Home & Office
Why you can trust ZDNET : ZDNET independently tests and researches products to bring you our best recommendations and advice. When you buy through our links, we may earn a commission. Our process

'ZDNET Recommends': What exactly does it mean?

ZDNET's recommendations are based on many hours of testing, research, and comparison shopping. We gather data from the best available sources, including vendor and retailer listings as well as other relevant and independent reviews sites. And we pore over customer reviews to find out what matters to real people who already own and use the products and services we’re assessing.

When you click through from our site to a retailer and buy a product or service, we may earn affiliate commissions. This helps support our work, but does not affect what we cover or how, and it does not affect the price you pay. Neither ZDNET nor the author are compensated for these independent reviews. Indeed, we follow strict guidelines that ensure our editorial content is never influenced by advertisers.

ZDNET's editorial team writes on behalf of you, our reader. Our goal is to deliver the most accurate information and the most knowledgeable advice possible in order to help you make smarter buying decisions on tech gear and a wide array of products and services. Our editors thoroughly review and fact-check every article to ensure that our content meets the highest standards. If we have made an error or published misleading information, we will correct or clarify the article. If you see inaccuracies in our content, please report the mistake via this form.


This battery safety feature can break your AirTags (and other devices). Here's how to fix it

You could buy a special AirTag-compatible button cell, but you don't have to. Here's the safe way to fix the batteries you already own.
Written by Adrian Kingsley-Hughes, Senior Contributing Editor
Removing a small amount of the bitter coating using an alcohol wipe
Adrian Kingsley-Hughes/ZDNET

The other day, someone brought me a couple of Apple 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, designed to prevent children from eating and swallowing the 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.

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, an important safety measure aimed at preventing accidental swallowing and the severe health risks that can follow.

Close up of the bitter coating

Close up of the bitter coating

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.

Apple's instructions for changing the AirTag's battery

Apple's instructions for changing the AirTag's battery

Adrian Kingsley-Hughes/ZDNET

What to do? You have four options:

  1. Buy batteries that don't have the bitter coating. (not recommended, see below)
  2. Remove the battery's coating. (not recommended, see below)
  3. Remove some of 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 without Bitrex. Considering how dangerous lithium coin cells can be, however, 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. Again, since this coating plays a crucial role in keeping young ones safe, 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, is 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.

Removing a small amount of the bitter coating using an alcohol wipe

Remove a small amount of the bitter coating using an alcohol wipe.

Adrian Kingsley-Hughes/ZDNET

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.

AirTags battery contacts

AirTags battery contacts

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 Bitrex coat 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 you clean.
  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.

Editorial standards