I have flown FR quite recently but have never seen this, and if they do 'demonstrate' it, they don't draw attention to it.
At FR, three cabin crew conduct the demonstration, evenly spaced throughout the cabin. Two crew start the demonstration by indicating the floor path lighting while the third crew member remains in the real galley and switches the emergency lighting system on and off repeatedly. This flashes the lights on the underside of the overhead lockers and beside the exits. Having done this, the third crew member takes their position to indicate the exit routes.
One, turning it on before each flight would at least check it would be likely to turn on for an emergency during that flight (known as reducing the "risk period").
I beleive this is included in the nightly maintenance check.
Two, if the battery cannot be easily recharged, my friend Murphy tells me it won't be recharged regularly and correctly.
I am merely cabin crew so I'm not entirely sure about this. However, one would imagine that such a vital safety system would be maintained at regular intervals.