Loren Lisk
A Choice for Energy Idependence
DIY Powerwall
The batteries live in one of the two matching 30U racks described on the homelab page (the other still runs the lab). Watching them meant teaching a computer to read the battery management system.
Watching the pack
The pack is managed by a Batrium Watchmon 4+ BMS, which broadcasts its telemetry as little-endian binary UDP packets on port 18542.
batrium-udp2http-bridge is a Go service that turns those packets into something easier to use. It listens for the broadcasts, picks a decoder from the 16-bit message type in each packet, and keeps the latest decoded message for each type. Each type is served as JSON on a route named after its message ID (for example /0x3E32), plus a per-cell-monitor route, /0x4232/{id}. It also exports Prometheus metrics and ships as a Docker image.
| Message ID | What it carries |
|---|---|
| 0x5732 | System Discovery |
| 0x415A | Cell Monitor Basic Status |
| 0x4232 | Cell Monitor Full Info |
| 0x3E32 / 0x3F33 / 0x4032 | Telemetry Rapid / Fast / Slow |
| 0x4732 | Logic Control Status |
| 0x4932 | Remote Status |
| 0x5432 | Daily Session |
| 0x6131 / 0x7857 / 0x5632 | Communication Status / Shunt Metrics / Lifetime Metrics |
| 0x4A35 / 0x4B35 / 0x4C33 / 0x4D33 / 0x5334 | Hardware setup: system, cell group, shunt, expansion, integration |
| 0x4F33 / 0x5033 / 0x5158 / 0x5258 / 0x4E58 | Control-logic setup: critical, charge, discharge, thermal, remote |
- Jan 2019 - Started as batrium-udp-listener, renamed to batrium-udp2http-bridge in Dec 2019
- Apr 2021 - Prometheus metrics output added
- Through Jan 2024 - Dockerfile vulnerability fixes
The source is on GitHub: github.com/liskl/batrium-udp2http-bridge.
Before the batteries: watching the meter
In Feb 2014 I wrote TED5000.sh, a shell script that cron runs every minute. It pulls the latest power reading from a TED 5000 whole-home power monitor gateway and feeds an rrdtool round-robin database: a 60-second step, a GAUGE data source, and a MAX archive of 525,949 one-minute rows (about a year of minutes). It then renders PNG graphs, which the old site served.
* * * * * TED5000.sh <gateway-ip> 0rrdtool create <rrd-dir>/ted5000.rrd --start now --step 60 DS:watts:GAUGE:120:0:20 RRA:MAX:0.5:1:525949The script and setup notes are on GitHub: liskl/t5k-power-monitor.
Years later, the same itch became the powerwall.