- what happens if we leave the OBDLink connected to the car for a long time (e.g. overnight, with the car standing still)? Is there a secondary battery that may drain?
- Is the OBD connector powered when the "ignition" key is off (I can't test this now since we have the car for limited amounts of time but I vaguely remember that it does so).
There is a 12-volt lead-acid battery that is charged from the tractionbattery and the OBD2 Pin 16 should be directly connected to the second battery (not sure if the OBD2 specifaction regualtes that). So there is allways a ~12V current (unsafe source [ger]). So if you connect a consumer to it, the lead-acid battery should drain. Maybe it is charged by the tractionbattery even if the car is off. To avoid that you could use a relais, that has your interface connected as your load circuit and the radio or something else that works with igniion on only as your controll circuit.