FWIW here's the specs for my Nova Bull taillight;
4.9 watts on steady @ 12.8V
1.7 watts flashing (triple burst pattern) @11.1V
Using a 1500mah 11.1V li-ion battery pack it runs for 10 hours.
Set up next to a Superflash and Niterider it drowns them both out.
I just tested my BullLed (strobe) and BullLed Luminaire. I have two red lights on the rear (1 strobe, 1 luminare) and on the front I have an Amber strobe and white Luminaire.
The white (front) Luminaire was excellant. I just it had a slightly different lense for the center LED that would produce more of a spot light. Would just need a simple lense change out. May have to send a suggestion to Nova (mfg of the BullLed).
Gotta mount the front lights a little sturdier ... they were "jiggling" alot which messed with the eyes.
The advertised current drawing at max settings for both styles is 0.35A, so being conservative and easier on the math, I use .4A draw X 4 BullLeds at max settings (steady on at 100%) would be 1.6A. So ... a 1.6AH battery pack would last an hour (at max settings).
Max settings are a little impractical so that can be extended by ... strobing the strobes, setting the luminaires to low instead of 100%, turning the luminaires off when not needed, etc.
I don't think increasing voltages make a difference in intensity because each head has it's own control circuitry ... plus they are LEDs ... not bulbs.
So ... a battery pack running 11.1v at 1.6AH vs 12.8v at 1.6AH would produce the same results in duration and intensity. So really the option for battery choice would depending on battery pack weight, size, and price.