How AirTag battery life shows up in location history

An AirTag runs roughly a year on a single coin cell, and the record usually thins out before it stops. A flat battery and an empty warehouse produce the same picture on a map, which is nothing at all, so the shape of the decline is what tells them apart. Change the cell before a long shipment rather than during one.

How long does an AirTag battery actually last?

Apple's figure is about a year on the standard coin cell, and that is a reasonable planning number rather than a promise. The tag spends its life broadcasting a short Bluetooth signal, which is cheap, so the drain is fairly steady regardless of how much the item travels.

What does move the number is how often the tag is asked to do the expensive things. Playing a sound and running Precision Finding both cost far more than broadcasting, so a tag you hunt for weekly will not last as long as one sitting in a crate.

For a shipment, the practical consequence is simple: a tag that is already most of a year old is a bad candidate for a three-month container crossing, because the leg you care about is the one at the end.

What does a dying battery look like in the record?

It rarely stops cleanly. The usual pattern is a decline: reports that used to arrive several times an hour in a busy area start arriving once an hour, then a few times a day, then not at all.

The tell is that the thinning happens in places that used to produce dense records. A tag reporting sparsely from a city street it once reported richly from is describing its own hardware, not its surroundings.

• Reports get sparser over days while the item stays somewhere populated.
• The last few points cluster in the busiest places on the route, because a weak signal still reaches a phone standing close by.
• The record ends and never resumes, even after the item reaches somewhere you know is full of iPhones.
• Your iPhone shows a low-battery notice for that tag, which is the one unambiguous signal in the list.

Why does a flat battery look identical to an empty warehouse?

Because both produce the same thing: no reports. A location exists only when a passing Apple device hears the tag, so silence is the outcome whether the tag stopped broadcasting or nobody came near it.

The map cannot distinguish them, and neither can we. This is a real limit of the whole approach rather than something a better recorder would solve. There is nothing to record either way.

What separates them is the run-up. A coverage gap starts abruptly when the item enters a quiet place, and ends abruptly when it leaves one. A battery failure fades in over days and never ends. If the silence began in a supermarket car park and the item has since moved through a city, the battery is the likely answer.

When should you change the battery?

Before the leg that matters, not during it. A container ship or a storage unit is the one place you cannot reach the tag, and a battery that dies in week two of an eight-week crossing costs you the arrival as well as the crossing.

1. Fit a fresh cell before pack-out, before a flight, or before the item goes into storage.
2. Do it even if the tag has not warned you. The warning arrives when the cell is nearly done, which may be after the item is sealed in a crate.
3. Check the tag reports normally for a day afterwards, while you can still get to it.
4. Write the date on the item's inventory or your own note, so next time you are not guessing.
5. Use a plain CR2032 without a bitter coating where you can; some coated cells make poor contact.

The coating point is worth knowing because it produces a confusing failure. A tag with a coated cell can appear dead or intermittent while the battery itself is full.

What happens to your recorded history when the battery dies?

Everything already recorded stays exactly as it is. The history is held on our side, not on the tag, so a flat cell ends the stream of new reports and changes nothing about the old ones.

That record remains stored, browsable, and exportable on your private timeline. A flat cell stops new reports from being logged, but your existing history is never deleted or lost.

When you fit a new cell the tag starts being heard again and new points resume. Nothing fills in the dead stretch: those reports were never created, so there is nothing for anyone to recover afterwards.