Unexpected Maker development boards ship with the ability to power your projects from a single cell LiPo battery, and to also charge that battery when you connect a 5V power source.
When the battery is connected, and you connect a 5V source via the 5V pin, or the USB connector, the battery will start to charge, and will stop powering the board, so you don’t get into a charge/discharge race 🙂
When your battery is charging, the yellow CHRG LED will light up and stay solid. Once the battery is full, the CHRG LED will turn off.
By default, the charge rate of the charge IC (PMIC) is set to approximately 300mA (using a 3K3 resistor).
The PMIC can charge up to 500mA, but this requires changing a resistor on the board – not really recommended unless you really need the faster charge rate, and you are skilled at removing and adding 0402 sized surface mount components.
Here is a table of PMIC charge rates based on resistor value:
| Resistor Value 10K | Charge Rate 110mA |
| 5.0K | 200mA |
| 3.3K | 300mA |
| 2.32K | 500MA |