$3 DIY power bank with old phone batteries

Phones. They are almost always in our hands. Day in and day out. Powerful portable minicomputers which are controlled by our grubby fingers to give the outputs we desire. No wonder they are so prized! Now that phones are being taken practically everywhere, people also need a portable power source to charge their devices on the go. And those are power banks.These handy stores of electrons nowadays pack a powerful punch in a bite - sized package. Charging phones, receiving charge quickly and more. However, these lovely creations come with a price. First is the deprivation of Earth's resources due to mass production. Second is the pollution of the environment by incorrect recycling. Third is the price. The literal price. Most decent power banks cost north of $10 today! That is why I have constructed a guide on how to build a simple power bank with used phone batteries and a module for around $3 - 4. (Minus the price of the equipment)

To start this build, these are the parts and tools required :

Parts

5V 2.1A Power Bank Charger Module

3 batteries with at least a combined capacity of 5000 mAh and at most 7000 mAh and an individual voltage of 3.7 volts (Any brand; preferably lithium ion but those are common, so no problem. All of the battery specifications will be displayed on it to get the information.)
WARNING: I made a fatal error, where I used different - capacity batteries to create this device. This actually leads to a battery MELTDOWN, where different current flows actually kill the functionality of the batteries and is a dangerous thing to come by. Please take note of this and not use different capacity batteries in your own project.

Insulated wire (Can be harvested from other devices or bought. I harvested my wires, so I kept the costs down.)

Tools

Soldering iron or pencil

Solder wire

Glue gun (or any other glue)

Soldering flux

Solder remover

Vacuum pump (optional)

Scissors or a wire stripper

The method

1. Take the batteries. Switch on the soldering iron (or pencil) and apply a small blob of solder to each of the three batteries' negative and positive terminals. The polarities will usually be marked near the contact points of the batteries. Use soldering flux to ensure smooth, even blobs. If flux is unavailable, then try to do what is possible. It may be a bit frustrating.

2. Take the wire and cut it into 6 pieces of 4 - 5 cm long units. Strip the wires at both ends with a scissor or a wire cutter. Connect one wire to each terminal of the batteries by melting the solder already on the terminals and inserting the exposed copper part of the wire into the solder. Hold there until the solder has solidified.

The three batteries should look something like this when done :

4. Now, take the power bank module itself. Apply blobs of solder to the positive and negative terminals of the chip. The terminals will be marked by B+ and B-, indicating the polarity that has to go there.

Note that there is glue on some of the components. When I got my module, it was damaged and so I had to fix it via crude means. This doesn't mean that all modules bought are going to have defects, so don't worry. If there is a problem, fix it if possible or get a new, undamaged unit.

5. When the above is done, stack the batteries and just put the module in such a way that it can be known whether the wires connected to the batteries are long enough to reach the terminals on the chip. Don't glue them yet!

6. Now, take all the wires leading to the positive terminals to the batteries and solder all 3 of them to the positive contact on the chip. Now, do the same thing with the 3 negative wires and solder those to the negative contact on the chip. Use flux for a neat and secure finish.

                                           

                                                                                                                                                                     7. Glue 'em all together!

                                                                                                                                                                     And here is the finished product! It may look very impromptu, but looks can always be tweaked. The real point of making this device was to repurpose some phone batteries into a useful item. This may not be as good as mass - produced ones, but by reusing items like batteries and using less money, we are saving the environment from a lot more e - waste.
(Warning : This power bank may not work as effectively as store - bought ones, so please do this under your own discretion)