The old DC generators are like dragging an anchor , through the Mud, as a functional light source,
in comparison with the recent AC Bottle Alternators produced now ,By AXA and B&M.

but if you have them just for period correctness and use something else, in the Dark, fine..

+ Incandescent Screw base, 6v 2,4w bulbs are getting as rare as an 1 faced Politician .