While on vacation, I needed to replace the batteries in 2 of my airtags. I bought a set of batteries, took them back to the hotel, and was perplexed that I could not get either airtag to work with the new batteries. After retrying the old batteries, i concluded the batteries must have been old and depleted.
So I went to a little further towards civilization to a CVS. Two more batteries. Same result.
Some searching here, lead me to learn that some brands of coin cell batteries have a bitterant added to them that insulates the battery where the airtags make their connection. I went to check, and sure enough. There is a small ring of something on the outer edge of the negative side.
I’m now $30 in on these tourist priced batteries, so I am determined to find a way to make them work. I saw some mention sanding or scratching the coating off. I tried using some scissors to scrape along the edge, but no dice.
Then I realized, its most likely water soluble, right? You need to the bitterant to dissolve on the tongue to be effective. Sure enough, if you take a damp paper towel and rub the negative side for 15 seconds or so, it comes right off. Popped them into the airtags and they worked perfectly.
Hopefully this helps someone else.