Re: 12 volt fog lamp as headlight
just get a 18vcordless tool battery and 1hour quick charger,weighs 1/2 pound or so.will power head and tail light for many hours.
dont forget inline fuse and toggle switch or dimmer.
price:2 12 volt car lights in series=24 volts =$12
battery and charger= $45
plus extra batteries are only like $20 and they last for 1 year or 2+