How To Make Power Bank at Home using 18650 Battery – DIY Project

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Are you tired of your phone running out of battery when you're out and about? Why not build your own DIY power bank at home using 18650 lithium-ion batteries? It's a fun and practical electronics project that not only saves money but also teaches you how battery systems work.

In this blog post, we'll guide you through creating your own power bank using easily available components. 


🧰 Components Required

To make this DIY power bank, you’ll need the following parts:



  • 🔋 3x 18650 Li-ion Batteries (same capacity recommended)

  • 🔌 TP4056 Charging Module with Battery Protection

  • 🔁 Boost Converter Module (3.7V to 5V)

  • 🧷 Battery Holder or Nickel Strips

  • 🔘 Mini Power Switch (optional)

  • 🧰 Wires, soldering tools, hot glue, casing/box

⚙️ Understanding the Circuit

The power bank consists of three core sections:

1. Battery Section

You’ll connect three 18650 cells in parallel to increase total capacity. Voltage remains 3.7V, but current capacity adds up. For example, 3 x 2000mAh = 6000mAh.

2. Charging Section

The TP4056 module handles charging through micro USB. It also provides protection against overcharge, over-discharge, and short circuits.

3. Boost Converter

This converts the 3.7V from the batteries to 5V output (USB standard) so you can charge your mobile or other gadgets.

🛠️ Step-by-Step Assembly Guide



🔹 Step 1: Prepare the Batteries

Use cells with the same voltage and capacity. Connect all positive terminals together, and all negative terminals together – this is called parallel configuration.

🔹 Step 2: Connect to TP4056

Attach the battery terminals to the TP4056 board:

  • B+ → Battery Positive

  • B– → Battery Negative

🔹 Step 3: Add the Boost Converter

Now connect the OUT+ and OUT– of the TP4056 to the input of the boost converter.
This will allow your battery to output 5V through the USB port.

🔹 Step 4: Add a Power Switch (Optional)

You can add a small switch between the battery and the boost converter to control power manually.

🔹 Step 5: Enclosure and Finishing

Place all components safely inside a plastic box or 3D-printed case. Use hot glue or tape to fix the modules in place.
Cut holes for USB output, micro USB input, and switch.



⚠️ Safety Tips

  • Never short the battery terminals.

  • Avoid soldering directly onto 18650 cells — use holders or spot welders.

  • Ensure proper airflow inside the casing to avoid overheating.

  • Charge only with the TP4056 module to prevent overcharging.

📏 Calculation Example

If each 18650 cell has 2200mAh, three in parallel will give you:
2200mAh x 3 = 6600mAh capacity at 3.7V.
After boosting to 5V, you’ll get approximately 4800–5000mAh usable capacity due to energy loss during conversion.

📦 Applications

  • Emergency phone charging

  • Portable light or fan power source

  • Educational DIY project

  • Travel-friendly backup power

🧠 Conclusion

Creating your own power bank is an excellent way to learn electronics while building something genuinely useful. With basic tools and inexpensive components, you can design a custom backup battery tailored to your needs.

So next time your phone battery runs low, you’ll be glad you built your own DIY power bank!

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