Project Hub /Automotive EV & Transportation/EV Battery Management System (BMS)/How to use a 4s 40A BMS Module to build Battery Packs?

Beginner

ANALOG / DISCRETE

Project Specific

3 – 6 Hours

Partial Kit

How to use a 4s 40A BMS Module to build Battery Packs?

Learn how to build a 4S Li-ion battery pack using a 4S 40A Battery Management System (BMS) module and test its safety features like overcharge, undervoltage, and short-circuit protection.

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.

1200mAh 18650 Li-ion Bat – Reliable 3.7V Power Cell Rs. 129.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
2-Slot 18650 Holder with Protective Cover and On/Off Switch – Case Rs. 109.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
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

We don't carry yet: Battery (generic / unspecified)
Battery Charger Module TP4056
DC Barrel Jack / Power Connector
Nickel strip
Voltmeter

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How It Works

This project centers around configuring a custom multi-cell energy storage unit using four individual lithium-ion cells tied together in a series arrangement (4S) to increase overall output voltage. To ensure safe and balanced operation, the cells are mechanically aligned using cell connecting brackets and permanently joined using nickel strips spot-welded across the terminals. A 4S 40A Battery Management System (BMS) module is wired directly to the pack, connecting to both the main power terminals and the intermediate node taps between each cell. The BMS actively monitors individual cell voltages and total current flow, protecting the chemistry from hazardous states such as overcharging, severe undervoltage, and accidental high-current short circuits. A DC female barrel jack and a manual switch are integrated to manage power delivery to an external load, represented here by a test bulb. Throughout the assembly and testing process, a digital multimeter and a standalone voltmeter are used to verify cell balancing, open-circuit voltage levels, and proper functional output before connecting any load.

Why Build This

Design and fabricate custom high-capacity battery configurations for electric vehicle prototypes and solar energy storage systems.

Apply fundamental principles of series cell balancing, power distribution, and active battery protection circuits in undergraduate engineering projects.

Gain practical competency in evaluating lithium-ion safety thresholds, thermal management considerations, and current-limiting behaviors under load.

Real-World Application

Custom battery packs for electric vehicles, solar power storage, portable power banks, and DIY electronics requiring safe multi-cell lithium configurations.

Skills You'll Learn

Lithium-ion pack spot-welding

Battery management system (BMS) wiring

Series cell voltage balancing

Multimeter diagnostics

DC power path integration

Short-circuit protection verification

Safety Precautions

Exercise extreme caution when working with lithium-ion cells and high current paths to avoid short circuits, thermal runaway, and potential fire hazards.

Technology Tags

BMS

BATTERY MANAGEMENT SYSTEM

LI-ION

CELL BALANCING

OVERCHARGE PROTECTION

SHORT CIRCUIT PROTECTION

LITHIUM BATTERY PACK

Frequently Asked Questions

Why is it important to use cell connecting brackets instead of taping the batteries together?

Cell connecting brackets maintain secure physical spacing and structural rigidity, preventing vibration-induced shifting that could stress or tear the spot-welded nickel strips.

What is the purpose of connecting the intermediate voltage taps to the BMS module?

The intermediate taps allow the BMS to monitor the individual voltage of each of the four cells in the series string, ensuring that no single cell gets overcharged or over-discharged relative to the others.

How should I verify that the battery pack is safe before connecting the test bulb?

Use a multimeter to measure the total output voltage across the main terminals and check each individual series stage to confirm the cells are balanced and within safe operating voltage limits.

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.

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