DIY Power Bank Circuit and Tutorial – power bank building guide

Power banks provide emergency power supply to charge mobile phones, emergency lights or to use any device that supports USB power source.

It’s really convenient to have a power bank because it provides power back-up to charge or use your devices when you are travelling or far from home, and they can be expensive or inexpensive depending on the capacity.

Power bank capacity is measured using mAh, so a 10000 mAh power bank can hold more power than a 5000 mAh. Depending on the capacity, a power bank can be expensive, but with some basic knowledge in electronics, you can build one yourself quite easily, all parts are available online

So let’s jump to the power bank building tutorial

Parts you need to build a power bank at home yourself

To build a power bank, most importantly we need the following things:

1. 18650 Li-ion or Li-Po batteries
2. Control board
3. A power bank housing

You can get all these parts online.

18650 batteries

The heart of any power banks, the 18650 batteries are good choice for power banks, they have long life and provide good current.

They come with 3.7 Voltage and with different mAhs. It’s important to buy a standard 18650 battery from a reputed brand because there are loads of fake 18650 batteries being made boasting to have over 10000s of mAhs when in fact, most of them can provide only around 500 mAh or lower and die quickly.

You can add multiple batteries, the more batteries you add to your power bank,the more capacity it will have but keep in mind it will take longer to recharge with more batteries.

Control board

So the 18650 battery provide 3.7V, but a power bank must output 5V supply, so a control board is used in every power bank to step up this 3.7V to 5V supply.

The control board uses some ICs and inductor to boost the voltage and it also helps to recharge and protect the batteries from over charging and discharging

The board also includes the following things

• USB port
• Micro female usb port (to charge the power bank)
• LEDs to indicate battery levels

Some boards come with an LED for flashlight and a switch.

Building a Power Bank

So we learned about the things we need to create a power bank yourself, now let’s build one.

Building is simple, get some good quality wires, red and black. With a soldering iron, solder red and black wires on the control board. All the18650 batteries must be connected or soldered in parallel.

The black wire goes to BAT- or Battery- in the control board. The Red wire goes to BAT+ or Battery+, Next, the red wire goes to Positive (+) terminal of the 18650 batteries, black goes to the negative terminal of the batteries

Here is a diagram that will help you understand

Home Made Power Bank Diagram

Encasing the Power bank

You can buy enclosure, housing or cases online for your power banks. If you buy an enclosure, normally you will get the control board along with it. I recommend this, because if you only buy control board, it will be hard to get a matching enclosure

Choose an enclosure that will fit all your batteries, there are some power bank cases that can encase up to 8x or more 18650 batteries which can pack some power.