LiPow - Lipo battery charger with USB type C and power delivery

• Charges and balances 2s-4s packs (single cell charging possible)
• USB type C input
• Supports charging up to 30W without a heatsink and 60W with a heatsink (aluminum case coming soon)
• Charging is done through an XT60 connector and has JST connectors for balancing 2s-4s packs
• User feedback through an RGB LED
• Open source schematic, BOM, and firmware
• SDIO and UART breakouts for firmware development
• UART command line interface for debugging and run time information

The device will be pre-programmed with a fixed max current limit of 3.5A. Everything runs automatically and will charge up to the max capability of the connected USB PD power supply if the max current output limit exceeds the input power supply. Lower current limits can be programmed as well.

Charging current is decided by the USB PD Source capability. First, it checks the available voltages from the source, then selects the voltage that will result in the highest efficiency for the regulator based on the number of cells. For instance, using a 30W supply with a 20V 1.5A (30W) capability and a 4s Lipo battery at 15.0V. The charging current will be 30W/15.0V=2A. As the battery voltage increases, the max charging current will decrease. 30W/16.0V=1.875A.

Sample of the CLI.