the el chepo LED lights use a resistor to set the current to the LED. Problem One. LED's should be driven by a constant current. When the voltage goes up, with only a resistor to control current, current goes up. Then LED junction voltage goes down, further increasing current. You end up with thermal runaway, LED's can get hot enough to melt the solder joint or just fail.
Good LED lights are more expensive, driven by constant current and generally say input voltage of 10-24V or more. Down side is the poor designed ones last a long time but put our RF that can interfere with radio.
14.7V is more than enough to kill the cheap LED lights.
