What it means
A coin cell is the flat button battery, usually a CR2032, that powers most Bluetooth tags. It is why a tag can broadcast for a year without being charged.
The capacity is tiny, so tags achieve long life by advertising infrequently rather than by having a big battery. That is the direct cause of tags flickering in and out of scans.
Coin cells fail gradually. A tag that has become unreliable rather than absent is usually running low rather than broken.
Card-format trackers use rechargeable cells instead and last months, not years, which is a real difference when choosing one.
Related terms
The other pieces of Bluetooth vocabulary that change how you search.
- Attenuation: What blocks a Bluetooth signal
- Unwanted tracking alert: How phones warn you
- Beacon: A device that only broadcasts
- BLE: Bluetooth Low Energy
- UWB: Ultra-wideband
- Bluetooth scanner for iPhone, Scan tab
- How to find something in a hotel room before you check out, Method
- Full glossary, the complete list
Common questions
How long does a Bluetooth tag battery last?
Typically a year on a CR2032, sometimes longer. Card-format rechargeable trackers last three to five months per charge.
In the app: The scan shows this value live for every device around you. Read about Bluetooth Scanner.