Table of Contents
Introduction
Are you tired of struggling with unreliable power sources for your robotics or DIY projects? Look no further! In this comprehensive guide, you will build a 12V power supply using 18650 lithium iron batteries, a BMS 3S 10A charger, and a custom 3D-printed case. This power supply works efficiently and provides versatility, making it ideal for robots, Arduino boards, motor drivers, and more. By the end of this blog, you will understand how to assemble, connect, and optimize your very own 12V power supply system.
Why a 12V Power Supply is Essential for Your Projects
A 12V power supply plays a crucial role in electronics and robotics. It powers motor drivers, Arduino boards, and LED indicators, ensuring smooth operations. Lithium iron batteries, like the 18650, provide high energy density and long lifespan. Pairing them with a BMS 3S 10A charger enhances safety and efficiency, making your 12V power supply both powerful and dependable.
Materials You Need
Before starting, gather these essential components:
- 18650 Lithium Iron Batteries (3 cells) – These batteries form the core of your 12V power supply.
- BMS 3S 10A Battery Charger Protection Module – This module ensures safe charging and discharging.
- 3D-Printed Case – A custom enclosure to protect your battery pack.
- JST 2-Pin Connectors (Male and Female) – These connectors simplify connections to motors or other devices.
- Male and Female Power Jack – The female jack is for charging the battery, while the male jack powers the Arduino.
- 3-Pin Toggle Switch – It controls power flow efficiently.
- 3mm LED and 1k Resistor – These components act as a power indicator.
- Wires and Soldering Tools – These tools ensure strong electrical connections.
Circuit Diagram

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Step-by-Step Guide to Building Your 12V Power Supply
Step 1: Prepare the 18650 Battery Pack
Arrange three 18650 lithium iron batteries in a series connection. Connect the positive terminal of the first battery to the negative terminal of the second battery. Then, link the positive terminal of the second battery to the negative terminal of the third battery. This arrangement delivers an output of approximately 12V power supply.
Step 2: Connect the BMS 3S 10A Module
The BMS (Battery Management System) protects your batteries. Wire it as follows:
- B1 connects to the positive terminal of the first battery.
- B2 connects to the connection between the first and second batteries.
- B+ links to the positive terminal of the third battery.
- B- attaches to the negative terminal of the first battery.
This setup ensures balanced charging and discharging, prolonging your battery pack’s lifespan.
Step 3: Wire the Output Connections
Now, wire the BMS output terminals to the power jacks and JST connectors. The positive BMS terminal connects to the positive wire of the female power jack and the first pin of the toggle switch. The negative terminal links to the negative wire of the female power jack, the JST connector, and the LED’s negative terminal.
Step 4: Add the Power Indicator LED
To signal when your 12V power supply operates, wire a 3mm LED in series with a 1k resistor. Connect the resistor to the LED’s positive terminal and attach it to the first pin of the toggle switch. The LED’s negative terminal connects to the BMS negative output.
Step 5: Install the Toggle Switch
The toggle switch functions as the main control for your 12V power supply. Connect its middle pin to the BMS positive output. The first pin links to the LED, female power jack, and JST connector. Leave the third pin unconnected.
Step 6: Connect the Male Power Jack to the Arduino
The male power jack supplies power to the Arduino. Simply plug it into the Arduino’s DC input. This step ensures a stable 12V power supply to your microcontroller.
Step 7: Assemble the 3D-Printed Case
After securing all connections, place the battery pack, BMS, and wiring inside your 3D-printed case. Ensure proper placement of the toggle switch, LED, and power jacks for accessibility.
Note: This 3D model is for personal use only. Commercial use, distribution, or modification for profit is strictly prohibited.
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Testing Your 12V Power Supply
Before using your 12V power supply, test it using a multimeter. Check the voltage at the female power jack and JST connectors. Ensure the LED lights up when the toggle switch turns on. If everything functions correctly, your 12V power supply is ready for use.
Applications of Your 12V Power Supply
Your 12V power serves multiple purposes:
- Robotics – Powers motor drivers like the L298 for smooth movement.
- Arduino Projects – Provides stable power to microcontrollers and sensors.
- LED Lighting – Illuminates projects with bright, energy-efficient LEDs.
- Portable Devices – Enables outdoor electronics with reliable power.
Tips for Optimizing Your 12V Power Supply
- Use high-quality 18650 batteries for better performance.
- Regularly inspect connections to prevent power loss or short circuits.
- Monitor battery health using the BMS to track charging and discharging cycles.
- Upgrade your 3D-printed case to enhance durability.
Conclusion
Creating your own 12V supply expands your electronics and robotics capabilities. With a 3D-printed case, 18650 lithium iron batteries, and a BMS 3S 10A charger, you now have a stable power source. Whether for robots, Arduino, or LEDs, this 12V power supply fulfills your needs efficiently. So, grab your tools, follow this guide, and elevate your DIY projects!
Commonly Asked Questions
1. Can I use a different BMS module?
Yes, but ensure it supports a 12V power supply configuration.
2. How long do 18650 batteries last in a 12V power supply?
Battery life depends on usage and capacity, but typically lasts several hours.
3. Can I charge my 12V power supply while using it?
Yes, if your BMS supports simultaneous charging and discharging.
4. Why is my LED not turning on?
Check connections and ensure the resistor is correctly wired.
5. Can I use this 12V power supply for other devices?
Absolutely! It powers various electronics, including routers and surveillance cameras.
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