Project Hub /Test & Measurement Instrumentation/Component & Cable Testers/18650 Lithium Battery Capacity Tester using Arduino

Intermediate

ARDUINO

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

18650 Lithium Battery Capacity Tester using Arduino

Build an Arduino-powered battery capacity tester to accurately measure the charge capacity of 18650 lithium-ion cells and identify counterfeit or degraded batteries.

Originally published on CircuitDigest

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

Arduino Nano C Type V3 ATMEGA328 with Soldered Headers Rs. 608.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
DC Motor Plastic Fan Blade Rs. 19.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: LCD (generic / unspecified)
Voltage Regulator IC (7805 / LM317 / 1117)
Potentiometer / Trimpot
Capacitors
DC Barrel Jack / Power Connector
Thyristor / SCR / Triac / Varistor / Fuse
Transistors (BC547 / 2N2222 / TIP / MOSFET)
Perfboard / Veroboard / Stripboard

Browse all components

How It Works

The 18650 Lithium Battery Capacity Tester is an embedded system designed to measure the total charge capacity of a lithium-ion cell by discharging it through a controlled load. At the heart of the circuit is an Arduino Nano, which monitors the battery voltage and calculates capacity over time based on the discharge current. Power is supplied to the control circuitry via a 12V power supply regulated down to 5V using a 7805 positive voltage regulator IC, ensuring stable operation for the microcontroller and the 16x2 character LCD. The LCD provides real-time readouts of the testing parameters and calculated results. To discharge the battery in a controlled manner, the circuit utilizes an IRF540N N-Channel MOSFET acting as an electronic load, paired with a heavy-duty 2.2Ω 5-watt power resistor. An LM741 operational amplifier IC is integrated into the control loop to help stabilize and regulate the current passing through the MOSFET, with a 10kΩ trimmer potentiometer allowing for manual adjustment or calibration of the circuit parameters. Additional passive components, including a 33kΩ resistor and a 0.47uF capacitor, are used for biasing and stability within the analog stages. Users assemble this circuit on perfboard using a soldering kit, connecting the battery securely via PCB screw terminals and interfacing with the system through a DC power barrel jack connector. Throughout the test cycle, the Arduino continuously samples the battery voltage, tracks the duration, and stops the test once the cell reaches a safe lower voltage threshold, preventing over-discharge.

Why Build This

Accurately test, grade, and sort reclaimed or newly purchased 18650 lithium-ion cells for DIY power banks and portable electronic projects.

Evaluate battery health and identify degraded or counterfeit cells before integrating them into high-capacity energy storage systems.

Gain practical undergraduate-level experience combining analog operational amplifier feedback loops with microcontroller-based digital data logging.

Real-World Application

Used by hobbyists and engineers to test, sort, and grade reclaimed or newly purchased lithium-ion batteries for DIY power banks, solar energy storage, and portable electronic devices.

Skills You'll Learn

Analog voltage regulation

operational amplifier feedback configuration

MOSFET current control

analog-to-digital conversion

timing and data logging with microcontrollers

character LCD interfacing

perfboard circuit assembly and soldering

Safety Precautions

Lithium-ion batteries can pose fire and explosion hazards if short-circuited or over-discharged. Ensure proper voltage thresholds are used and monitor the temperature of load resistors and heat sinks during operation.

Technology Tags

ARDUINO

BATTERY TESTING

MOSFET

OPAMP

LCD DISPLAY

PWM

POWER MANAGEMENT

Frequently Asked Questions

Why is a heavy-duty 5W resistor used instead of a standard small resistor?

Discharging an 18650 battery draws significant current, which generates substantial thermal energy. A standard small resistor would overheat and burn out quickly, whereas a 5-watt power resistor is rated to handle higher continuous thermal dissipation safely.

What is the role of the LM741 operational amplifier in this circuit?

The LM741 op-amp is utilized within the analog control circuit to help regulate and stabilize the gate drive for the IRF540N MOSFET, ensuring a precise and steady discharge current flows through the load resistor.

Can I use this tester with other battery chemistries besides lithium-ion?

This project is specifically designed around the voltage thresholds and discharge characteristics of 18650 lithium-ion cells. Using it with other chemistries requires modifying the firmware voltage limits to prevent over-discharging or hazardous operating conditions.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

PRJ-00578