LED Basics

LED stands for Light Emitting Diode. LEDs are small semiconductors very similar to computer chips, however rather than processing data they are "programmed" to emit narrow wavelengths of light at incredibly high efficiency levels. Over the past 50 years it has been documented that LED efficiency increases 20x per decade with costs decreasing 10X over the same period. This occurrence is now known as Haitz's law, which has enabled white LEDs to become the most efficient light sources on earth at over 200 lumens per watt (2012). Similar to computer chips, LED efficiency will continue to improve with time becoming up to 20x more powerful and 10x cheaper every decade.

Unlike traditional bulbs which rely on a filament for current to pass through, a LED passes current from anode to cathode through gold wires that are bonded to the LED chip. The electrons passing through the chip recombine in holes within the chip to release energy in the form of photons. This effect is called electroluminescence.

A LED is usually small in area (less than 1 mm2), and uses integrated optical lens to shape its radiation pattern. Each chip is affixed to a heatsink slug at the solder connection point, which dissipates heat away from the chip and to a larger external heatsink. Heat is the #1 cause of failure for a LED and temperatures above 125° F will cause immediate lumen loss to the LED while speeding up light degradation.

Unlike traditional bulbs which rely on a filament for current to pass through, a LED passes current from anode to cathode through gold wires that are bonded to the LED chip. The electrons passing through the chip recombine in holes within the chip to release energy in the form of photons. This effect is called electroluminescence.

A LED is usually small in area (less than 1 mm2), and uses integrated optical lens to shape its radiation pattern. Each chip is affixed to a heatsink slug at the solder connection point, which dissipates heat away from the chip and to a larger external heatsink. Heat is the #1 cause of failure for a LED and temperatures above 125° F will cause immediate lumen loss to the LED while speeding up light degradation.

While one LED looks almost indistinguishable from the next, the efficiency of a LED in terms of lumen output can vary dramatically depending on the BIN of the LED. After a LED is produced it goes through a computerized testing machine that separates LEDs into various BINs depending on their color and lumen output. The BIN of the LED is then given a product ID code and placed for sale by the LED manufacturer. A good example of binning is demonstrated in the graph below for 630nm red LEDs offered by Luxeon.

The most efficient 630nm LED offered by Luxeon is the LXM2-PD01-0050 which emits 102 lumens at 700mA. These LEDs can be purchased in reel quantities (1000+ LEDs) for $2.36 per LED and are considered "Top-BIN" LEDs. The least efficient 630nm LED offered by Luxeon is the LXML-PD01-0030 which emits only 62 lumens (40% less) at the same 700mA drive current. These LEDs can be purchased in reel quantities for $1.54 per LED (35% less) and are considered "Low BIN" LEDs. The main difference between a high quality and cheap LED Grow Light is usually separated by the BIN of LEDs being used, giving further credence to the saying "You get what you pay for". Hydro Grow sources Top-BIN LEDs for all X-PRO LED Grow Lights despite the high costs associated with these LEDs to ensure the absolute best performance from our products.

There is a common misconception with single-chip LEDs that "Bigger is better", however this is precisely the opposite of the truth. As with all things electrical, the more current you drive through an object the hotter it will become, and with LEDs the #1 cause of failure and premature degradation is heat. While LED manufacturers around the world are working to improve the thermal handling of 5W LEDs, they are presently incapable of matching the efficiency of 3W models.

Twice a year Hydro Grow executives purchase the best 3W and 5W LEDs from leading LED manufacturers to test and document the achievements made by these companies. Of the companies on the market selling LED Grow Lights built with 5W LEDs, many of the more expensive models are using Osram LEDs. On the most recent test in February 2012, 4 different Osram LEDs were compared against another on the same test equipment used for all Hydro Grow testing. All LEDs were of the highest BIN and the highest quality offered by Osram; however the 3W models outperformed their 5W counterparts by a significant margin.

The 3W LEDs averaged 14% more light output with 33% less power consumed compared to the 5W models from the same company. While these results do not speak for all 3W and 5W comparisons, Hydro Grow has found time after time that the most efficient 5W LED can be matched in output by a competing 3W at 33% less power consumption. Companies selling LED Grow Lights with 5W LEDs are preying on the uneducated consumer who doesn't realize that more power consumed doesn't equate to more light output with 5W LED Grow Lights. It is for this reason Hydro Grow uses 3W LEDs in all X-PRO LED Grow Lights to ensure the highest output with the least power consumed.