bluetooth keyboard

I've noticed that my 3 year old bluetooth keyboard no longer likes the apple rechargeables. I'm not sure if there is an OS issue (10.10.1) or if the sleep circuitry is messed up or something else but rechargeables that used to last a month now show up as having 2% or so left in less than a week. I put the same in the mouse and the mouse seems to think it still has more than 70%. If I put in brand new disposables, the keyboard/OS seems happy and continues to report high levels of life.