06: Ok, that makes sense. I did think through how it would affect the circuit if the conductor contacted both the battery and the side of the light. I should have specified better. Put the conductor on the back (negative) end of the battery. That way if it contacts the side wall it will just bypass the on/off switch on the back of your light and turn the light on.
If the conductor was on the front (positive) end of the battery and it contacted the frame of the light, and the light was turned on at the same time(The frame gets connected to the negative terminal when you click with on/off switch on), then that would create a short circuit which could damage the battery.
I'm pretty sure anyone with the knowledge of reloading, shooting, sighting in rifles, creating and operating coyote hunting bait stations.....will have the common sense to not crush a battery by torquing it too tight in a little IR illuminator. But I suppose crazy things sometimes happen....
If you want to use your short battery, You still can with a small conductor on the negative terminal (and electrical tape around the sides to hold it in place and isolate it from the frame). Use a spacer(or spacers) thick enough to make the over all battery length the same as your other battery.
If you don't want to mess with it and your other battery works fine, then that is fine too.