This project was developed as a final year engineering project for a friend, with embedded system logic written and optimized by me. It is a custom Battery Management System (BMS) for a 3S 12V 80Wh lithium-ion battery pack, focused on safe and intelligent fast charging, thermal protection, and cell health tracking.
I designed and implemented the core fast charging logic and sensor-based safety protocol using an Arduino Nano. My optimized power delivery profile ensures safe and efficient battery charging across different charge levels:
| Battery Charge (%) | Charging Power |
|---|---|
| 0% to 50% | 200 Watts (Max) |
| 50% to 80% | 150 Watts |
| 80% to 90% | 100 Watts |
| 90% to 100% | β€ 50 Watts |
This tiered charging protocol protects the battery from overheating and overvoltage damage, especially in the final 10% where lithium-ion cells are most sensitive.
| Feature | Description |
|---|---|
| π Fast Charging | Charged a 12V/80Wh battery at 200W with intelligent tiered cutoff logic |
| π‘οΈ Thermal Protection | Used analog temperature sensors to halt charging if temp > 50Β°C |
| βοΈ Cell Balancing | Voltage readings from 3 cells used to detect imbalance |
| π§ Degradation Tracking | Estimated degradation from charge cycles and voltage drop over time |
| π Safe Charge Control | MOSFET/Relay switching based on sensor data |
| Component | Purpose |
|---|---|
| Arduino Nano | Core controller running the BMS firmware |
| Current Sensor (ACS712) | Measures charging current |
| Temperature Sensors (NTC) | Reads battery thermal data |
| Voltage Divider Network | Measures individual cell voltages |
| MOSFETs / Relays | Switches high-current paths |
| 3S Li-ion Battery Pack | 12V / 80Wh test battery |
- Real-time voltage & temperature sensing via ADC
- Logic:
if temp > 50Β°Cβ Stop chargingif cell voltage > 4.2Vβ Stop chargingif ΞV > 0.1V across cellsβ Slow down charging
- Adaptive power levels based on charge percentage
- Real-world fast charging control
- Battery safety + embedded power management
- Multi-cell monitoring and logic control
- Lithium-ion battery care principles