1 year with batteries - temperature sensor project
|Temperature sensor with alkaline batteries|
voltage came down to 3.34 volts and this is a point where the low dropout regulator (MCP1700) keeps quit working sometimes even when the load is only about 25 mA every four minutes when the XBee (end device, sleeping) sends the temperature data to the coordinator.
|Voltage development temperature sensor|
Why did I use used battery cells and not new ones? Because they were lying around and I was wondering how long some spare, already used cells would last during time and different weather conditions. And they lasted almost one year!
The temperature sensor is located outside and we had temperatures of around -15 to +30°C during the year. The chart you see is far from scientificly accurate but gives you a raw picture of the voltage curve for those cells (GP super alkaline).
Next I will replace the batteries with some rechargeable batteries. There are some nice energy harvester ICs on the market - maybe this will be the next power supply for my sensors. Stay tuned.