Step 1: Thing You Will Need:
- 1 female USB port.
- 1 male USB port.
- when plastic box as shown in the picture.
- 2 x 3.7V parallel connected 18650 batteries from an old laptop.
- two camera batteries of 1.2V each.
Step 2: Spot Welding:
Glue 1.2 volts small batteries together so that they can be connected in parallel to each other.Now each 1.2 volt battery is rated 2400mah.Now take a Nickel strip and spot weld their positives together and then there negative together.
Now you will have it as a 1.2v 4800mah battery since they are connected in parallel.
------> Spot welding video
The parallel connected batteries from the laptop should already be spot welded.Now glue both the sets together such that the negative side of 1.2 volt battery should be next to the positive side of the laptop battery.Now series connect the two batteries by doing spot welding for the final time as shown in the last picture of this step.
Step 3: Connections:
Take off the end cover of the male female USB ports.You will find four wires in it.The Black And The Red wires are only of use.Cut off the rest of them.The red wire is the positive one and the black wire is the negative.Connect the two ports in parallel as shown in the picture and increase their lengths by joining additional wires.
Make rectangular holes in the box with a razor such that the USB ports fit in them perfectly.Place the USB ports in the holes and hot glue them with a silicone gun.Now glue the batteries in the box.
Since the batteries were connected in series, they will together make up a voltage of 4.9 volts.The voltage range for charging mobile phone is 4.5 volts to 5.1 volts.
Now join the negative terminal of the battery to the negative (black) terminal of the USB ports and positive terminal of the battery to the positive(red) terminal of the USB ports.Don't forget to insulate the wires with a tape.
Step 4: Test It:
you are done!
Connect your mobile phone to the power bank with a data cable.It should start charging.
Now, to charge power bank itself, you will need a male - female cable.Connect the female side of the cable to the male port on the power bank and connect the male side of the cable to the charger.It will start charging.
Charge it for 1 to 2 hrs and then use it.
Watch full video