[broadgage]

I can remember being PAID to make some 6 volt Christmas lights for rich relatives.
A lit Christmas tree was wanted in the middle of the dining table for Christmas dinner without the trip hazard of a trailing wire. Power from a 6 volt vehicle battery under the table.

I also made strings of lights that give a reasonable run time from dry batteries. 2.5 volt, 0.06 amp bulbs in series pairs from a 6 volt dry battery.
20 lamps in 10 series pairs were 0.6 amps in total and give at least a dozen hours use from a 6 volt lantern battery.

For the 1970s power cuts I made some 12 volt Christmas lights with the common 12 volt, 1.1 watt bulbs wired in parallel. The red, blue, green, and orange lamps were powered from the mains via a small transformer.
The white lamps changed over to a 12 volt battery when the mains failed.
Having only one lamp in five switching to battery gave a decent run time from an old car battery, and the light was still impressive when all else was in darkness.