Secure DIY Garage Door Opener
QCPete 
Power Considerations
In order to save power on the remote control, I opted to put a momentary push button in series on the power input. This way, power would only be connected when I wanted to open the garage door. Otherwise, it would remain completely off. Also, with a more traditional DPST switch, we'd be more likely to accidentally leave it switched on and drain the battery. Luckily, the ProRF has a couple headers already in the design for an external switch.
Now I wanted to consider how much power is actually being used during each attempt to open the garage door. I hooked up an SparkFun RedBoard Artemis and a Zio Current and Voltage Sensor - INA219 (Qwiic), and I had some data streaming in no time!
Here is what a complete cycle looked like on the serial plotter and monitor:
Each reading is precisely 100ms apart, so adding them all up I can see that it will use 0.065mAh per cycle.
21 readings (2100ms) at 36mA = 0.021mAh
1 reading (100ms) at 56mA = 0.002mAh
20 readings (2000ms) at 76mA = 0.042mAh
Total: 0.065mAh
Battery capacity is 400mAh
400mAh / 0.065mAh = 6,153
So according to my rough math, I think I can press this button 6153 times with this single battery. At 2 times a day, 300 days a year (600/year), that's 10 years. Even with capacity loss during storage in my car (let's say 10% each year), it'll still should last... let's see...
Year: capacity : -10% - yearly use for cycles (600 * 0.065 = ~40mAh)
Year 1 : 400 - 40 - 40 = 320
Year 2 : 320 - 32 - 40 = 248
Year 3 : 248 - 25 - 40 = 183
Year 4 : 183 - 18 - 40 = 125
Year 5 : 125 - 13 - 40 = 72
Year 6 : 72 - 7 - 40 = 25
Wahoo! Six years is pretty good. Now I just need to make sure it doesn't get squashed somewhere in my car.