"Bill Wright" wrote in message
So many things run on 12V DC. Firstly, why has that become the standard?
Is it all because of the nominal voltage of a car battery?
I would imagine so. 12V can easily be made out of six 2V lead-acid cells
(for a car) or eight 1.5V batteries (for a portable radio etc).
I'm not sure how 5V became the standard for USB power.