Choosing the right polymer lithium (Li-Po) battery for an IoT device is a balance between runtime, form factor and cycle life. In this guide we walk through the four key parameters every hardware engineer should specify before issuing an RFQ.
1. Estimate average current draw
Compute the average current as the weighted sum of active and sleep currents. For a typical LoRaWAN sensor reporting once per hour, average current is often 50-150 µA.
2. Add 25% headroom for ageing
Li-Po cells lose ~20% capacity by cycle 500. Spec the nominal capacity 25% above the runtime requirement so the device still meets its target at end-of-life.
3. Match the temperature range
Standard Li-Po operates -20°C to +60°C in discharge, but charging below 0°C is not allowed. If your device must charge in cold environments, ask for a low-temperature variant.