Review on ETpower® Bicycle Waterproof HeadLight Lighting by Brian Wersching

Summary: A luminous flux of 5000 lm is simply a lie. Expect light closer to 750lm - maybe even 850lm. First, let me give you an idea of what 5000 lumens actually looks like. I have a 2015 30mm x 30mm 100W quasi-isotropic LED matrix which gives about 100lm/W. At 30V it draws about 1A and outputs about 3000lm (unfortunately I can't drive it any higher due to voltage limitations in my lab power supply). With only 3,000 lumens of light output, it illuminates a corner of my room much brighter than the (indirect) morning sun and makes the rest of the room appear dark and dirty. As a further comparison, this corresponds to about 2 x 100 W incandescent lamps. When I turn on ETpower at full power and aim at the same corner, the corner definitely lights up but with the same amount of light. The top illumination is slightly higher than my 3000lm LED panel; You can definitely see where ETpower is pointing, but that's mainly because ETpower emits at a much smaller solid angle and is more bluish in hue. In general, the light is noticeably dim compared to what it should give off. When I connect ETpower to my 8.4V lab power supply, the light draws 0.750A at room temperature and about 0.74A when warmed up, for a peak output of between 6.30W and 6.2W. The highest light output per watt of an LED that I know of is 303 lm/W as set by Cree in 2014. There are almost certainly higher efficiency LEDs in the labs these days, but a quick google search turned up no results. find something. With that figure, ETpower only emits 1910 lumens. However, high power LEDs tend to be much less efficient. In 2016, Cree managed to exceed 134 lm/W in a single 12 W LED. That number is still high for such a cheap system, but when you use it it hits 844 lumens. The 800 lm output is probably correct. Compared to the "1000lm" UltraFire WF-502B (I used scary quotes because I'm sure the light from this flash will also exceed specs), ETpower again has a stronger blue cast but is actually a bit weaker (see UltraFire is on the left and ETpower on the right). Considering the price, I expected the lamp to be overpriced. However, I would be satisfied with 2500 lm. This is an extreme case of false advertising.