YOU CANNOT BE ELCTROCUTED BY THE
OUTPUT OF A CAR-BATTERY CHARGER.

That statement suggests a misguided interpretation of
"certainty". I doubt you've considered ALL possibilities.
"unlikely" might be a better word than "cannot" for use
in that sentence.

You're right in principle, but it's difficult to think of /any/ situation in
which 14 volts could pump enough current through a human body to kill its
owner. You'd need a net resistance (across the heart) of 140 ohms. Not
likely.