LED's have a forward voltage drop of around 1.2 or so volts. With a trailer's battery
supply of 12 volts, either a series resistor is used to drop the voltage, which wastes energy, or high speed switching transistors (IGBT), which can make some electrical
"noise". As far as an LED tv, the components used to drive the displays are already operating at low voltages, with their internal supplies adequately filtered.
The IGBT circuitry for the LED lights
is really quite small, now contained in the devices themselves. Some have better internal filtering to keep the switching "noise" contained, other are switching at frequencies that aren't as bothersome. Sometimes just adding filters to the lighting
wires helps somewhat, as the supply wires can inadvertently act as antennas for the noise.
That's as simple as I can explain it.
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