FL1 Standards for Flashlights2016-12-12T14:15:05-05:00

FL1 Standards for Rating Flashlights

by David Barnett, P.E.

In 2009, an industry standard was established by the American National Standards Institute (ANSI) for rating the performance of flashlights.  This standard is known as “FL1” and provides definitions for quantifying various aspects of flashlight operation.  While specifications for drop-testing and water resistance are relatively straight-forward, the official definitions and testing methods for lumen output and runtime are not intuitive to most consumers.

Under FL1, lumen output for a given flashlight is measured 30 seconds after activation of the flashlight.  Only output at that point in time is considered.  If output changes after 30 seconds, the lumen rating is unaffected.

Runtime, as defined by the FL1 Standard, is the amount of time elapsed from initial activation of the flashlight until the instant the output drops to 10% of the lumen rating (as defined above) in continuous operation.  With this definition, a 200-lumen flashlight producing a mere 21 lumens is still considered within its “runtime” despite the fact that a user may be greatly dissatisfied with the output.

Understanding these two basic definitions and measurements, it becomes apparent how easily manufacturers can exploit the FL1 Standard.  By designing flashlights to maximize output at the 30 second mark and then subsequently dropping output drastically, manufacturers can post both impressive lumen-ratings and long runtimes.  A theoretical graph of lumen-output versus time, unscrupulously optimized to exploit the FL1 Standard, is shown in Figure 1.


Lumen-output versus time, unscrupulously optimized to exploit the FL1 Standard

Figure 1: Lumen-output versus time, unscrupulously optimized to exploit the FL1 Standard


A flashlight with the output curve shown in Figure 1 would actually receive FL1 ratings of 1,000 lumens and a 3-hour runtime!  Those not familiar with the FL1 Standard would see such numbers and likely assume that the flashlight produces a full 1,000 lumens for 3 straight hours.  Such an assumption would be incorrect and grossly naïve.  In truth, such a flashlight produces its rated output for a mere 30 seconds then drops to a disappointing 101 lumens for the remaining 2 hours 59 minutes, a far cry from what customers would expect.

Before it is presumed that no reputable manufacturer would actually exploit the FL1 standard in this manner, consider the graph shown in Figure 2.  The red line displays the output of a popular flashlight being produced today by a major manufacturer (rated at 1,000 lumens with a runtime of 2.25 hours).   The gold line displays the output of an Elzetta Charlie-Model Flashlight (rated at 900 lumens with a runtime of 1.75 hours).  By the FL1 Standard the “red” flashlight has both a higher lumen rating and a longer runtime.  Sounds great, right?  Not so fast.  After just a few minutes, the red flashlight drops its output to less than 70% of its rated value.  By contrast, the Elzetta Charlie maintains output at or above 100% of its rating for nearly an hour.  As the output curves make clear, the Elzetta Flashlight is considerably more efficient than the red model and maintains constant high output for a much longer time thereby providing the user with consistent performance in line with the user’s needs and expectations.


Figure 2: Elzetta Charlie versus Brand-X

Figure 2: Elzetta Charlie versus Brand-X


Further clouding the issue, the FL1 Standard only tests flashlights in continuous operation until batteries are depleted to the point that output drops to 10% of rated-output.  In real life, flashlights are rarely used in this way.  Actual flashlights, especially in tactical operations, are generally used in momentary bursts or relatively short durations.  Flashlights designed to exploit the FL1 Standard, as shown above, maximize initial output within the first 30 seconds of operation.  This maximized output is generally achieved by over-drawing current from the batteries.  By repeatedly cycling such a flashlight, the device continues to operate in the over-drawn condition.  Such high current draw from batteries can greatly reduce reliability and even cause serious safety issues.  It also reduces actual runtime to a fraction of the FL1 rating.

While nearly all flashlight manufacturers, including Elzetta, have adopted the FL1 Standard to provide flashlight specifications, true apples-to-apples performance comparisons are not possible using such data.  Only by analyzing output vs. time graphs (data which is generally not published by manufacturers) can meaningful comparisons be made.  With a basic knowledge of the FL1 Standard, however, consumers will be less susceptible to marketing ploys and misleading specifications.  As always, if it sounds too good to be true, it probably is.