How to Find Free LiPo Batteries From the Street and Use Them in Projects

With the unfortunate rise in the use of vape devices, more and more of them can be found thrown out in the street.

This is not just a littering issue but also a resource use issue as everything inside them can be reused/refilled but still, they are made and sold as single-use items. Worst of all, they use rechargeable lithium polymer batteries that are just thrown out in the garbage after their first use 🤯🤯🤯

I'm sure that someone out there is recycling these but if you are a maker with a need for batteries for your projects you can basically get them for free if you find devices like these that are thrown.

There is one caveat though for charging them but I'll show you how to create a charger for them so keep reading!

TP4056 protection module - https://s.click.aliexpress.com/e/_DBnW74x

Soldering station - https://s.click.aliexpress.com/e/_DmXnqLd

Assorted resistors - https://s.click.aliexpress.com/e/_Dkk1dQn

SMD Resistors - https://s.click.aliexpress.com/e/_DBprhBh

Pliers - https://s.click.aliexpress.com/e/_DeCBP8j

Tweezers - https://s.click.aliexpress.com/e/_DDgKQJV

Wire snips - https://s.click.aliexpress.com/e/_DCflWiT

The two devices that I took apart were given to me by some friends that use them. Once they are "empty", there is no way for them to reuse them so they were previously throwing them in the garbage.

I ask them to keep them for me so now I have already accumulated a few of them.

Additionally, it is not uncommon to find them thrown out in the street, on the curbside, or next to sidewalks. Since you don't know who their user was, it is necessary to disinfect these devices before opening them up by just wiping them with alcohol.

In any way, you should wear gloves while handling these devices as they can still hold some liquid inside.

To open up the devices, you will need just a pair of pliers so you can twist off the end caps. These come off easily but in some devices, they might be glued on so a bit of force is required.

Once the end caps are out, the inner contents can just be pushed out by using the dull end of a bamboo skewer. It is important that you don't use anything conductive to push as you might cause a short circuit and you can damage the battery in the process.

When the cartridge, the battery, and the sensor are out, you are left with a metal/plastic tube that you can also choose to keep for a project or you can throw for recycling.

To release the batteries, you will need a wire cutter to gently cut the wires next to the battery tabs and again, make sure that you are only cutting one wire at a time in order to prevent shorting out the battery.

Once the battery is released, you can use some paper towels to wipe them clean from any excess liquid that might be on them and you can now get rid of the gloves as well.

The devices have holes on both sides and on the bottom side, there is a little pressure sensor.

Once suction is applied from the top, the sensor turns on the heater and the heater then vaporizes the liquid inside. The heater is made out of some resistive wire that is then winded as a coil and wrapped around with a wick or some cloth material for better contact with the liquid.

Some pressure sensors also have a small led on them to indicate operation or empty battery, depending on the model.

In order for us to know if the batteries are safe to be used and are not emptied too much, we need to measure their voltage across the terminals.

In general, the batteries should not be lower than 3V but most of them will still be OK even if discharged down to 2.5V.

If there is a device that uses this kind of battery, the battery can be replaced immediately but if you want to use the battery in your custom projects, then we will need to create and add a protection circuit to it so it can be protected from over-discharge and over-voltage.

A typical module used for the protection and charging of lithium cells is the TP4056 module which can be purchased online very cheaply. The original intent of the module is to charge 18650 batteries and since they are of a much larger capacity, the charging current on the device is usually set as 1A.

In our case with these smaller batteries, the typical charging rate is 0.5C or lower, which for a 400mAh battery equals a charging current of around 200mA.

So we need to lower the charging current of the TP4056 module by replacing the programming resistor on the module which is marked as R3 in most of the boards that I've seen. Depending on your version, this might be different so please double-check that.

Some of the modules use different sizes of SMD resistors so this might be tricky but the micro USB version has a manageable 0805 size resistor.

Once the original 1.2K Ohm resistor is removed, I replaced it with a 5.6k Ohm resistor so I can get a charging current of around 200mA. The resistor is first soldered with one of the legs on the pad, sticking out of the board, and then once the second leg is also soldered, you can twist it so it lays within the board footprint and does not stick out.

With the module ready, you can solder it to the battery, or if you want you can also wire the meter in series to check on the charging current.

When attaching the module to the battery it is critical that you match the polarity of the battery with the marked polarity on the board as otherwise, you can destroy the module and the battery. The receiving pads for the battery are marked as B+ and B- on the module so you need to match them with the battery's positive and negative terminals.

With the module attached, any output from the battery should now be attached to the OUT+ and OUT- pads on the module and not on the battery directly. This way we can be sure that the module will monitor the voltage of the battery and that once the battery is discharged, the output will be cut off in order to protect it.

Now that you have a protected battery you can safely use it in projects. The battery might be small but if you connect a white LED with a 70 Ohm resistor on its output, the LED will be lit for close to 40 hours.

An Arduino Pro Mini, depending on the sensors and the sketch on it can run in excess of 250 hours without using sleep mode so a sensor that is powered from this battery and uses power saving can easily operate for several months on this battery without needing to be recharged.

As you can see, this opens up a lot of possibilities so if you would like to see some projects where I use this type of battery in a project, then make sure that you follow me here on Instructables and also subscribe to my YouTube channel.

Thank you for reading!