To monitor the power usage of my electric motorcycle and appliances, I bought a Basetech EM2000. Before using it for real monitoring, I wanted to test it to get a feel for the accuracy

As a test, I used it to monitor the energy usage of my water kettle. I filled thh cooker up to the level of “5 cups” with tap water. Using a measuring beaker, I determined that this is approximately 1.2 liter of water, which is also approximately 1.2 kg.

The tap water is slightly colder than room temperature, say 14 °C (my thermometer wouldn’t register it).

Bringing the water to boiling point took 0.13 kWh according to the meter. It took around four minutes

That converts to 468 kJ. This includes heating up the element and the metal kettle itself. The energy needed to boil the water is 4.184·(100 - 14)·1.2 = 432 kJ.

Given the uncertainties involved, I would say that this is reasonably accurate.