Originally Posted by
unterhausen
I expect that just running a taillight is ok too, except in the unique case of the supernova lights. I think most incandescent headlights were ok by themselves, I certainly never had any problem with that setup back when I used one. In fact, my sole remaining incandescent headlight doesn't have provisions for a taillight
B&M, and Spannanga both warn against running their tail lights without a headlight as the voltage regulators are in the headlight. On the other hand, I have upgraded vintage using Reflectalight LED bulbs
REFLECTALITE LIGHT BULB FINDER that have their own built in over voltage protection.