You are implying that there are 2 discrete states: fully charged and fully discharged. In reality, this is an infinite spectrum. You will know when the capacit

You are implying that there are 2 discrete states: fully charged and fully discharged. In reality, this is an infinite spectrum. You will know when the capacitors are actually empty. When you flip on a 2-4kW pro audio amp, you can hear the electromagnetic forces for about a second. If you have a UPS on the same circuit, it will likely trip. That is empty. During normal use, there is no such thing as empty.