This is the sort of thing that almost (but not quite) pushes me to support mandatory certification (enforced by patents/other IP protections) for consumer devices that use a familiar connector like USB. Consumers shouldn’t need to worry about the specific output voltage; the presence of a USB-A connector should indicate that it abides by the specification. The hacker in me hates the idea of enforcing something like t…
It seems like somehow we're used to the idea that this particular plug will only work with the device that came with it, but we assume that USB-A is USB-A. I know I do.
This does make me wonder about the USB adapter I got with my dash cam. The documentation says all over the place to pretty please with sugar on top use our adapter. I'll have to stick a meter on it. [Edit: 5.1v.]