Product Features:Easy to install on battery Real-time battery health monitor Real time display of battery level, temperature, and voltage. Automatically test cranking system Automatically test charging system. Automatically Alert notification : The voltage abnormality APP automatically sends an alarm notification of abnormality. Supports simultaneous monitoring of the status of 4 batteries : Supports multiple device connections and can simultaneously monitor four devices on the same page. Record the track, cost, and driving habits of each trip, which can be exported to an Excel file. Automatically record parking positions and provide car search function through navigation. Stores and displays historical data & Save test records . The device's historical data can be stored for up to 30 days (voltage, charging percentage, and temperature). Save data every 2 minutes. Product Functions: Compatible with all 12V vehicle batteries and installed in the car battery Real-time monitoring via mobile phone app. Check the starting system (cranking) at each engine start and check the starting voltage every hundredths of a second when the engine starts Engine start is automatically detected and check the charging and starting systems (alternator) Receive battery condition notification when you enter bluetooth range and notify mobile phone when some data is abnormal View short circuit and reverse connection protection and voltage and charge information. When the user is close to the vehicle, the app does not need to be openedList the time of each trip and check historical data graphically. Package List BM200*1 User guide*1