Reverse polarity on 12v ?
Maybe
Most 12vdc would simply not work, except 12v fans would run backwards, and 12v incandescent interior RV lamps would light
Problem
The items mention use 5v internally
Reverse polarity would mess with voltage regulation on the circuit boards, creating overload conditions, If the device even turned on and worked
Did These incidents occur while parked
Are these outlets powered by RV 12v circuit?
Converter voltage could be Too High
Or
It could have A.C. voltage ripple in the DC output
Either way it would be a converter problem
