Originally Posted by
Kingshead
Edit: OK, just checked the internet and found the eneloop's output to be 1.2 volts, this is unacceptable for use in a standard flashlight in my opinion. If the light was designed by the manufacturer to run with this reduced voltage in mind then OK, but otherwise I'll stick with the tried and true alkaline and the undiminished light output.
Alkaline voltage sags quickly under load; you'll find that you'll get far longer runtimes with an Eneloop that with Alkalines in a modern LED light. In fact most runtime tests on hobbyist sites are done with Eneloops, not Alkaline batteries. In the real world under heavy loads Eneloops beat Alkalines every time.
EDIT: Here you can find some reviews of AA lights using Eneloops. Included are lux and lumen numbers.
http://www.light-reviews.com/reviews_aa.html