The Truth About Lumen Ratings

J.W. Speaker also has a number of LED headlights (including an 8900 model that fits directly into XJ Cherokees) and auxiliary lights that are different than most of the conventional off-road lights the industry sees. The TS3000 driving lights (pictured) combine high-tech optics with LED lighting technology.

J.W. Speaker also has a number of LED headlights (including an 8900 model that fits direct

The other major factors that raw lumen output figures fail to take into account are the current used to drive the LEDs, optical losses, and assembly variations. Driving a higher current through an LED will produce more light, but it also make the LED hotter (thus creating thermal losses and shortening the life of the LED).

Whenever light travels through or reflects off of a material (ex. optics, lens, reflector optics etc.), it loses some of its intensity. This loss of intensity is due to inherent losses internal to the material, as well as losses that occur at the surface of the material as the light travels from air through the lens and back to air. Any light that has optics, reflector optics, or a lens will fall victim to these losses — there’s no getting around it.

Couple these optical losses with assembly variations, and you’ve got an additional 20- to 50-percent decrease in light output that the raw lumen figure doesn’t account for.

This is a lightweight two-LED touch light built by Speaker that you simply slide your finger over to turn on and off. It has a two-wire harness, is light enough to be held by sticky tape, and fits easily under a dash or overhead to light the whole cab.

This is a lightweight two-LED touch light built by Speaker that you simply slide your finger over to turn on and off. It has a two-wire harness, is light enough to be held by sticky tape, and fits easily under a dash or overhead to light the whole cab.

Effective Lumens

Now that we’ve covered why raw lumens are a theoretical measure that fails to account for real-world losses, let’s talk about effective lumens. The effective lumen output is an actual measurement of light output that does take into account all of the real-world losses we’ve just discussed.

Measuring the effective lumen output of a light requires the use of high-tech photometry equipment. Because of the cost and expertise involved in conducting photometric testing, some manufacturers opt to simply use the theoretical raw lumen numbers. This makes it very difficult to make an apples-to-apples comparison between lights and often results in consumers receiving less useable light than what’s advertised to them.

To illustrate this point, let’s take a look at a practical example. LED Light A has an output rating of 2,000 raw lumens and 1,000 effective lumens. LED Light B has an output rating of 3,000 raw lumens, but only 500 effective lumens. If you were basing your decision solely on raw lumens, Light B would be the clear choice. Once you turn both lights on, however, Light A would be twice as bright as Light B. Light A is brighter because it has the higher effective lumen output.

Thanks go to J.W. Speaker for this information to help consumers make more educated decisions when buying LED lighting equipment.