Board2

REISBOT Pump Guard

A small box that keeps a solar-powered water pump alive. Rust on a Raspberry Pi Zero W.

The problem

The pump is a 138 V, 1.5 kW DC brushless submersible (110–150 V range, 11 A max). Its own controller card is destroyed above 150 V. The array is three GSE-HC455 panels in series: 150.9 V open-circuit at 25 °C, and climbing toward 165 V on a cold morning — exactly the voltage present at sunrise, before any current flows. That killed the first controller card. The second time it could not be repaired.

What the box does

• Watches the array voltage and current every few milliseconds (PZEM-017 over RS-485).
• Keeps the contactor open until the array has settled inside the safe window (95–145 V), and drops it again on over-voltage, under-voltage, over-current, a dry well, or loss of contact with the meter.
• Waits, re-checks that the voltage is steady (about 15 s), and restarts by itself.
• Runs the pump from the water levels: a level relay in the well, another in the tank.
• Shows everything on a 20×4 LCD, one status light (blinking = ready, solid = running, two flashes = too high, three = too low) and a phone dashboard over its own Wi-Fi hotspot.

Parts

Repo layout

• rust/ — pumpd, the controller: state machine, PZEM-017 meter, front panel, LCD, watchdog, fail-safe, web dashboard. rust/src/bin/ holds two bench tools (failprobe, wdtest).
• kicad/level/ — the level-sensor board (schematic, PCB, etch transfers, drill file, wire-link map); kicad/render/ shows the finished board; kicad/BOM.txt is the sourcing list.
• hotspot/ — the Pi's Wi-Fi hotspot: setup script, captive-portal responder, watchdog units.
• fritzing/, qet/ — wiring sketch and electrical diagram.
• docs/ — enclosure layout and wiring pages; DESIGN.md and BUILD.md — design notes and build guide.

Disclaimer

This is a personal hobby project, built for one farm and shared as-is. It is not a product, it is not certified, and it is not affiliated with or endorsed by any employer or manufacturer. It switches 150 V DC, which can injure or kill: if you copy any of it, you take full responsibility for your own installation, and you should have a qualified electrician check it. No warranty of any kind — see the licence.

Licence

MIT