Originally Posted by
unterhausen
.... A lot of people only use dyno headlights because battery taillights are so good.
Or if you might want a flashing option for the taillight, thus battery. I eventually got a dyno powered taillight about five years after I initially got my dynohub and headlamp.
But I still have a battery light on the bike besides the dyno powered taillight. Most of the time that I have a taillight on, it is day time and my light is flashing.