In most of states TC is cargo and if cargo extends past licence plate, the plate should be moved to visible spot.
Transponders don't have any batteries. They operate on passive chip.
Some of us might not like the idea, that each toll gate has strong magnetic field we are crossing.
But it is the same with electronic car keys. Just lately I bought a tester for electronic ignition. Passive coil with LED light on it. You put it over ignition switch and when you insert electronic knob, the ignition switch activate magnetic field to turn on the light.
