Introduction: Power Bank From Left Over Parts
Hi, this instructable is on building a power bank from left over parts. I started this to use up some left over parts and pass the time. It's made from six 18650s, an old wireless qi charger, TP4056 Li-ion charger and a couple 3.7V to 5VDC USB boosts.
Disclaimer: I'm not responsible if anyone injures themselves after building a project identical or similar to this instructable.
Step 1: Parts and Equipment
All the equipment and electronics used here are things most DIYers will have. Below is a list of equipment and parts used:
- Screw drivers (I'm using a posidrive)
- Wire cutters
- Wire strippers
- Digital vernier calipers (used for measuring the modules when designing the case)
- Soldering iron
- Glue gun (or any type of adhesive you use) I recommend glue guns or loctite super glue.
- 6 x 18650 Li-ion batteries, I had some cheap ones from banggood left over.
- 12 x 18650 End holders
- 2 x 3.7V -> 5V USB boosts
- 1 x 3.7V -> Adjustable boost (I set it to around 10VDC)
- 1 x 7805 (Voltage regulator)
- 1 x 100uf 16v Electrolytic capacitor
- 2 x 104 Ceramic capacitor
- Red and Black wire (you can use any, just easier when colour coded)
- 2 Or 3 pieces of nickel strips (used for connecting the 18650s together)
- TP4056 Li-ion charger
Step 2: Circuit Design
The images above show some of the electronics I used within this project. There are two usb boost which work at 500ma, a TP4056 1A li-ion charger, 7805 for 5VDC a wireless charger and then a couple little electronic components.
The diagram image shows how the circuit is wired up. (sorry for the hand drawing, if anyone knows of some good software please comment below).
Step 3: Create the Battery Pack
The battery pack is made up of 6 18650 li-ions. These were bought from banggood for around $7 for a pack of 4. supposedly they are meant to be 4000mah however I have tested they are more around 2300mah. This is very common while buying these sort of batteries. Please be careful when buying batteries. Don't be fooled!
Apart from this, they work perfectly fine. To start making the battery pack; put the holders onto the ends of the batteries, these holders clip into each other to create one huge pack. Once this is complete use either a soldering iron or spot welder to attach the nickel strips to the battery ends, this is to create a pack of 1S6P (1 series and 6 parallel).
Step 4: Print the Case
The case needs to hold all the electronics hence this needs to be very accurate with the dimensions. Start by laying out the electronics how you will have them within the case. The image above shows this, although for image reasons the wireless charger is on top of the batteries when in real life it's below. I measured where the electronics will interact with the case (e.g. the female USB A) and where I will be glueing them. I designed stand offs for where the electronic modules are glued.
Attached are the STL and DWG files for the case and top. I printed these on my delta (220 diameter) printer.
Step 5: Create the Circuit
This step is all about wiring the modules together and making the ciruit which regulates the voltage to 5v for the wireless charger. The images above shows me making the circuit and wiring up the modules. These have been made from the diagrams in the step earlier.
A couple notes here: I need to add a heatsink to the voltage regulator since currently it is heating up quite a bit. I'm going to look into getting a 3.7v to 5v set module for a future improvement however like I said before, this is made from old parts.
Step 6: Glue Parts in Place Within the Case
This is quite an obvious step; to hold all the parts and modules in place they need to be glued. I chose to use a glue gun for this however super glue would also work. Using the block stand offs within the case I was able to glue all the modules in place. The images attached show how this looks when glued.
Step 7: Test
Two of these pictures above were taken before assembly hence them being the pre-final test. This was to ensure the TP4056 and USB boost worked as expected which they did. After this simple test, I tested the ability to charge the unit using the TP4056 module. In the past I have had issues with some of these modules so a friendly tip is to always check they work before implementing them in your project (good tip for all modules actually :) ). The final test is to ensure the wireless charger is working through the casing.
Step 8: Screw Top Onto the Case
This last step is to screw the top onto the case, once this is complete the power bank is ready to use. I'm using M4 x 40mm bolts and M4 nuts. I had to print the top cover on it's side hence the spine to stop it for falling over during printing. This can be cut off quite easily since it's only 1mm thick.
Once screwed on this is ready to use.