Red LED don't draw as much power as the new white hot headlight ones..
It seems a plug in mains to USB converter is cheap enough, to buy one to have at both ends of your commute.
there are also replacement wall receptacles that have the USB plugs between the 2 mains power ones .
After wednesday the days start getting shorter again.
Winter I use the bike with hub dynamo powered lights. no batteries , just internally powered capacitors for stand lights at traffic stops.
Added, data point. my battery lights:
Have a triple A pair of batteries, in a tail light that came with 2, a rack & seat post mount.
headlight takes 4 double As..
....
Last edited by fietsbob; 06-19-17 at 10:03 AM.