12V Lithium-Ion Battery Pack with Multi-Voltage Outputs
How to Build a 12V Lithium-Ion Battery Pack with Multi-Voltage Outputs | DIY Power Solution for Makers
Are you a DIY enthusiast looking for a compact and reliable power solution for your projects? Whether you’re into Arduino, RC cars, robotics, or portable gadgets, this custom-built 12V lithium-ion battery pack is a must-have. In this tutorial, I’ll guide you through the complete process — from components and features to step-by-step assembly and testing.
Why This Battery Pack Is Awesome
This isn’t just a basic battery pack. Here’s why it stands out:
Multi-Voltage Outputs: Get 3.7V, 7.4V, and 12V outputs from a single pack.- Built-In Voltmeter: Monitor battery status in real time.
- Modular Design: Easy-to-replace cells using 1S battery holders — no spot-welding needed.
- High-Quality PCB Integration: Clean, safe, and efficient power delivery.
- Perfect for Multiple Projects: RC, robotics, power banks, and more
Applications of This Battery Pack
This custom battery pack is super versatile and can be used in:
- Arduino and Raspberry Pi projects
- RC cars, drones, and boats
- Robotics and IoT devices
- Portable LED lighting setups
- Custom power banks
🛠 Components Required
- 3x 3.7v 2000maH 18650 Lithium Ion Cell
- 3x Single Cell 3.7v 18650 Battery Holder
- 3 Cell 40A BMS Board
- Mini Digital Voltmeter
- 2x 4 Pin Male JST Connector
- 4 Pin Male JST Connector
- 4x Crocodile Clips
- Universal PCB Mount Connector
- Screws & Spacers
- Prototype PCB Board
📟 Create Circuit Diagram
Before assembling any physical components, it’s essential to design a clear and accurate circuit diagram. This step helps you plan your connections, identify components, and avoid mistakes during the actual build.
⚙️ Development & Deployment Process
Building this multi-voltage lithium-ion battery pack involved several critical stages — from planning and prototyping to final assembly and testing. Below is a breakdown of the entire process.
🔹 Step 1: Add BMS Board and Solder
First we have to attach the 3S 40A BMS Board with the PCB then we will assamble rest of the components.
- Put the BMS Board to their desired mark on the back of the PCB
- Now solder the BMS with the board
- If you are unable to solder the BMS board directly to the PCB then you can use jumper wires to connect it.
🔹 Step 2: Add All Components and Solder
What to Add:
The mini digital voltmeter
An ON/OFF toggle switch
Output terminals (JST or banana connectors)
Connection wires to 3.7V, 7.4V, and 12V points from the battery
Solder wires from the BMS output (P+ and P-) to your power output
Why This Step Matters:
It ties everything together — the voltmeter, switch, and outputs — and ensures your battery pack is modular and functional.
🔹 Step 3: Add Spacers and Mount the Second PCB (Back Plate)
Why:
Adding a second PCB or a protective layer ensures the internal wiring and components are shielded from damage or shorting.
How to Do It:
Use plastic PCB spacers or standoffs to elevate the second board.
Secure it with screws or glue depending on your enclosure type.
This layer can also hold the voltmeter display or switch if you want it externally visible.
🔹 Step 4: Create the Output Connector Setup
What to Use:
A JST 4-pin female connector
Banana plugs or other output types based on your needs
Instructions:
Solder wires from the 3.7V, 7.4V, and 12V points to the appropriate pins of the 4-pin connector.
Add banana connectors or bullet plugs to make connecting to external loads easy.
Tip:
Label the voltages on the connector or color-code them for safety.
🔹 Step 5: Insert Batteries and Test Voltages
Caution:
Make sure all connections are correct before inserting batteries.
Steps:
Insert the 3 x 18650 cells into the holders.
Use a multimeter to measure voltages from:
Cell 1 (3.7V)
Cell 1 + Cell 2 (7.4V)
Full pack (12.6V fully charged)
Verify that the voltmeter display is working and showing the correct value.
🔹 Step 6: Test the Battery Pack with Real Loads
Try Powering:
LED strips
Motors
Microcontrollers like Arduino, ESP32, Raspberry Pi
Portable fans, mini amplifiers, or other 12V-compatible gadgets
This is the real-world proof that your battery pack works as intended.
🧪 Final Testing & Safety Tips
Make sure there is no heat buildup during operation.
Secure all components using hot glue or insulation tape for durability.
Always balance-charge lithium-ion cells using a proper charger.
Add fuse protection or a BMS (Battery Management System) for extra safety in production versions.
🔹 Bonus Step: Charge the Pack Using Any 12V Source
Yes, you can charge this pack using a 12V DC adapter or another 12V battery, as long as:
You charge through the BMS-protected charging port (P+ and P-)
The 12V source provides constant voltage, preferably via a 12.6V CC/CV lithium charger
DO NOT:
Charge directly through the battery terminals
Use unregulated or unsafe power sources
Safe Charging Options:
12.6V lithium battery charger
Solar panel with charge controller
12V lead-acid battery (with a regulator in between)
🧠 Applications of This Battery Pack
This custom battery pack is super versatile and can be used in:
Arduino and Raspberry Pi projects
RC cars, drones, and boats
Robotics and IoT devices
Portable LED lighting setups
Custom power banks
📝 Conclusion
Building your own lithium-ion battery pack is not only fun but also incredibly useful. With multiple output voltages, modular battery replacement, and a built-in voltmeter, this pack offers flexibility and functionality for makers of all levels.
Have any questions or want to showcase your version? Leave a comment or tag me on social media — I’d love to see your builds!
Watch the Full Video Tutorial
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