Repurposing Vape Cells for UAV Power Packs

Disclaimer

Just as a preface, this project is highly experimental and I am very much a beginner in electrical engineering and battery building. Now although the design, I think, is very good - it is probably not all that safe. As we are using so many cells in parallel which is (safer than series) the high cell count means more room for failures, and with used cells - this risk is higher. So just be careful and don't take what I say here as gospel, research, very carefully, your project specifics before building your own version.

Overview

Vaping! It really grinds my gears that most vapes are consider single use yet use fully rechargeable lithium cells, that are thrown away like cigarette butts. What a ridiculous idea. Finally, some governments are beginning to building policy to stop this sort of vape and even ban them but it will take some time. The only benefit of this situation is that us hackers suddenly have a significant supply of low capacity barely used lithium cells, found in the streets, bathrooms, bins and bars. If you go into these places they often have a bin full of them which they will happily let you take, same goes for vape shops. So let's give these batteries a new life!

The aim is to build a 14.8 V DIY Li-ion Battery Pack, to do this we repurpose 104 salvaged 13350 Li-ion cells (3.7 V, 500 mAh each) into a high-capacity battery pack. The cells will be arranged in a 4S26P configuration to achieve a 14.8 V nominal output with a total capacity of 13 Ah (~192 Wh).The pack uses a 4S BMS with cell balancing for safe charging, discharging, and cell health. I wanted to create a safe, cost-effective, and reusable power source using recovered vape cells, suitable for 12–15 V applications involving UAVs, portable power packs, IoT projects, and maybe even light-duty energy storage. In this guide, I'll go over sourcing batteries, organising them, then the design and electrical plans.

Battery Harvesting

Be sure to check the condition of all the batteries, not just cosmetically but also by measuring voltages and checking capacity. Anything below 3v is not great, but still maybe usable. Anything 2.5v and under, don't bother not worth it. Remember these cells are considered single use and have very little or no under voltage protection so people will just keep puffing on them until they are totally dead, so with most discarded vapes you can expect they will be quite over discharged. But most can be saved with a slow charge.

You may actually get the odd rechargeable cell in there with some usb charge circuitry, keep these they can be useful for other smaller battery packs. Check them thoroughly though.

Taking apart the vases you will mostly fins very few components: a sponge filter, a stinky juice reservoir, a hearing element, control board and a flow sensor. Normally shoved in an aluminium tube with some end caps. See images.

You should end up with a list of scavenged parts like this:

- 105 x 500 mAh- 22 x 360 mAh- 2 x 350 mAh- 3 x 400 mAh- 1 x 550 mAh- 1 x 1000 mAh- 1 x 1400 mAh- 1 x 600 mAh- 2 x 360 mAh capacitor- 2 x type-c charge board

Interestingly they are using capacitors in some of these which I did not expect.

For this build I will use the largest quantity in the list (105 X 500ma cell) as our chosen cell, do not mix cell capacities when building batteries as they will not balance properly.

Battery Design and Assembly

I wanted this system to be modular and swappable. So that cells could be replaced without needing extensive resoldering or rebuilding. This means making each cell independently removable and not using solder pads. I did this using a sandwiching design where we have a honeycomb like spacer for all the cells and end caps with nickel strips to connect the lathe parallel connections and then walls separating the 4 series groups. This design is cool but perhaps a little impractical as having no direct soldering leaves some risk of batteries lossing contact. I tried to mitigate this by weaving cable ties through the assemble and tightening them down snug. See images below.

I used a basic 4S BMS board found here, it's 4S 16.8V 40A so should be plenty suitable for our application.

Drone Use Case

My specific application will see this pack used as a modular drone battery pack. This means I have made certain decisions during dealing to make it suitable for my experimental drone platform, these choices include ensuring 14.8v nominal voltage, originally a high discharge rate would be important for drone flight but this is quite unachievable with used vape cells as they are cheap low quality slow discharge cells - not a good choice for drone batteries as they are designed to dump so much current to power the drone motors, normally around 80A.

This leaves our pack not currently usable for powering the motors but still useful for lower discharge, payload powering such as companion computers, sensors and communications.

This new battery should also make the drone more stable as the battery will be well distributed within the drone's centre of gravity. The will mean less swaying and better control in the air.