The other day, someone brought me a couple ofApple AirTags to inspect. Both devices had stopped working after having their batteries replaced a few days earlier.

Did both AirTags simply decide to die at the same time? Doubtful.

Also: How to find out if an AirTag is tracking you

My first clue was that they both ceased functioning shortly after the battery change. Were the new batteries faulty? No.

As it turns out, the AirTags stopped working due to a safety feature that some manufacturers are adding to their lithium coin cells. This feature is designed to prevent children from eating and swallowing these batteries.

The problem: safety coatings

Button cells might seem harmless enough, but if swallowed, they can cause serious health problems -- including permanent injury and death. These dangers can manifest in a very short time, and the batteries remain hazardous even when discharged. Therefore, it's crucial to handle these batteries with care throughout their lifecycle.

To deter babies and toddlers from putting these batteries in their mouths, some manufacturers apply a coating of a disgustingly bitter compound called Bitrex to the button cells. The coating is intended to discourage ingestion by making the batteries taste unpleasant. The inclusion of Bitrex is an important safety measure aimed at preventing accidental swallowing and the severe health risks that can follow.

Trust me, this stuff is incredibly bitter. (Yes, I've tried it, so you don't have to.)

However, a problem arises when these coated batteries are used in certain devices. One such device is the AirTag. The bitter coating can interfere with the proper functioning of the device, which is why Apple mentions it in their battery replacement instructions.

What to do? You have four options:

1. Buy batteries that don't have the bitter coating. (Not recommended, see below.)
2. Removethe battery's coating. (Not recommended, see below.)
3. Remove someof the coating. (My preferred fix.)
4. Buy AirTag-compatible batteries.

Buy batteries that don't have the bitter coating:Yes, you can probably find batteries that don't have the bitter coating. However, considering how dangerous lithium coin cells can be, I would not recommend this if there's any chance of children getting hold of them.

Also: Traveling soon? Grab Apple's AirTag 4-pack for$20 off and never lose your luggage

Remove the battery's coating:Alternatively, you can remove the coating. But again, this coating plays a crucial role in keeping young ones safe. Therefore, I'm very reluctant to suggest removing all of it. The safety of children should always come first, and the bitter coating is an important safeguard against accidental ingestion.

The fix for AirTags that stop working after a battery swap

Remove some of the coating:My solution, if you have batteries that are incompatible with AirTags, has been to remove just enough Bitrex from the battery surface to ensure the battery contact touches the metal of the button cell. This way, you maintain most of the safety coating while ensuring the battery functions properly within the AirTag.

You don't need to clear a large patch for the AirTag; remove just enough of the coating to allow the tiny contacts to touch the battery.

I use an alcohol wipe -- a lens cleaning swab or injection swab will do the job -- to clean off a small section of the coating. If you don't have swabs, a pencil eraser also works well. Just make sure not to use anything you might put in your mouth afterward!

I find that cleaning about a quarter of the button cell's outer rim is sufficient for the battery to make contact while still retaining enough of the bitter compound to discourage ingestion.

Also: The best AirTag for your wallet is flat, rechargeable, and isn't made by Apple

Next, test-fit the battery. You'll know it makes proper contact with the AirTag because the device will emit a little tune. If it works, you're done, if not, open the AirTag up again and reposition the button cell. 

For other devices, the process is similar: Ensure the contacts align with the cleaned portion of the battery.

Buy AirTag-compatible button cells

As Apple points out,Duracell is now selling CR2032 button cells listed as "Compatible with Apple AirTag" and -- as the packaging suggests -- these work straight out of the box. 

These button cells still have a coat of Biterex, but the bitterant has been applied in a way that doesn't interfere with its operation.

Button cell safety

As for how to keep children safe around button cells, here are some important steps to follow:

1. Buy quality brands: Quality brands are more likely to be built to higher standards and include safety features such as Bitrex or packaging that makes the batteries hard to access.
2. Keep batteries in their original packaging until needed: This reduces the risk of accidental ingestion.
3. Keep them out of sight: Store batteries in places that are out of reach and not easily visible to children.
4. Only remove a small portion of the bitter coating: Do this only if necessary to ensure the device functions properly, and always minimize the area cleaned.
5. Reinstall safety features: If devices have safety features on the battery compartment -- such as screws or tabs -- make sure to refit them properly after changing the battery.
6. Dispose of used button cells safely: Ensure that used batteries are disposed of in a way that they cannot be accessed by children or pets.

Also: How I created my own Apple AirTag with a Flipper Zero (and why you should)

By following these precautions, you can help prevent accidents and ensure a safer environment for children.

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