id also second the use of 18650s

@antonholmstedt a pro mini fits if you cut the corners, check out https://forum.mysensors.org/topic/6612/door-sensor-remix-of-some-mys-community-efforts

In deep Sleep the cunsumption is below 19µA, but i have to send with PA_MAX. On some Windows the open/close frequency is verry high, so the battery is to fast emty. The CR2032 is good, but i want more "lifetime"