Open-source ESP32 firmware

Know what your Victron Blue Smart charger is doing — at a glance, all winter.

A tiny gadget that reads your charger over Bluetooth and shows it on a little screen, a web page on your phone, and in Home Assistant — for a car, motorcycle, or boat battery.

The firmware is free & open-source — you just bring your own ESP32 board (from ~€5).

Flash a board I already have one

Needs a compatible ESP32 board, a data USB cable, and desktop Chrome or Edge — no app to install.

Reads Victron Blue Smart chargers with “Instant Readout” (charger firmware 3.61+, check in the VictronConnect app). Supported chargers & boards →

WinterDash dashboard in demo mode — a live charge cycle with the voltage climbing

Features

What it does.

Live charger readings

Voltage, current, and charge stage (Bulk / Absorption / Float) read straight from the charger's Bluetooth broadcast. Nothing wired to the charger.

Your own banner

Put your actual car, motorcycle, or boat on the screen — the built-in converter turns any photo into a banner, right on the device.

Web & Home Assistant

Open a web page from your phone on your own network — and it shows up in Home Assistant automatically, no key to enter.

Cheap hardware

Runs on a €5–25 ESP32 board you can buy anywhere. No proprietary hardware, no subscription.

Free & open-source

GPL-3.0. No account, no cloud, no telemetry — everything runs on your own device, on your own network.

Demo mode

A realistic charge cycle plays with no charger connected, so you can try the whole thing before you pair anything.

Supported boards

Flash a ready-made build in a minute.

TTGO T-Display · 16 MB

Color screen + 2 buttons. The main, recommended board.

Docs → Install →

CYD · 2.8″ touch

The roomiest screen — a 2.8″ touch display, all in one board.

Docs → Install →

Screenless ESP32

No screen — a status light plus the web dashboard. The cheapest build.

Docs → Install →

TTGO T-Display · 4 MB

Same screen, the cheaper 4 MB variant.

Docs → Install →

You pair the charger once, with a code from the VictronConnect app — no soldering, no wiring to the charger. Which board? Prices & where to buy →