I've also experienced the battery drain problem. I went to my parents cabin where they don't have even a proper gsm signal available. I noticed that my battery was running low very quickly. I thought it was because of the low signal so I decided to turn the device completely to offline mode. It had no effect whatsoever to the rate of the drainage.

I don't have fmms installed, never had.

My brother has also experienced the same problem. And I think it was before he even decided to start using devel and test repos.

I think this problem doesn't have anything to do with devel or test repos software, neither low signal levels. I think it's some major bug within the OS that's triggered randomly. Usually reboot is enough to stop the drainage. Sometimes it feels like the drainage starts right after the reboot!