Energy usage & Battery

Power options for the Fencyboy sensor and battery life

You can power the Fencyboy sensor using one of several energy sources, and you should choose the one that is most suitable for your conditions. In general, the sensor consumes very little energy because it is heavily optimized for low-power operation but still requires some energy for processing and wireless transmission of the data. You can always replace the battery by yourself using normal tools.

1. Single-use Battery: with a runtime of more than 3 years thanks to a special outdoor IoT battery that's specifically designed to withstand extreme temperatures. We use Lithium Thionyl Chloride (Li-SOCl2) Batteries with a nominal voltage of 3.6 V and a capacity of 16 Ah to 19 Ah in a single size D cell.

   1. AA Lithium batteries: can be used for seasonal operation of the Fencyboy with a lifetime of 6-12 months. You will need two AA lithium batteries with a nominal voltage of 1.5 V and a capacity of 3000 mAh. This can be very useful to monitor fences used in the mountains, like the Swiss Alps.

2. Solar Powered: with a small rechargeable battery to power Fencyboy throughout the night and keep it running in weeks of darkness. We use a lithium iron phosphate battery (LiFePO4) battery that gets charged using a outdoor rated small solar panel mounted on the outside of the enclosure. The battery has a nominal voltage of 3.2 V and a capacity of 600 mAh within a single size AA cell.

Solar panel + rechargeable battery

Big single-use battery

Small single-use batteries

The lifetime of a certain battery can not be predicted with 100% accuracy from the beginning because there are many random factors impacting the lifetime. You can do something about some of them to obtain a longer battery life.

1. LoRaWAN link quality has a major influence on the energy consumption because the device will use more energy if the quality is bad to reach a gateway that's far away. This factor may change dynamically, and the device will adapt to the conditions using LoRaWAN Adaptive Data Rate (ADR).

2. Outdoor temperature has a similar effect on battery life. If it is too cold (especially below -10°C) or if it is too hot (especially more than +40°C), you'll see an increase in energy consumption of the Fencyboy. The system is still going to work fine in these conditions, but be aware that battery lifetime gets reduced. After all, the Fencyboy sensor is built for outdoor operation and works much better than indoor sensors.

3. Electric fence properties such as the frequency of energy impulses or the general on/off state influence the energy consumption as well. The frequency is generally limited to 1 Hz by law, but some energizers reduce the frequency to, e.g., 0.33 Hz (every 3 seconds) to save energy. Additionally, having the electric fence off (the energizer is turned off) will put Fencyoby into a power-saving mode as well, but it will still transmit regularly that the fence is still off (see Smart Sleep).

The Fencyboy sensor integrates a precision battery monitoring system to monitor not only the battery cell's voltage but also the current going out of and into the battery. This is done using a battery fuel gauge and lets you see the remaining capacity of the battery in mAh before it is empty. Not only is this useful to predict when the battery needs to be replaced, it is more or less necessary since monitoring just the voltage of a Li-SOCl2 or LiFePO4 battery yields very little insight about the actual state of charge because the voltage stays rather constant for a very long time. Many other IoT sensors used with LoRaWAN or other wireless technologies do not have a fuel gauge chip and rely on voltage measurement.