A coin cell is the cheapest part of a tracking accessory and the one most likely to send a customer back to a shop. For a retailer the question is not only which cell fits, but whether the cell is worth stocking as a bundled item rather than leaving the customer to guess at a supermarket shelf.

The technical answer is short, and the retail answer depends on how the product’s battery warning behaves in practice.

What size battery does an Apple AirTag use?

A CR2032 coin cell.

Apple specifies a standard CR2032 3V lithium coin cell for the AirTag, which is a widely available size rather than a proprietary battery.

Apple documents the AirTag as using a user-replaceable CR2032 battery, and the company publishes its own replacement instructions on its support site (Apple: Batteries). Because the cell is a commodity size, the practical difference between brands is the cell’s construction and its expiry date rather than its dimensions.

For a retailer, that matters commercially: a consumable with a long shelf life and a standard size can be stocked in small quantities without occupying meaningful shelf space, and it pairs naturally with the accessory it powers.

Which CR2032 variants cause problems?

Two variants create avoidable failures. Cells with a bitter coating applied to discourage swallowing can interfere with the contact in some small devices, and the coating is not visible on the packaging unless the label states it. Cells that have been stored beyond their expiry date may measure the correct open-circuit voltage and still deliver a short service life.

The practical retail rule is to stock cells from suppliers that print the coating status and the expiry date clearly, and to rotate stock by date. Where a customer reports a new cell failing quickly, the expiry date and the contact surface are the first two items to check.

How long does a CR2032 last in an accessory like this?

Service life depends on how often the device communicates and on the ambient temperature, so a published figure is an estimate for typical use rather than a guarantee. Two behaviours shorten it in practice: leaving the device far from its paired phone, which increases transmission attempts, and storing the device in a vehicle where temperature swings are large.

For a bundle, the useful specification is a shelf life and a typical service range rather than a single number, because that is what determines how often the customer returns for a replacement.

How to replace the battery safely

The replacement is mechanical and simple, and the failure mode to avoid is deforming the metal contacts by forcing the cell into place. Remove the back cover as instructed, take out the old cell without levering against the contact, fit the new cell with the positive face as shown, and close the cover until it seats.

Coin cells are a swallowing hazard, which is why child-resistant packaging and clear warning labels are part of the product rather than a marketing option. Retailers selling cells alongside electronics should follow the applicable labelling requirements for button and coin batteries in their market.

Why the low-battery warning can appear early

Reported low-battery warnings can precede the end of service by weeks, because the device estimates remaining capacity from voltage under load rather than measuring the cell directly. A cold environment or a cell with high internal resistance will trigger the warning sooner than the remaining energy would suggest.

That behaviour is a support question rather than a defect, and it is worth answering in the product page or the bundle insert: what the warning means, how long the customer has, and which cell to buy.

Retail angle: bundling coin cells with accessories

Bundling a coin cell with the accessory it powers converts a low-value consumable into a reason to buy from the same seller again, and it reduces the chance that a customer fits an unsuitable cell from a drawer. The logistics are simple: the cell’s shelf life is long, its packaging is small, and it adds little to shipping weight.

For sellers already stocking chargers and charging stations, the same counter or listing can carry the cell, a cable and a pouch. WECENT supplies charger and accessory bundles from one quality system through its OEM/ODM programme, and the accessory side of a bundle is specified in the same document as the power product rather than sourced separately.

Documentation and testing when selling batteries alongside electronics

Button and coin cells carry their own regulatory obligations, which differ from those of the electronics they accompany: child-resistant packaging, warning symbols and, in some markets, battery-specific collection and reporting duties. In the EU, battery obligations apply across the product’s life cycle (Regulation (EU) 2023/1542), and disposal guidance such as the US EPA’s on lithium batteries sets the expectation for the end of life (US EPA: Used Lithium-Ion Batteries).

Two further documents are worth keeping for a bundle: the cell’s specification sheet with its expiry and coating status, and the transit record for the packaging, which can be written against a published protocol (ISTA). Those two items answer most retailer and marketplace questions about a consumable sold alongside electronics. Where the bundle also contains an adapter, its efficiency documentation follows the market’s external power supply rules (Regulation (EU) 2019/1782).