In this instructables I will show you how you can make your own power bank using easily available and inexpensive components. This backup battery contain 18650 li-ion battery from old laptop or you can buy new ones. Later I made a wooden casing with cool looking Plexiglas lights to have a cooler aesthetic feel. I will walk you through each and every steps in building this.
Watch the video for easy understanding
The specifications are:
Capacity: 6600mAh (Expandable)
Output voltage: 5V
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Step 1: Materials Required
18650 li-ion battery
TP 4056 battery protection module
6009 Boost Converter module
330 ohm resistor
USB female socket
Plywood ( 3/4" and 1/4" thickness)
Some basic woodworking tools like Drill, hacksaw, Chisel,etc
Step 2: Making the Battery Pack
The terminals of 18650 batteries are cleaned using IPA solution.
Apply a little bit of flux and using the Soldering iron tin the surface of battery terminal.
Also strip the insulation of the wire at the ends and tin them . The Batteries has to be connected in Parallel configuration. Solder the wires to the battery and do not over heat the battery while soldering.
My batteries were original Samsung ICR18650-22 model and I suggest you to use the good quality batteries for extended life and safety.
I am using 3 battery in parallel to get a total Capacity of 6600 mAh. You might want to add more batteries in parallel to increase the capacity.
Later tie the batteries using Electrical tape or kapton tape.
Note: It is important to charge the batteries to same voltage level before connecting in parallel. Else the battery with higher potential will discharge to lower potential battery and huge current flows through them which results in excessive heat.
Step 3: Battery Protection Circuit
The terminals of battery protection module TP4056 is indicated with the symbols.
Battery has to be connected to the B+ and B- terminals.
The output is connected to Out+ and Out- terminals. Any mobile phone charger with USB mini can be used to charge the battery.
TP4056 module protects the battery from over charge, over discharge and short circuit. The lithium batteries has to be handled carefully. The voltage level has to be in the range of 2.7V to 4.2V*. 2.7 V indicating 0% state of charge and 4.2 V 100% state of charge.
The LEDs on the board indicates the charge status of the batteries.
RED LED - Charging
GREEN LED - Charging Complete.
* the range mentioned is for lithium ion battery and may vary for other types of lithium batteries.
Step 4: Boost Converter Circuit
Refer the image for circuit connections or watch the video for easy understanding.
Connect the output of TP4056 module to IN + and IN- of boost converter module.
Add a Switch before the IN - terminal in series.
The work of the 6009 boost converter module is to step up the voltage of battery(3.7 v nominal) to stable 5 V.
The potentiometer (trimmer ) on the boost converter is varied to set the output voltage to 5V . Place the multi-meter probes on the output to measure the voltage. Make sure the output voltage is 5V before connecting the mobile phone.
Note: The output of the Boost Converter should never exceed 5V.
Step 5: USB Output Connection
Output of boost converter is connected to the USB female jack . The image shows the pin configuration of USB socket.
I soldered the USB onto a piece of pref-board and connected the wires coming from the boost converter. I also connected two Blue LEDS in parallel to the Output and it turns ON whenever the power bank is active. The circuit diagram is in the pictures attached above.
I de-soldered the on-board charge indicator SMD LEDs on TP4056 module and soldered some extension wires and soldered RED and GREEN 5mm LEDs which will be mounted on the case.
Before proceeding to next step I tested if the circuit is working properly by connecting the circuit to my phone via USB Cable and it does Work!
Step 6: Making the Wooden Casing
I gathered all the required dimension of wood. The idea is to bore a square hole on a piece of 3/4" ply wood with 1 cm wall on all the sides. All the components is fixed inside that.
Then a thin sheet of plywood is covered on both the sides to make it as a box.
The holes to mount the led and USB connection is done on the 3/4" plywood. As a part of aesthetic feel I wanted to add the acrylic sheet on the perimeter of box and led lights it up whenever the switch is on. So I decided to cut 4 pieces of 1 cm each and glued it on the wood.
If you are interested my box dimension was 11cm*9.5cm. This may vary according to your design and number of batteries.
Later I sanded the wood using 100 grit sand paper and applied 2 coats of wood polish using a rag to give nice surface finish.
Step 7: Assembly
I tested if the circuit is working and glued all the components in the wooden case using hot glue.
Then I use some wood glue to attach the other plywood piece to complete the assembly and clamped it until the glue was dry. You can refer the images on how I assembled the circuit.
I have been using this power bank for 2 weeks now and I am getting good use of it I am able to charge my phone once. I think this could be improved if new batteries are used.
I also suggest to use the ready-made power bank kits if you want to save yourself from Soldering and the comes with the case similar to commercial ones. But I wanted this kind of custom made power bank that not only works really well but also looks cool!
Please leave a comment if you come across any doubts or you have any suggestions.
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