I have a device in my flowerbox where I monitor soil moisture. The device requires about 3.3 v (it's an Arduino pro mini with an ESP8266).
The device is running on 3 x AAA-batteries (should be 3.6 v)
The device runs a cycle of:
- Powering on ESP and Sensor
- Collecting sensor data
- Transmitting it via WiFi
- Powering off ESP and Sensor
- Sleeping 20 minutes
It's been running fine for almost 75 hours, then it started continuously restarting.
I measured the voltage of the batteries. They were 2.86 v. Then I waited 5 minutes, measured the voltage. Now they were 3.1 v. I thought this problem might be caused by low outside temperature. I stuck the batteries in the fridge for 20 minutes, then tested them. They were 3.1 v.
So question is: How come the batteries voltage change that much?
Best regards Frederik