Open Source hardware and software for 2S-4S Battery Controller
Note I have only just begun work on this the week of Christmas 2025. I am uploading schematic Rev. D0 and making this public so that hopefully people start seeing it and joining Discord. Once I am done with the design and have PCB returned things will get a lot more interesting. Rev D0 implies it is not complete so there are likely errors. Any feedback on features people would like to see that don't seem supported, make an issue or chat about it in Discord!
When working on powering a mobile embedded open source project I realized there seemed to be a gap in the available open source hardware out there for making a USB-C power pack/power bank. Most projects focus on a smaller single LiPo or are focused on the substatially larger homewall type applications. Instead, this PCBA allows you to make a 2S-4S battery pack with fast charging and very high output power capabilities that can be easily be embedded in a design. The original vision was for supporting Raspberry Pi5 based systems but that is not where it has to end.
The philosphy has been simple: leverage USB-C PD for input charging (and output on some versions) and provide maximum flexbility while trying to control costs as best as possible.
The PCB will be designed such that it should be possible for PCBway, JLCPCB and others to fabricate it. Assembly for most people is also best handled by someone like PCBway or JLCPCB unless you are very experienced working with hot air tools.
Always remember it'll only ever be as good as the batteries you put in it! While many applications may be able to use the cheapest batteries, if you intend on pushing the output hard you need to ensure you use high quality batteries otherwise you may not get what you are looking for.
OPP-100-5-NPD
USB-C PD 100W Charging
2S-4S Pack Topology (Parallel Depth tbd)
5V-24V Regulated Output Voltage
5A Output Current Limit
100W Output Power Limit
USB-C Output Connector (Non-PD)
OPP-100-10-TJ
USB-C PD 100W Charging
2S-4S Pack Topology (Parallel Depth tbd)
5V-24V Regulated Output Voltage
10A Output Current Limit
100W Output Power Limit
TJ0211 Output Connector
OPP-100-5-PD
USB-C PD 100W Charging
2S-4S Pack Topology (Parallel Depth tbd)
5A Output Current Limit
100W Output Power Limit
USB-C PD 100W Output
OPP-240-24-TJ
USB-C PD 240W Charging
2S-4S Pack Topology (Parallel Depth tbd)
5V-48V Regulated Output Voltage
??A Output Current Limit
240W Output Power Limit
TJ0251 Output Connector
OPP-240-5-PD
USB-C PD 240W Charging
2S-4S Pack Topology (Parallel Depth tbd)
5A Output Current Limit
240W Output Power Limit
USB-C PD 240W Output