Refrigerated Truck & Reefer Container Temperature Monitoring

Refrigerated trucks in India range from small insulated vans used for quick-commerce and pharmacy deliveries, through 14 ft to 24 ft reefer trucks on city and regional routes, to large trailers on long national highway corridors. Most use a refrigeration unit driven from the vehicle engine or a separate diesel engine, mounted on the front of the body. Some carry a partition that splits the body into a frozen and a chilled compartment.

The body insulation, the unit capacity and the door design decide how well a truck holds temperature. A monitoring system does not change those, but it shows clearly when a truck is being asked to do more than it can.

A reefer container is a standard ISO shipping container with an insulated shell and an integral electric refrigeration unit at one end. It needs external power: from the ship at sea, from reefer plug points at ports and container freight stations, or from a clip-on or underslung generator set when it travels by road or rail. Between those power sources, the container is unpowered and relies only on its insulation.

Reefer containers are used for frozen meat and seafood, fruit and vegetable exports, chilled dairy and pharmaceuticals. Many people searching for reefer containers want to buy, lease or understand them; for monitoring, the key point is that the container unit controls air temperature, not cargo temperature.

Containers carrying fresh fruit and vegetables also need the right relative humidity, and use fresh-air vents to remove the gases that ripening produce gives off. Where humidity matters, a temperature and humidity logger such as the IBI-MTH120-CN or IBI-UTH70 records both.

A modern reefer unit can typically hold set points from well below -18 °C up to about +25 °C or higher; check the manufacturer data for your unit. The set point itself comes from the cargo. As a general guide:

A continuous record from each truck or container says a lot about the equipment, not just the load. Watch how quickly the temperature recovers after each door opening: a unit that takes much longer than the rest of the fleet usually needs a service. Regular saw-tooth peaks show defrost cycles, and a flat line close to ambient shows a unit that was switched off. A slow pull-down at the start of every trip points to missed pre-cooling.

Comparing these patterns across the fleet lets operators and reefer leasing companies plan maintenance and decide which units suit pharma or frozen work, before a failure turns into a rejected load.

A reefer unit cycles: it cools until the return air reaches the set point, then idles or modulates, and it defrosts its evaporator at intervals. The supply air is colder than the set point, the return air is warmer, and cargo packed tightly or against the doors can sit outside both. A reading from the unit display therefore describes the air at one point, not the product.

Reefers are designed to hold temperature, not to pull hot product down. Pre-cooling the empty body before loading and loading only pre-cooled product are the two habits that make the biggest difference. Door openings on multi-drop routes add heat at every stop, and the rear of the load recovers last. An independent logger probe in the product zone shows all of this, where the unit display cannot.

For owned fleets and leased reefers, fit a live logger. The IBI-MT70 reads -30 °C to +70 °C through an external stainless steel probe and sends temperature and GPS location over 4G LTE Cat-M1. The IBI-MT120-CN and IBI-MTH120-CN add an OLED display and store 90 days of readings at 15-minute sampling, the second one also logging humidity. For a two-compartment truck, the IBI-MTD120 reads two probes, each -50 °C to +120 °C, over 4G. For dry-ice and ultra-low loads, the PT100-based IBI-MT350 reads -200 °C to +350 °C.

For loads on trucks or containers you do not control, send a data logger for the reefer container with the cargo: the IBI-UT70 or IBI-UTH70 USB loggers record for up to 90 days at 10-minute intervals and produce an encrypted PDF report when plugged in, and the IP65 IBI-BTH70 can be read by Bluetooth at the dock.

Summer ambients of 45 °C on northern and western corridors, 20-hour national highway legs, border and port dwell, and dense city delivery routes put more load on a reefer than most units are rated for in temperate markets. Pharma exports and quick-commerce dark stores add tighter limits and more door openings.

The 4G loggers carry a built-in M2M SIM from Ideabytes IoT, a DOT-approved M2M service provider, and send alerts with the vehicle location, so a dispatcher can act on a rising trend. For the process side of cold chain transport, including GDP records and proof of delivery at handover, see our in-transit cold chain page.