Cold chain hardware fails in a specific order: screen first, battery second, scanner third. If your PDA project moves food or pharma through chilled and frozen zones, plan for that order of failure from the start.
The freezer problem is condensation, not cold
A device rated to −20 °C survives the freezer. The failure happens on the way out: a cold device carried into warm, humid air condenses moisture under the screen and in the USB port. Three design choices decide whether that is a non-event or a warranty claim:
- Sealed body with membrane ports — IP67 with covered ports keeps the condensation out of the electronics.
- Glove-capable touch — capacitive panels tuned for gloves and wet fingers, because picking gloves do not come off.
- No external speaker holes on the front — water pools there first.
Battery behaviour below zero
Lithium batteries lose usable capacity sharply below −10 °C. Two shifts in a frozen zone need either a high-capacity pack sized for the loss, or a removable pack swapped at the zone boundary. Hot-swap cradles in the ante-room are the cheapest uptime insurance in the building.
Logging: the part the auditor reads
The device is only half of the logging chain. The PDA must capture:
- Temperature at capture time — from the Bluetooth probe, stamped and signed, not typed in later.
- Location or zone — scanned from the rack tag, not assumed from Wi-Fi.
- Offline resilience — the freezer is the one place your Wi-Fi dies; the app and device must queue records and sync on exit.
We pre-test PDA and probe pairings against the logging apps our customers run, and quote the ante-room cradle as part of the project rather than an accessory afterthought. Send us the zone map and the app name — the configuration comes back with the quotation.
