Cateye Volt series bicycle (bike, cycling)

Hello all.
I am interested in the lights. Probably a 400 for recommending to a friend and possibly getting one myself for use on the road. It needs to be something with a sensible output with a beam pattern that won’t blind others.
But I am also wondering if it possible to fit 18650 cells? Looking at the technical info I am pretty sure that is what is inside their cartridge. So interested to hear if anyone has bought or made an adaptor to fit 18650 cells in for any of the similar shape volt series