LiPow Features

• Charges and balances 2s-4s packs (single cell charging possible in future)
• USB type C input
• Supports charging up to 60W from USB PD power supplies or any other USB C port with PD source capability (such as a Thinkpad X1 laptop)
• Supports non USB PD power supplies (limited to 2.5W - 5V, 0.5A)
• Automatically reduces charging power as device temperature increases
• Charging is done through an XT60 connector and has JST XH connectors for balancing 2s-4s packs
• User feedback through an RGB LED
• Open source schematic, BOM, and firmware
• SWD and UART breakouts for firmware development
• UART command line interface for debugging and run time information

User Guide

• Plug into any USB C power supply/wall wart/device that supports power output
• Plug in the balance plug from your 2s-4s battery
• If the LED turns blue, the battery needs balancing and balancing is active
• If the LED turns green, the battery is balanced
• Now plug in the XT60 plug from your battery
• If the LED turns red, the battery needs charging and charging is active
• If the LED turns green, the battery is charged and balanced
• Balancing and charging can be active at the same time and both the red and blue LEDs will be on
• Charging will only start when both the balance and XT60 plugs are connected
• If a damaged pack is attached, charging will stop if any cell rises above 4.21V
• If any cell is below 2.7V it will not charge or balance

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.

Case

• Two different 3D printed cases are available. One fully enclosed for everyday use and one with an opening for programming and debug connections.
• 3D printed case assembled/kit includes light pipe for LED and 3 M3x0.5 18mm long hex button head screws
• Aluminum case soon to be available. Case will act as heat-sink and improve charging performance.
• STLs are available for 3D printing your own case.
• Onshape case source file available here.

Hardware Specifications

• STM32G071CBT6 microcontroller with built in USB PD Phy
• BQ25703ARSNR programmable regulator (could be used as programmable power supply in future)
• IFX25001MEV33HTSA1 3.3V regulator supporting up to 45V input
• USB Type C connector power input
• XT60 connector for charging
• JST XH connectors (3, 4, and 5 pin) for balancing and pack cell count detection

Tested with these USB PD Supplies

• Lenovo Thinkpad 65W Charger
• Lenovo Thinkpad X1 Carbon USB C Port
• Anker PowerPort Atom PD 1 30W
• Aukey PA-Y8 27W Turbo Charger
• Nintendo Switch Power Supply
• Generic 2.5W USB A Wall Wart

Sample of the CLI