impatient like me, google or yahoo can get that for you pdq. before doing the reset smc/pmu, turn the keyboard off by sliding the power switch until the green light goes off. disconnect power cable for about 30 seconds or so. plug in power cable. There isn't any other way to "reset" that keyboard that I know of. slide the power switch until the green light comes on again and do the zap pram for 3 times, then let go and let the imac start up as usual. The keyboard should show up under the Bluetooth menu as a Bluetooth device, and then you can pair your iMac with it. and it should work, and the connection should be solid. Failing that, I'd suggest looking for any sources of interference, and making an appointment at your local genius bar/apple store and taking the magic keyboard in and explaining to them what's going on. Being polite is definitely helpful . You should have some kind of warranty on the Magic keyboard itself. I know on the iMac it's a year (longer if you bought AppleCare+). I've found Bluetooth keyboards to be kind of iffy and not so good for connecting and being able to use 'em right off the bat. That's why I have a nice big heavy solid "das Keyboard" which is USB. Anyways, make an appointment and take it in and talk to 'em.

john b