I've just checked out this thread after massive frustration, losing connection repeatedly - every few secs - then realised my iphone was on the desk, about a foot away! Have moved it to the other side of the room and now only losing connection about once every few minutes. So it really looks like other wireless devices are a big factor in this prob.
Shall go and bury the iphone in the back garden in a mo, to confirm the prognosis...
Sound like my issue with the magic mouse. I notice the indicater green light was off when i lost lost my connection. Once I reinstalled the batteries the light would glow and my connection was temportarly restored. After losing my connection again; I reseated the batteries but I added a small cushion of folded paper. I made sure my cushion wasn't too thick so to allow for the battery cover. After my small mofication my mouse has not lost connection for over several weeks.
I have been so frustated with the intermittent disconnects that I did my own investigation. The best clue was that different battery brands reacted differently.
I think people are chasing mostly red herrings. Nothing to do with bluetooth or other RF signals or software.
The answer lies in the battery compartment design, specifically in the depth of the hole for the positive battery terminal. In trying to be clever (to prevent wrong polarity insertion?) apple screwed up and made the hole fractionally too deep, i.e. the mouse positive contact is too far down the hole for some batteries.
Some of you are correct, that AA batteries are not all the same size. the critical dimension is the height of the positive terminal above the inner battery shoulder at the +ve end. ( inner because most batteries have slightly conical shoulders).
The longest protrusion of the positive terminal from the shoulder is found on the Energizer lithium and the Ikea, which have non conical shoulders and usually make contact if you don't bang the mouse around too much.
The shortest protrusion of the positive terminal from the shoulder that I have found is on the Duracell Ultra Power, which also has the most conical shoulder..
If Apple had reduced the depth of the well for the +ve terminal by just 1mm, all batteries would fit and work.
FYI, a few measurements of the +VE terminal length above the inner shoulder flange:
Energizer Lithium: 1.6 mm
Ikea: 1.6 mm
Ace: 1.4 mm
Duracell Ultra Power: 1.2 mm
Ok, so I just noticed something. I replaced the batteries (non-rechargeable) ones with freshly charged rechargeable batteries. However, I noticed the connection was still being lost. But then something interesting happened. I set my cup of water on my desk next to my mouse, and then it says "connected" ... hm.. So it went to "Not connected" about 4 secs later. So I then shook the desk next to the mouse and it connected again...
Theory: I think Apple made the mouse where, to save battery life, when idle, it disconnects. It's probably an error that is disconnects after only a few seconds or perhaps they thought it would re-connect at a faster rate. Anyhow, I think this is a flaw in the design.
Solution: Have 2 sets of rechagrable batteries and swap often.
...that's just my 2 cents and I hope it helps.