Logistics and Warehousing
Cold storage attacks radios in three ways at once: low temperature cuts usable battery capacity sharply, moving between a cold room and a warm dock condenses water inside the device, and insulated panels with metal skins block signal. Each has a specific answer.
Cold storage is one of the few environments that attacks a radio through several unrelated mechanisms at once. A device that performs perfectly in an ambient warehouse can be unreliable in a freezer hall for reasons that have nothing to do with its radio performance.
Lithium-ion cells rely on chemical reactions that slow as temperature drops. In a cold room at −18 °C to −25 °C, a pack delivers meaningfully less usable capacity than the same pack at room temperature, and the shortfall is not gradual — it presents as a radio that reports a healthy charge and then falls over.
The consequences for planning:
Higher-capacity packs help and are worth the bulk here in a way they are not everywhere.
The cold does not destroy radios. The transition does.
A device at −25 °C carried onto a loading dock at +15 °C with normal humidity condenses water on every surface, including internal ones. Repeated twice a shift, five days a week, that moisture works into the battery contacts, the accessory connector and the charging pins, and the fleet begins failing at six to twelve months with corrosion that looks like poor build quality.
What reduces it:
This is worth specifying explicitly. A supplier quoting for "a warehouse" will not price for it.
Cold store construction is insulation sandwiched between metal skins — an effective radio barrier, and an accidental Faraday enclosure.
The practical consequence is that a chilled hall usually cannot be covered from outside it, no matter how close the repeater is. Signal enters through doors and does not travel far past them, and doors are closed most of the time by definition.
The answer is a transmitting point inside: an antenna fed from the main system, or a repeater serving the cold section. Racking inside behaves as it does in an ambient warehouse — reflecting, blocking, changing with stock — so the same design discipline applies, with the added constraint that equipment mounted in the cold room must be rated for the temperature.
Antenna and cable specification deserves attention: connectors and cable jackets stiffen and can crack at low temperature, and a connection made at room temperature may not stay sealed at −25 °C.
Cold store staff wear thick insulated gloves, and that eliminates a category of devices.
What matters:
Test with the actual gloves the site uses, before ordering. This is a five-minute check that has decided more cold store fleets than any datasheet comparison.
Cold stores are sometimes started on licence-free equipment because the area seems small. It rarely holds. Insulated construction, metal racking and the need for a repeater inside the hall all push past what licence-free bands permit — no repeaters and strictly limited power — and the ceiling is structural rather than gradual.
DMR is the usual landing point, and the reasons are practical rather than aspirational: better intelligibility at low signal levels, separate talkgroups for chilled and ambient areas, user identification on emergency alarms, and lone-worker functions that matter more in a freezer than almost anywhere else.
This deserves its own paragraph. A person incapacitated in a freezer hall is in serious danger within minutes, and cold stores frequently have staff working alone in them.
Enable lone-worker timers with a timeout appropriate to the task, man-down where a fall is plausible, and an emergency alarm with a defined recipient and an acknowledgement path. Test it on the real system with the real control position — including whether the alarm is actually noticed at three in the morning.
Regulated cold chains add documentation and hygiene requirements: devices that can be cleaned to the site's standard, no loose parts, and in some facilities restrictions on what may be carried into a production area at all.
Where the stored product is flammable or the site has classified zones, ATEX certification applies as it would anywhere else, and it applies to the battery as well as the radio.
Enough to change the shift plan. Lithium-ion chemistry slows as temperature falls, and at −25 °C a pack delivers a substantial fraction less usable capacity than at room temperature. A radio rated for a twelve-hour shift on paper may not reach eight in a cold room, so cold stores issue two packs per radio and rotate them.
Condensation. A device chilled to −25 °C and carried onto a warm, humid loading dock condenses water on and inside its surfaces. Repeated daily, that moisture corrodes contacts and connectors. It is the leading cause of cold-store radio failure and it is entirely about the transition, not the cold.
Yes. Cold store panels are usually insulation between metal skins, which is an effective barrier. Coverage inside a cold room generally cannot come from outside it, so a chilled hall needs its own antenna or repeater rather than a stronger handset in the warm part of the building.
Glove operation. Cold store staff wear thick gloves and cannot use small buttons or a touchscreen. Large, well-separated keys, a PTT that can be found by feel, and an emergency button that works through a glove are what make the radio usable, and they should be tested with the actual gloves before ordering.
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