Use ED4scan

The hardware will communicate via a serial USB connection, so you need the Arduino-IDE or a serial terminal to see the output. The Arduino will transmit the data at 115200/8-N-1 Baud. You can use CoolTerm (Mac / Win) or a similar terminal. If you have not installed the Arduino-IDE and the serial port will not show up, please install the Arduino USB drivers (this is most likely on Windows).

1. Connect the USB port to your computer.

2. Open your serial monitor / terminal and watch for this dialog to come up:

3. Connect the box to the OBD port of the car and activate the CAN bus by setting the key to position I. :

4. The Smart will indicate an active CAN-Bus with a lit 'P':

This can also be achieved by unlocking the car with the remote-key. In this case the high voltage contactors are not initiated. Without the HV-system inactive you can check the condition of the 12V battery.
Please note: Recent capacity measurements are only updated with the car active (contactors closed).

5. When you get a CONNECTED message, you will see a splash screen with live data from the CAN bus. Use the CLI for further readouts, please take a look for the possible commands. Enjoy...