# ColdTag

> A coin-cell BLE sensor tag that streams temperature live and keeps logging offline, so a cold-chain reading is never lost to a dropped connection.

- **Page** - https://iotready.com/hardware/coldtag
- **Family** - [Cold Chain](https://iotready.com/hardware/family/coldchain)
- **Form factor** - Miniature
- **Datasheet** - https://iotready.com/downloads/coldtag-datasheet.pdf

## At a glance

- **−40 to 85 °C** Sensing range
- **±0.5 °C** Accuracy
- **25,000** Buffered readings offline
- **12 months** Coin-cell battery life

Sized to travel with a sample rather than sit in a fixed installation. While
connected, temperature streams live over Bluetooth. Connected or not, every
reading is also written to an on-device buffer holding up to 25,000 readings,
which pulls back over BLE the next time a host reconnects, so a network gap or a
phone left behind costs no data.

That combination is built for the home-visit collection round-trip. A tag
travels with the vial from doorstep to lab, streaming temperature to the
collector's phone whenever it is in range, and still has a complete, timestamped
log to hand over at the lab or to an auditor if the connection ever dropped
along the way.

## Specifications

| Parameter | Value |
| --- | --- |
| SoC | nRF52-series |
| Connectivity | Bluetooth LE, Eddystone or iBeacon advertising (set at purchase) |
| Live reading | Streamed over a BLE notify characteristic while connected |
| Offline log capacity | 25,000 readings, non-volatile |
| Sensing range | −40 °C to +85 °C |
| Accuracy | ±0.5 °C |
| Battery | CR2477 lithium coin cell, 3 V, 12 months typical, field replaceable |
| Dimensions | 65 × 41 × 17 mm, 2 mounting holes |
| Platform support | Android SDK, GATT abstracted |

## Used by

- [Cold chain monitoring for Flipkart Minutes](https://iotready.com/case-studies/flipkart-cold-chain.md): Wireless sensors in every freezer, chiller and tropical zone across sourcing hubs and dark stores, with local alarms that keep working when the internet does not.