45kWh 18650 DIY Powerwall + 9kW Solarpower in Germany + WiFi DIY BMS


New Member
I was allowed to film a friend's solar system. For plant is quite exciting, so I have added extra English subtitles for you. He uses 5600 18650 cells with the diy BMS from my channel and a mpi 5k (mppsolar).

DIY Arduino BMS:
The BMS is developed by myself and is based on an Arduino D1 Mini module on each 18650 pack. So at 14s then 14 Arduino modules.
These are supplied by the packs themselves and have no other connection anywhere. So I can take down a pack and the BMS just goes with it. That's pretty handy for maintenance. Here is a wiring diagram for 1 BMS Module
In more detail:

The BMS modules then all send via WiFi to a RaspBerry PI, which then evaluates everything for me and displays it on Grafana.
If any voltage is wrong or temperature is too high, then a Finder relay is switched and the entire battery is disconnected. This works extremely well so far.
And best of all, it's pretty cheap.



Solar Enthusiast
Using that D1 is awesome...$2/cell!

Do you have documentation on GitHub or something? I’ve been a bit frustrated with finding a BMS to do what I want it to and this looks...promising.