Van Hub

Every part of the van’s power system has its own app, and none of them talk to each other. The van hub is an ESP32-C3 SuperMini in a 70 x 23 mm printed box that listens to all of them and serves one page at van.local on the van’s Wi-Fi. No app and no cloud: it’s a web page saved to the phone’s home screen.

What it reads

• Victron chargers and shunt: their Instant Readout broadcasts, which are encrypted Bluetooth advertisements. Nothing connects and nothing is wired; each device’s key is pasted in once on the setup page.
• Renogy battery: the hub connects to its Bluetooth BMS every 30 seconds, reads voltage, current, charge and each cell, and lets go.
• Temperature: Govee H5075 thermometers, from their broadcasts. The Govee app keeps working alongside.
• Water: the water flow meter, by wire.
• Roof fan: the MaxxFan controller, over Wi-Fi. The hub can open the lid, set the speed and show the motor’s graphs.

Water, then and now

The water used to be counted by an Arduino Uno with a little LCD, running the stock flow-sensor example at 450 pulses per liter against a 25 gallon tank. It kept the count in memory only, so every time the power dropped it decided the tank was full again. The hub keeps the same sensor but saves the count through power cuts and has a Tank filled button.

A flow meter is still dead reckoning, good to about 10 percent. Measuring the level itself is the next step: a submersible pressure probe on the tank floor for a real reading, or stick-on level switches on the outside of the plastic tank.

The box

The box is printed in PETG, base and lid on one plate (15 g, 34 minutes). The ESP sits bare on a pedestal with its USB-C port in the end wall, where the 12 to 5 V converter plugs in. The sensors plug in at a 3-pin JST-SM connector just outside the box, so the flow meter comes off without opening anything.