Battery for SuperNova e3 tailight
 

I usually use a SON with a supernova e3 triple in the front and an e3 tail-light in the back that plugs into a the head lamp. For various reasons I would like to run that tail light off a battery and am wondering what battery would be a good choice.

You are taking a chance of burning up the LEDs in the taillight as I believe the normal current limiting circuitry for the taillight is in the headlight. You might email Supernova and ask if what you want to do is possible. They are pretty good about answering email technical queries.

I would add that per the Supernova web site they do make a battery version of their taillight intended for use with their battery headlights. It has a connector that plugs into the battery and then the headlight cable plugs into the taillight connector apparently. No idea if any current limiting electronics are built into the taillight connector on the battery version.