How do vape companies get away with putting perfectly good rechargeable lithium batteries in a single-use device? And why does it seem like there are so many more of these around all of a sudden? It’s ridiculous.

I think the shift has something to do with the Juul ban. Juul had a significant share of the market with its rechargeable, cartridge refillable device. When it was pulled from the U.S. market in 2022 by the FDA, new competitors popped up to fill the demand. In a market where brand recognition could mean a target on your back from regulators, companies aren’t incentivized to make a refillable system. And selling you a completely new device every time the old one wears out is more profitable than selling you just a cartridge. Unless lithium becomes much scarcer, or it becomes a legal requirement to make them infinitely refillable, I don’t see this trend changing anytime soon, unfortunately.

Some brands do include a charging circuit to make use of a larger liquid reservoir. But once the liquid runs out, the device is still intended to be thrown out.

How did I get this many devices to take apart? Besides picking them up off the sidewalk, I asked my local Buy Nothing group and found a few willing folks who knew better than to throw these in the trash and were happy to offload their hoard.

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Lithium Battery Overview

Lithium batteries are used in everyday devices like laptops, cell phones, hybrids, and electric cars. They are much lighter than traditional alkaline batteries and can last much longer. They can also be recharged multiple times — it’s no wonder that they’re in everything nowadays.

Lithium batteries contain layers of materials folded up together into a small shape. Energy is stored on either side of a battery “stack” and it wants to get from one side to the other, and circuits get power by making the charges do work along the way. As the battery discharges and produces an electric current, lithium ions are released by the anode to the cathode, causing a flow of electrons from one end to the other.

When charging, the opposite happens: the cathode releases lithium ions, which are then obtained by the anode. You can think of the act of charging like pushing the energy back to the other side so that it can be ready to go again. And if the layers are breached by, say, a puncture or by crushing, the battery can become shorted out, and the electrons get way too excited.

The C-rate is the measure of how quickly the battery can be discharged and recharged without damaging it. Failure modes include overcharging, over-discharging, and short-circuiting. Always use a charging rate appropriate for the battery’s C rating, or a conservative guess.

Lithium Battery Do’s and Don’ts

Here’s a list of do’s and don’ts when using LiPo batteries:


  • Charge your battery slowly and evenly, at a rate appropriate for its capacity
  • Store your battery in a cool place
  • Get a fireproof battery bag to keep your batteries in


  • Don’t charge or discharge your battery too quickly or let it get too hot
  • Don’t leave your battery unattended while charging
  • Don’t discharge your battery below its minimum voltage level

Project Steps

Taking Apart the Devices

Photo by Becky Stern

Taking apart anything with a lithium battery in it is dangerous. You have to be careful not to damage the battery or short it out, or you could quickly have a concentrated fire hazard on your hands. So, don’t do this at home without the supervision of someone who knows what they are doing!

I cracked open the cases using an awl and hammer to apply force to the seams in the plastic enclosures.

With the case open, the whole circuit and tank assembly usually slides right out. If it doesn’t, you can reach in with pliers and pull on the plastic tank — not the battery or its wires.

I recommend wearing gloves when handling and disposing of the liquid tank, and give the battery a wipe before removing them. When I didn’t, I had a hard time getting the vape juice stink out of my fingers even after washing my hands. This whole process is pretty smelly, and contact with skin or eyes can cause irritation and burning according to the FDA, so be careful.

Here are some examples of the batteries I found inside. These 280mAh (left) and 350mAh batteries (right) are about $5 retail, and perfect for wearables or other portable projects.

I desoldered them from the other circuitry, and then soldered their two wire connections to a new JST plug, with plenty of heat-shrink tubing to insulate the connections and relieve any strain on the tiny battery wires.

Charging the Batteries

To charge the batteries up, you can’t just connect them to power. You’ll need a charger circuit with appropriate settings for the size of the battery. The charger monitors the battery and fills it up gradually and safely.

Photo by Becky Stern

Some chargers have a DIP switch so you can toggle the charging rate. You should choose the fastest rate without going over the capacity of the battery. So, for example, for a 350mAh battery, I’d charge at 300mA. Others have solder pads you can bridge to set the charging rate (below) — I chose 200 for the 280mAh batteries.

Photo by Becky Stern

The large-capacity vape devices are nice for reusing because they come with a charging circuit. It’s been interesting to see that charging chips vary quite a bit. Some have integrated overvoltage and overcurrent protection in the chip, but others just put a couple of PNP transistors on there and call it a day. Depending on the quality of the included charge circuit, you may wish to use it … or lose it.

CT scan of a larger capacity vape. Photo by Becky Stern

Protection Circuitry & Safety

The difference between reclaimed vape batteries and the nicer ones you might buy is the protection circuitry, or lack thereof. Lithium batteries can be damaged if they are drained or charged too much or too fast. Good hobby batteries will have a little circuit on them that cuts off the power when their voltage dips too low, and protects against shorts and dangerously high current with an overcurrent cutout. These vape batteries usually don’t have any of that, so you need to add that circuitry yourself or leave the battery connected to a charger that has protection circuitry built-in, and is set to the proper charging rate for your battery.

Heat shrink tubing protects the wires, but be very judicious in applying heat to batteries. Photo by Becky Stern

To protect against accidental short circuits after the battery is out of the enclosure, I added some tape and heat-shrink to the exposed contacts. Obviously, it’s not a great idea to be adding any amount of heat to these batteries, so I was very judicious.

Electrical tape isn’t great, but it’s better than nothing. Photo by Becky Stern

Electrical tape isn’t the best kind, either. You should use high-temperature Kapton tape, but electrical tape is still better than just chucking all these bare batteries in a box together.

When the device designers put these together, they knew the current draw would never exceed that of the air sensor and heater. But when you’re reusing these batteries, thermal runaway could be a real concern — if your circuit draws more current than it is rated for (the conservative rule of thumb is the battery capacity per hour), you could start an unstoppable chain reaction inside the battery that causes it to explode. Remember the Samsung Galaxy Note 7?

In conclusion, I encourage you to pick these devices up if you see them littered, and at least get them to proper e-waste recycling, and maybe use them to power your next solar device.


This article was adapted from and appeared in Make: Volume 87.