Run time on a headlamp box is not the time the lamp stays bright. Under the ANSI/PLATO FL 1 protocol it is measured with fresh batteries from 30 seconds after switch-on until output falls to 10 percent of that first reading, so a lamp still counts as running at a tenth of its opening brightness, as Bayco Products' summary of the standard states. PLATO, the trade association that maintains the standard, says the 2019 revision covers beam distance, peak beam intensity, run time, impact resistance and water penetration protection. The condition that moves the number is the energy source: Petzl's published table for the ACTIK CORE gives 625 lumens on MAX POWER with the rechargeable CORE battery and 450 lumens on the same setting with three AAA cells.
Run time ends at 10 percent of the starting output
The 10 percent endpoint is why a headlamp advertised at 625 lumens and two hours does not hold 625 lumens for two hours. Bayco's description of the FL 1 icons sets the clock running 30 seconds after switch-on and stops it when output reaches a tenth of the initial measurement, which the document calls the total time of usable light before most people change batteries. What happens between those two points is not part of the published figure, and no icon reports it.
Manufacturers that publish a level-by-level table make the shape of that curve easier to read. Petzl lists three white levels for the ACTIK CORE on the CORE battery: MAX BURN TIME at 7 lumens for 100 hours, STANDARD at 100 lumens for 7 hours with 2 hours of reserve lighting after that, and MAX POWER at 625 lumens for 2 hours. The same lamp on three AAA cells drops to 450 lumens on MAX POWER and stretches STANDARD to 10 hours with 20 hours of reserve. A single headline lumen count collapses all six of those numbers into one.
Beam distance is measured where the light reaches 0.25 lux
Beam distance under FL 1 is the distance in meters at which the light still puts 0.25 lux on the target, which Bayco compares to the light of a full moon on a clear night in an open field. That is a threshold for seeing something is there, not for reading a map or picking a line through talus.
Because the threshold is fixed, distance climbs far more slowly than output. Petzl's table rates the ACTIK CORE at 10 meters on 7 lumens, 60 meters on 100 lumens and 115 meters on 625 lumens: a 6.25-fold jump in output from STANDARD to MAX POWER moves the rated distance by less than double. Peak beam intensity, reported separately in candela, describes the brightest point in the beam and says nothing about how wide the usable pool of light is. Campsite work and route finding sit at opposite ends of that trade, which is also the reason a lamp used near a camping tent rarely needs its top setting at all.
A 4.5-watt-hour battery decides what each level costs
Example, from the manufacturer's figures. Petzl states the CORE battery at 1250 mAh and 3.6 volts, which it prints as 4.5 watt-hours: 1.25 amp-hours times 3.6 volts is 4.5. Dividing that energy by each published burn time gives the average draw the lamp sustains across the FL 1 window. MAX BURN TIME, 4.5 watt-hours over 100 hours, averages 0.045 watts. STANDARD, over 7 hours, averages 0.64 watts. MAX POWER, over 2 hours, averages 2.25 watts.
So MAX POWER burns energy about 3.5 times as fast as STANDARD while starting at 6.25 times the output, and the gap is the step-down the FL 1 endpoint permits. The arithmetic also prices the recharge: Petzl gives a 3.5-hour charging time for the same battery, and warrants the lamp for 5 years and the CORE battery for 2 years or 300 charging cycles. At the listed price of $87.95, the battery is the part with the shorter clock.
IPX4 and IPX7 are separate tests under IEC 60529
The water icon is not one rating. Bayco's document describes the FL 1 water-resistance icon as IPX4, sprayed with water from all angles, and the waterproof icon as at least IPX7, submerged to a minimum of 1 meter for 30 minutes, with both tests run after the impact-resistance drops rather than on a fresh sample. Those codes come from IEC 60529:1989 with its 1999 and 2013 amendments, titled Degrees of protection provided by enclosures.
Petzl rates the ACTIK CORE at IPX4 and describes it as weather resistant, which is the spray test and not the submersion test. Impact resistance carries its own condition: the FL 1 figure is a drop height in meters onto cured concrete, six drops, one per face of a cube, with a 1-meter minimum to earn the icon. A lamp carried loose in a hiking backpack meets neither test in the way the lab does.
Before you buy a headlamp
- The run time at each output level, not one figure, since FL 1 stops counting only at 10 percent of the opening brightness.
- The beam distance in meters next to the lumen count, measured at 0.25 lux.
- Whether the lamp accepts standard cells as well as its rechargeable pack, and the output on each.
- The battery's warranty in years and charging cycles, and the price of a replacement pack.
- The water code as printed, IPX4 for spray or IPX7 for 30 minutes at 1 meter.
- The charging time in hours and the connector type, since a cable is often sold separately.