OK so the car manual says not to stick items into the car's USB port while starting the car. Like any good engineer(ing student) I tried to see what will happen if I did so, and am now the proud owner of a few dead USB sticks. So yes, the manual wasn't kidding.
Without going through the hassle of sticking an oscilloscope into the USB car ports, I presume that some kind of voltage spike must be going through the USB port when the car engine is started. What causes it? The current surge in the starter motor circuit causing an inductive current pulse in adjacent wiring from the 12V battery to the USB port?
It is somewhat tedious to remember to remove items from the USB port before starting the car, so I was wondering if we could design some kind of surge protector for the USB port to prevent it frying sensitive electronics.
Any comments on my attached circuit diagram? What capacitances and inductances would you suggest, absent any tests with an oscilloscope to quantify the surge size and times? (It is OK to over-engineer it)
Would you also recommend similarly protecting the data in/out ports of the USB output, just in case?
Regarding the question about the car model, see a similar warning from a Youtube video on another model of car. Kia USB port video