ProxiCharge

Nov 2023 - Jul 2024

Proximity-Based Charger Safety System that automatically powers off unattended chargers.

Overview

ProxiCharge is an automated charger safety system that prevents unattended charging of lithium batteries by monitoring room occupancy and shutting off chargers when no motion is detected.

How it works

Initial setup: press the power switch on the motion detector to enable chargers.
Motion is monitored by three PIR sensors. While motion is detected the system keeps chargers enabled and shows a green status.
If the room is vacant a countdown begins (configurable; default ~5 minutes). Visual and audio alerts escalate before shutdown.
If vacancy persists past the timeout, the motion detector sends an ESPNOW “OFF” command to the remote power-supply controller which cuts power to the chargers.
Returning within the timeout resets the countdown; otherwise the user must re-enable the system.

Features

Motion detection (3x PIR sensors)
Remote control of charger power via ESPNOW
Visual (RGB LED ring) and audio (buzzer) alerts during countdown
OTA firmware updates for the motion detector

Technical Details

Components

Motion detector: 3 × PIR sensors, ESP32-S2 (Lolin S2 Mini), RGB LED ring, buzzer, power switch.
Remote power controller: ESP32-S2 controlling a relay and a 24 V SMPS to switch charger power.

Design

Enclosure and mounts modeled in Autodesk Fusion 360 and 3D-printed for the PIR sensor assembly.

Programming

Firmware written for the Arduino/PlatformIO environment targeting ESP32-S2. Uses esp_now for low-latency local wireless commands and simple heartbeat/timeout messaging.

Final results

The prototype demonstrates reliable occupancy-based shutdown of battery chargers and includes photos, CAD renders and circuit diagrams in the repository.

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