13th October 2026By Neil Skoglund
LHT65N Use Case
A fridge that fails overnight doesn't announce itself. Someone opens it at 7am, the milk is warm, and a full day's stock goes in the bin - along with the question of how long it was out of range and whether anything already served was affected. Paper logs filled in twice a day can't answer that question. A sensor reporting every few minutes can.
This guide shows how restaurants, cafés, butchers, delis and small food retailers can use the Dragino LHT65N with Trackpac to monitor every fridge and freezer 24/7, get alerted the moment one drifts, and keep an automatic temperature record for inspections. For the regulatory background, see our UK food temperature compliance & HACCP guide.
Most wireless temperature sensors have to sit inside the appliance they're measuring. That's a problem for cold storage: a fridge or freezer is effectively a metal box, and metal is very good at blocking radio signals. Batteries also don't enjoy living at -18°C.
The LHT65N solves both problems with its 2m external temperature probe. The thin probe cable runs through the door seal, the probe tip sits inside the cabinet, and the sensor body - battery and radio included - is mounted on the outside where it has a clear signal and a comfortable operating temperature. As a bonus, the built-in sensor measures the kitchen's own temperature and humidity, so you can see when a hot kitchen is making your refrigeration work harder.
Built-in temperature
-40 to 80°C, typical ±0.3°C accuracy, 0.01°C resolution.
Built-in humidity
0 to 96 %RH, 0.04 %RH resolution.
2m external probe
-55 to 125°C. ±0.5°C from -10 to 85°C, ±2°C across the full range.
2400mAh battery
Replaceable, rated for up to 10 years depending on reporting interval.
Datalog
Stores readings when out of coverage so they can be retrieved later.
LoRaWAN EU868
Works with standard LoRaWAN gateways and the Helium network.
Specifications from the Dragino LHT65N datasheet.
Order "Trackpac Ready" sensors
Buy one LHT65N per fridge or freezer from Hexaspot and pick the Trackpac Ready option. Each sensor arrives pre-registered, so there are no LoRaWAN keys to copy around.
Scan the QR code into Trackpac
Scan the code on the sensor with the Trackpac app and name it after the appliance - "Walk-in chiller", "Bar fridge 2", "Chest freezer". Names matter: they are what shows up in the alert text at 3am.
Place the probe, mount the body
Put the probe tip on a middle shelf away from the evaporator fan and the door, where it reads the temperature your food actually experiences. Route the cable through the door gasket at the hinge side, where it's squashed the least, and mount the sensor body on the side or top of the unit.
Tag your appliances and create alert rules
Tag sensors as "Fridges" or "Freezers" and build one alert rule per tag rather than one per device - new sensors you add later inherit the rule automatically.
The goal is an alert that means something. If staff learn to ignore notifications because they fire every time a door is held open during service, the system has failed. Trackpac's alert rules give you the controls to avoid that:
For chillers, alert above 6-7°C - before the 8°C legal limit, but above normal door-opening spikes. For freezers, alert above -15°C to allow for defrost cycles and the probe's ±2°C tolerance below -10°C.
Send alerts by email, SMS or push notification to the duty manager - and use out-of-hours rules so the owner's phone only rings overnight when nobody is on site.
Use a trigger lock interval so a fridge that stays warm sends one alert and a follow-up, not a message every reading. A "resolved" message confirms when it's back in range.
A blast chiller, a display fridge and a chest freezer have very different normal ranges. Tags let each group carry its own thresholds and recipients.
Inspection-ready records
Every reading is stored, so you can show an environmental health officer a continuous temperature history instead of a clipboard with gaps.
Early warning of failing equipment
A compressor that takes longer and longer to pull back down after each door opening is telling you something. Trend graphs let you book an engineer before it fails on a Saturday night.
Get Started
One LHT65N per appliance, probe inside, sensor outside - reporting into a Trackpac dashboard with alerts to your phone.
Yes. The LHT65N's 2m external temperature probe is fed through the door seal into the fridge or freezer, while the sensor body stays outside. That keeps the LoRaWAN radio out of the metal cabinet, which would otherwise weaken the signal, and the built-in sensor reads the kitchen's ambient temperature and humidity at the same time.
The external probe reads from -55°C to 125°C. Dragino specifies ±0.5°C between -10°C and 85°C, and ±2°C across the full range, so in a -18°C freezer you should set your alert threshold with that margin in mind - for example alerting at -15°C rather than -17°C.
In England, Wales and Northern Ireland chilled food must legally be kept at 8°C or below, and the Food Standards Agency recommends running fridges at 5°C or below to give a margin. Frozen food is normally stored at -18°C or colder.
The LHT65N is available from Hexaspot, Trackpac's sister company in the Connect IoT group. Choose the 'Trackpac Ready' option and the sensor is pre-registered on Trackpac before dispatch, so you only need to scan its QR code to add it to your dashboard.
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