Thanks for the reply, though I'm still a little confused. If the input power to the LED is 30 amps at 4.5 volts, that comes out to 135 watts. At a 50-percent duty cycle that suggests the actual power is half or 67.5 watts. Yet you stated that the radiometric (light) output is 15 watts. That implies that the LED is only operating at 15/67.5 = 22-percent efficiency. I thought LEDs were up around 80-percent. Or does that 15-watt value include the violet-green conversion loss through the blade wall's luminous layer?
You have both my sympathies and respect dealing with that 30 amp draw. At its maximum Supernova only drew 8 amps and even at that low current, compared to your beast, Ohmic losses were a real problem.
My measured efficiency for the 30 amp blue LED lightsaber is actually only 11% ( 15 watts / (30 amps x 4.5 volts) )
The Luminous devices CBT120 LED I used in the 30 amp saber is old technology compared to the blue CREE XP-E2 LED which I measured as having a maximum efficiency of 35% at its officially rated maximum current of 1 amp per LED element.
However, the absolute maximum power output of a maximally overdriven quad blue CREE XP-E2 is only 5 watts (at 6 amps), though with an efficiency of 26% at this overdrive current.
The optical output power to electrical input power efficiency of commercially available high power visible spectrum LEDs are currently in the 15% to 40% range.
The table is for 2012 data, but the efficiency values are still roughly equal to that of the current state of the art CREE and Rebel LEDs used in our sabers.
The high laboratory efficiency mentioned for experimental LEDs are often for low power devices operated under unrealistic conditions.
As an extreme example: one group created an LED that was 230% efficient when operated in the picowatt regime. They used the trick of exciting the dopants to metastable quantum levels that could be boosted to higher energy photon emitting states by absorbing thermally generated crystal lattice phonons (quantum of vibrational energy).LED's efficiency exceeds 100%