Hii friend,

We can require power bank any time.In reainy season most of the time light is not available.and phones gone to battery discharge then we can't do anything.so we can overcome from this situation by making a power bank.Using Power bank we can charge our phones and we can operate other electronic devices that are operated in DC 5V.

Power bank -

Power bank is an electronic device that store energy.and we can use that energy in other electronic devices.

So today I am going to make a power bank using old mobile phones batteries.This power bank will be very cheap and it can make at home.

Let's get started,

Step 1: Take All Parts Shown Below

Materials required -

(1.) Mobile batteries - 3.7V

(2.) Power bank kit

(3.) Connecting wires

(4.) USB data cable (for charging)

Step 2: Solder Both Batteries

Since we know that batteries have +ve and -ve terminals.

So first we have to solder Both batteries in parallel.

* Solder +ve wire of battery-1 to +ve wire of battery-2 and

-ve wire of battery-1 to -ve wire of battery-2 as you can see in the picture.

Why we solder in parallel -

When we connect batteries in parallel then its output current is increases but voltage will be same.To increase the output amount of current we solder batteries in parallel.

Step 3: Connect Batteries to the Power Bank Kit

Next connect the output wires of batteries to the kit.

In power bank kit polarity is already indicated.So connect +ve wire of battery to +ve of power bank and solder -ve wire of battery to -ve of power bank kit as you can see in the picture.

Why we solder this kit -

This kit will boost the voltage.It will boost from 3.7V to 5V.That's why we need to use this kit.

Step 4: Check Battery Charged Percentage

Now our power bank is ready, so first check how much power bank is charged by pressing push button of power bank kit.LEDs of power bank kit will show its percentage.

If it is not charged then do charge and use this power bank.