I am working on a project using a 5v Arduino Pro Mini. To save power I have it power down and wake up every about 15 minutes to check on the battery strength and then power down again. This cycle runs 8 times when I have it wake up and then run through my main code, checking sensors and then handing those reading off to an ESP8266-1 to send the information to Adafruit.
I have built three units using the same components/configuration and the exact same code. On one of the Arduino Pro Minis the elapse time is about 1hr 55min. on another it is about 1hr. 56min. 30seconds while the third is about 1hr. 59min. 50seconds. Why is there a difference between the three. I can understand being a few seconds different based on how fast the ESP8266-1 connects to the internet and transmits the data but a difference of 4minutes I don’t understand.
Can someone explain why this happens? Or should I be posting this somewhere else.
Thanks.