Nestbox Power Management

Power is supplied to the system via 4 rechargable NiMH batteries (Type IKEA “LADDA 2450” or Eneloop Pro) with a 2450mAh capacity. Fully charged, each cell has a voltage of about 1.4V. During most of its life time, the cell is at its rated voltage of 1.2V and will drastically get discharged when reaching 1.1V. To avoid permanent damage, it should never get discharged below 0.8V

Battery change

How fast a battery gets discharged depends a lot on the external conditions and on how many times an owl sat on the perch. Generally, the RFID reader consumes the most power. Generally, one should expect a system runtime of 2 up to 6 months.

It makes sense to replace and recharge the batteries of a smart nestbox as soon as the total battery voltage is at 4.4V or below.

Undervoltage Protection

To protect the batteries from long-term damage, the smart nestbox turns off all running systems (i.e. weight measurement and RFID reader) as soon as the total battery voltage reaches 3.6 V. To prevent accidental shut downs, the measurement is performed six times in intervals of 30 seconds.

Current prototype does not feature power harvesting capabilities. Batteries must be changed and recharged regularly.