JPBMS - My open source solar battery charger

1

Hey all, thought I’d pop in and share a project I’ve worked on this summer, my custom lithium ion BMS + solar charger.

https://github.com/jakepoz/jpbms/

Fully open-source hardware+software.

It currently supports a 3S lithium ion battery and a ~24VDC solar input, and it does basic MPPT tracking, charging, and balancing. The idea is that it has a low quiescent current ~100uA (and I want to push it lower), and that it would top-up the battery on an outdoor robot project that’s running off of hobby-style motors/electronics otherwise.

I’d say it’s mostly a learning project for me at this point, and nothing here is particularly groundbreaking. But one thing that’s cool about it is that it’s not using any ICs beyond a standard microcontroller. So the charging is implemented by hand PWMing the input switches on an inductor. The key here is that it will still be manufacturable in 5 years because it’s not depending on any hard to find or custom components.

Code is in C based on libopencm3, Schematics are available in KiCad, and Manufacturing files for JLCPCB are also present. It would cost around $150 to build and ship 5 boards from there.

Hope you like it, happy to share more and answer any questions.

2

Hm, I’d check it out but Github says 404 on that link. Is it still marked as private or something?

3

Oops, fixed, should be public now.

4

Cool, looks neat! I’m an STM32 fan myself. I doubt I’ll have any time soon to give it a deep dive, but it’s something I’m going to keep in the back pocket for one of those bursts of “hey let’s fiddle with something” energy that come around from time to time. This is right up my alley of usefulness.