🚐 VW T5 Intelligent Split-Charge Management (V1.0)

A custom-engineered Power Management solution for VW T5 campers. Version 1.0 integrates an Arduino Nano with an LTC3780 Buck-Boost controller to solve the "low-resistance trap," protecting modern batteries from alternator surges via active current regulation and dual-rail telemetry.

T5 BSM V1.0: Features Hysteresis switching (13.4V/12.8V), a 3-second disconnect delay to prevent relay chatter, and a 30-second watchdog grace period for efficient power-down.

Get V1.0 Source Files

Arduino Code, Schematics & Data Logging Config

Full System Schematic & Management Architecture

Engineering Focus: The Low-Resistance Trap

Modern AGM, Gel, and Lithium batteries have significantly lower internal resistance than legacy lead-acid units. When directly bridged to a T5 alternator via a standard relay, they pull massive current—often exceeding 30A—overloading vehicle wiring and risking thermal damage to the battery plates.

This system acts as an intelligent current-limiter, capping the charge at a safe 14A while maintaining a stable 14.4V profile regardless of alternator load.

Safety & Reliability: The NE555 Watchdog

To ensure zero parasitic drain when the engine is off and to protect against software hangs, we utilize an NE555 "Missing Pulse" Detector. The Nano sends a 1Hz heartbeat; if this heartbeat stops due to an engine shutdown or a software error, the watchdog physically cuts power to the module after a 30-second grace period, allowing for a final log to the SD card.

V1.0 Logic & Charge Stages

📸 Prototype & Operations

**Normal Operation (Charging)**	**Physical Build**
Display shows the current mode of operation which is 'Charging', the health of the SD card and the number of data points logged since ignition start, the health of the Real Time Clock with current Date and Time, the voltage and current of the Leisure Battery, the Voltage of the Alternator, and the internal unit temperature.	Image shows the internal hardware architecture of the Prototype unit, including the Arduino Nano, LTC3780, and safety watchdog components.

🗺️ Future Roadmap

• Solar Integration: Adding an MPPT charging rail to balance power between the Alternator and Solar panels.
• Bluetooth Dashboard: Integration of an HC-05 module for real-time smartphone telemetry.
• LiFePO4 Profiles: Expanding the state-machine to support Lithium Iron Phosphate voltage tolerances.