@futurebird
Sorry if I misunderstand this, but if they don't have any other power source, then all the ones that light up get their power from the ring, don't they?
Since this is the case, as you state (and more or less I agree it is correcT)... I dont understand your question. Do you not already know the answer to how many? You count the ones that give off light.... I feel like im misunderstanding the question?