AT-09 BLE to UART notes

I picked up a couple of AT-09 Bluetooth to UART bridges for my solar at home project. Both the BMS and inverter have different grounds than the rest of the system, so rather than worry about isolating the signals I plan to send them over Bluetooth instead.

Solar limits

Something unexpected with my solar power setup: the cable loss is limiting the power produced by the panel, but it’s due to the voltage drop and not the power loss.

GPIO and Home Assistant

As part of moving my home server to solar power, I need a way of switching over to mains if there’s been a few grey days and the battery is getting low.


The HEYO BMS appears to be a DALY clone. My 8S 60A model has a selection of ports - on the top: NTC (3 pin) UART (6 pin) Unnamed 5 pin) On the bottom:


Adding remote control to a plain amplifier

Ausdauer: mechanical assembly

And that’s the end of the mechanical assembly. The differential went on fine, and the epoxy is strong enough to hold in the insets. There’s one last thing - I missed the insets on the end of the differential arm, so those are glued and curing

Ausdauer: assembled

I’ve almost completed the right hand side, and the left hand side is far enough along that I can assemble the whole rover!

Ausdauer: left rocker/bogie assembly

Progress update showing the new left hand assembly


I’ve released vedirect, a tool parses the Victron VE.Direct TEXT protocol and exports the metrics over Prometheus and MQTT. This can be used to monitor your solar installation and view statistics in tools like Grafana or Home Assistant.


I realized I haven’t posted about the current generation of nppilot, my never complete, often restarted rover project. The current version is a modified Traxxas E-Revo 1/16: Under the hood this is: