I need to calculate the power consumption of my device. The device is composed of an esp32 board with a cellular module, powered though an OBD port. I want to have to connected to the OBD port of a car at all time and therefore I need to know its power consumption in order to prevent it from draining the car battery.
The device sends data back to a server at regular intervals. When the car is turned off, the device does enter a low power mode where the intervals are bigger. Knowing the power consumption of the device when in this mode would allow me to determine how long I have to make the intervals in order prevent battery drainage while still getting data sent regularly.
To calculate the power consumption the amplitude is needed. I believe that I can get it by cutting a OBD extension cable and connecting the cables to a multi-meter to measure the amp (I would be using a car OBD port emulator).
Edit: completed question and added details to the problem