Which FlashLight are you looking for? Here are some Names and Explanations for them.
As a very general estimate, a low-lumen flashlight (under 50 lumens) will run for about 20-50 hours. A flashlight with 50-150 lumens will run for about 6-12 hours on it's highest setting, and high lumen flashlight or headlamp (over 150 lumens) will run about 2-8 hours on their highest settings.
