The run time is usually measured in the hours of work. It reveals the amount of time the flashlight illuminates your way from complete charge to 10 percent of charge. It is an incredibly important measure as you don’t want to stick in the middle of nowhere with light that is running down. Over several years of use, the run time can be decreased. However, almost all the flashlights on the list offer minimal 8 hours of work in the lowest mode. There is a runtime graph on the flashlight that reveals the current situation. Don’t wait till the charge drops below 10 percent to recharge it.