Homemade Power Bank

Next Task: Waiting on paper design

Introduction and Project Planning

For this simple project, I want to create a USB power bank, utilising some 18650 Li-ion batteries I have lying around from previous, smaller power banks. I want to combine these batteries to create a larger, high capacity power bank that I can take to college and work. I want the power bank to be able to charge my phone fully and have a compact design for portability. This project shouldn’t take much to develop and I already have the components on hand to create the power bank.

Analysis and Specification

  • 18650 Battery Powered
  • Can charge phone from 0% to 100%
  • Compact design
  • Easy to use

Project Design and Project Development


  • 3x 1800maH 18650 Li-ion battery
  • 1x Lithium charging and 5V boost module (Salvaged from old power bank)
  • 1x 3D printed Casing
  • Various wires and connectors for the build

The power bank will be charged via a USB cable, the module I have chosen to use is an all in one module with a charging circuit with overvoltage protection. Also, this module has the ability to output 5V boosted up from the 3.7V lithium batteries, this will be perfect for charging mobile phones and other 5V devices.

Circuit Schematic


The circuit schematic for this project is incredibly simple. I simply need to connect both lithium cells to my all in one lithium charging / boost module. This module will control the charging of the module, with protections etc, and the boosting of the battery voltage to 5V, so it can power phones and other 5V devices. I used a new software package to design this schematic, Fritzing. This software is open source and runs as a portable application, it’s fantastic. However, it didn’t have a schematic icon for my lithium charging module, so as a placeholder I used a generic USB icon and a generic module icon, which should represent the connection justs fine.

Casing Design

Implementation and Testing


18650 Battery: http://img.dxcdn.com/productimages/sku_408231_1.jpg