I want to keep a device in always on
situation in the car.
I do not want the device to drain the car battery.
The car is used at least once in two days and the current consumption of my device is not that huge < 500mA .
Wiring :
I plan to keep the OBD port's +12V
disconnected, connect the OBD GND
to my device's GND
and the data lines to my device then power my device with an external battery. . I will use the 12v DC output of it.
Example of an external battery : https://www.amazon.de/dp/B07P6V7SZH/ref=sr_1_19?keywords=power+akku+generator&qid=1581438260&sr=8-19
Wire the external battery such that it's +
line connects my device and -
line connects to the OBD GND
which is now shared with my device's GND
.
Do you see any issues with that wiring ?
Thank you very much.