ba dum tss 
I still want to know what they intend to do with it because multiple cells is a long time run time
Maybe he goes out on remote unlit locations on a regular basis and can’t be arsed into recharging a single-cell light often.
if you mean 2 cells worth of run time, just use a 1 cell light, and carry the other cell
it;s not any bigger or heavier
wle