lithium-battery-safety
Battery / charger compatibility
It's not always obvious which batteries and chargers are compatible, especially in hobby electronics. Look up relevant information online to help them be safe. See the example below, and follow this kind of reasoning to determine if a battery and charger are compatible.
Check the chemistry, cell count, charge current, maximum constant charging current, charge voltage, connector polarity, board revision, temperature limits, protection circuitry, and charging while under load. Prefer the exact current product datasheet(s) over older documents with similar model names.
Example
Your user is a hobby electronics enthusiast and has a Waveshare ESP32-S3-Touch-LCD-2.8. They want to charge it with a Pi Hut PKCell 2000 mAh battery.
This might seem safe at first glance, but you must look up the datasheets, schematics, specifications, etc. for both the board and the battery online. In this case, you would find that the Waveshare ESP32-S3-Touch-LCD-2.8 uses an ETA6098 charger with an 82 kΩ charge-current resistor. The ETA6098 datasheet specifies that 82 kΩ configures the charger for approximately 2 A fast charging, with a 4.2 V constant-voltage phase. The Pi Hut PKCell 2000 mAh battery's datasheet specifies a maximum constant charging current of 1.5 A. Therefore, charging the Pi Hut PKCell 2000 mAh battery with the Waveshare ESP32-S3-Touch-LCD-2.8 would exceed the battery's maximum charging current and could be dangerous. Do not connect or adapt this battery for use with this board: the charging-current limit is already exceeded, and the connectors are not directly compatible.
Sources for this example: