Projects / Electrical / Electrical project 77

Battery Capacity and Internal Resistance Tester

Approx. component budget: Rs. 4,000 - 7,000

Objective

Test and grade used batteries by capacity and resistance for reuse in power banks and lights.

What you will build

A constant-current discharge tester that logs voltage and capacity, and measures internal resistance with a short pulse, for 18650 or lead-acid batteries.

Results you can expect

• Capacity in Ah for 10 cells
• Internal resistance in milli-ohms
• Capacity vs discharge rate
• And grading into good
• Usable and reject groups

What you will learn

Battery testing, discharge curves, internal resistance and safe handling of cells.

Tools and notes

Programmable load (MOSFET + shunt), ESP32, INA219, thermistor. Never over-discharge or short cells and always test in a ventilated, fire-safe tray.

Resume points from this project

• Built and tested Battery Capacity and Internal Resistance Tester; objective: test and grade used batteries by capacity and resistance for reuse in power banks and lights.
• Measured and analysed capacity in Ah for 10 cells and internal resistance in milli-ohms; 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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