Very useful. It allows you to measure the car's voltage without opening the hood. This is very important for cars like mine, in which various mechanisms are activated that consume power and distort the exact measurement. Additionally, it has an electronic recorder that stores time (date-time) - battery voltage - temperature readings every 3 minutes. When the app on your phone connects to the BT200, these measurements are automatically transferred. This data can be exported in excel format (e.g., via e-mail) to your computer. This way, you can, for example, see the overnight voltage fluctuation and draw conclusions. If you don't know how, you can import (the entire file) into chatGTP, Gemini and ask for analysis.