For some time now I have been looking for an open source USB-C Powerbank. I didn't find it so I started my first project.
Preliminary characteristics:
- 1 quality USB-C connector
- USB Power Delivery 3.0 dual role
- Certified integrated solution
- Source, 5 to 20V, max 45W
- Sink, 5 to 20V
- Li-ion charger
- Buck / Boost
- Programmable
- Rated charging current, 1.5A
- For 4 cells (4S)
- BMS
- Programmable
- Smart fuel gauge (battery health)
- All protections (Under Over Temp, Under Over Voltage, Short-Circuit)
- Cell balancing
- Management by microcontroller
- Low power
- I2C / SMBus hardware
- Maybe integrated into the Power Delivery Controller
- Possibility to use the battery voltage (Vbatt) to power external projects.
- 4x quality 18650 cells
- Open Hardware Licence CERN-OHL-W (weakly reciprocal)
Preliminary synoptic:

I will be happy to discuss this project with you!
one small question: I have some battery/acumulators old and new. old have small capacity/size.
Is possible using old and new battery in one time? For example put power to one, net to second, thirth etc.
I would like to put solar panel, battery for my raspberry pi. And using big 12V AND AA recachable AND 18650 etc. And replace/changing in working computer.