wireless data logger temperature and humidity

It depends heavily on the tunnel lining and bends. With a 433 MHz LoRa module and a line-of-sight path, you can get a kilometer or more. Inside a curved tunnel with steel ribs and shotcrete, the range drops—maybe 100–200 meters before you need a repeater. We usually conduct a site survey first to recommend a placement plan, or we supply mesh-capable nodes that relay data to a gateway outside.

Condensation is a common issue in high-humidity environments like tunnels and basements. Our standard humidity sensors have a recovery time spec—usually they return to normal readings within a couple of hours after drying out. For sites with constant saturation, we can swap in a heated sensor element or use a sintered metal filter cap that slows moisture ingress.

The logger sends a low-battery alarm well before it shuts off—typically at 10% remaining, which gives you weeks of headroom. If access is difficult, like inside a completed lining, some clients install a backup battery pack or use a logger with a solar panel port. For critical applications, we also offer loggers with swappable battery cartridges so you can hot-swap without unsealing the unit.

Most of our loggers output readings via Modbus TCP, HTTP POST in JSON format, or MQTT. If your software supports any of these, integration is straightforward. We also maintain a simple cloud portal where you can view trends and download CSV files. For older SCADA setups, we can provide an RS-485 output option with a local gateway.

The standard model operates down to -40°C, but the battery capacity drops significantly in extreme cold—expect half the normal lifespan at -20°C. For freezer monitoring, we recommend an external probe that puts the sensor inside the cold zone while the logger sits outside, plus a lithium-thionyl chloride battery that handles low temperatures better.