Abstract Measurement and data-logging of temperature are important in industrial application. This paper discusses the implementation of monitoring temperature of cylinder hydraulic of a heavy equipment such as excavator in the field. For monitoring the temperatures, DS18b20 sensors are used to sense the hydraulic arms in the excavator. Due to sensing moving parts such as hydraulic arms, a WiFi technology is used to transmit temperature’s data to a browser. The ESP-NOW technology from Espressif ESP32 is chosen to minimize the electrical energy drained from the Lipo’s battery. Data-logging is done in a browser environment, by using javascript, websockets , css, and html technologies. The result shows that the usage of ESP32 in monitoring the temperatures, can be used in the real-time mode for the monitoring of excavator operations. And the 20000mAh battery-based system can last for approximately a month by using ESP-NOW technology from the Espressif.