Only done the one for Zac above so maybe he can report on it please
just finished another one today I cant do runtime experiment as only have the light head and no battery .
what you get is approx 2000 lumens on full you still have three levels of output and a strobe mode
on full it will pull 3.5 amps from the battery so you should be able to workout the approx runtime from your battery specs .
medium pulls around 1.5 amps