Now there’s the rub it is more efficient than the older leds .
No run time tests as it is Johns L&M battery so I dont know the Amp hour of it
All I know is it is a 11.1 volt Li Ion pack with 6 cells so I am quessing it is a 4.4 amp hour pack
so 48 watts capacity
the 2 XMLs are 6.5 volts and if on full 3 amps = 19.5 watts
so a runtime for John if on high would be 2.46 hours
but his batteries are old so who knows .
low and medium would be used the most with high for the registered blind 😯
so to answer your question Steve for the double ideal battery would be 11.1 volts and above a 7.4 volt would be a bit close to the VF of the leds
just measured the draw from a 15v 2.6 amp hour volt battery
37 watts capacity
low 80 Ma runtime 30 hours rideable
medium 280 ma runtime 8 hours Kin Bright
high 1400 ma run time 1 hour 45 mins WTF is that