Projects / Electrical / Electrical project 8

Battery Management System (BMS) for a 4S Li-ion Pack with Cell Balancing

Approx. component budget: Rs. 6,000 - 10,000

Objective

Build a BMS that protects a 4S pack and balances the cells, then check how well it keeps the cells within a small voltage spread.

What you will build

A 4-cell Li-ion pack with a voltage-sensing and balancing circuit, a microcontroller, over- and under-voltage cut-off MOSFETs, temperature sensors and a display.

Results you can expect

• Cell voltage vs time during charge and discharge
• Balancing effect on voltage spread
• Cut-off thresholds tested
• Temperature rise
• Estimated state of charge

What you will learn

Battery behaviour, protection and balancing, and state-of-charge estimation, key topics in EV and storage industries.

Tools and notes

Arduino/ESP32, MOSFETs, INA219, thermistors, Excel. Li-ion cells can catch fire, so use protected cells, a fuse, a fireproof tray and a low charge current.

Resume points from this project

• Built and tested Battery Management System (BMS) for a 4S Li-ion Pack with Cell Balancing; objective: build a BMS that protects a 4S pack and balances the cells, then check how well it keeps the cells within a small voltage spread.
• Measured and analysed cell voltage vs time during charge and discharge and balancing effect on voltage spread; wrote the report and presented the results in a viva. Add your own numbers: [x].

Replace [x] with your own measured results. Write only what you really did.

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