LED Buying Guide(4) - How to compare the quality of different bulbs

For those people who want to buy LED lamps, the most important question will be: how to compare the quality of one LED lamp with another? There are some many LED lamps manufacturer in the world and so many websites/seller. They all claim that their products are of the best quality. This article is the best one you should read about this topic.

A quick way to do is to calculate the lumens/watt, which is the total amount of light the lamp emits for the amount of electricity put in. The number can be calculated by dividing the bulbs wattage by the stated number of lumens. Values over 50 lumens/watt is good at the moment. 75 lumens/watt is very good and 100 lumens/watt is excellent.

A quick comparison to normal light bulbs is as follows. Please note that this is just a general comparison - some bulbs may be rated as brighter or dimmer than this.

• 18W High Power PAR38 LED Bulb Comparable amount of light to a 100W incandescent flood. 
• 9W High Power PAR30 LED Bulb Comparable amount of light to a 50W incandescent flood. 
• 3W High Power LED Bulb - Comparable amount of light as a 25W incandescent flood. 

There is also one thing should be remembered: A halogen flood bulb is more efficient than an incandescent flood and usually costs a little more. Typically for a halogen you get about 1.5x more light for the same wattage. i.e. a 20W halogen bulb gives about the same amount of light as a 30-35W incandescent flood. You can tell if it is an incandescent or halogen by reading the packaging of the bulb.

Also notice that Warm White is always less bright than Cool White. This is because in simple terms, in order to get the warm white color, the LED is coated with yellow phosphor to make it "warmer" and thus reduces the light output. Cool White LED's have "less" of a coating.

LED bulbs manufacture typically have their LED chip or die bought from one place, then assembled elsewhere where labor is cheaper. China companies can do this job very well as China is almost the world’s biggest manufacturing base. There are a number of "well known" LED chip manufacturers at the moment. If they're not in this list, chances are they are a smaller company, and are probably less reliable.

From the ones we have experience in testing, and have heard of from the hundreds of manufacturers we've dealt with, the bigger names are:

• Cree (USA), 
• Luxeon (USA), 
• Nichia (Japan), 
• Epistar (Taiwan), 
• Edison (Taiwan), 
• Seoul Semiconductor(Korea) 

You can see US companies still provide the best chips in the world and Taiwan Companies are also doing well. Here is a typical comparison of lumens direct from a manufacturer in China for a 7W LED bulb using different dies/chips:

	Epistar (Taiwan)	Luxeon (USA)	Cree (USA)
Cool White	385	315	560
Warm White	315	140	434

You can see that Cree is by far the brightest.(Comments by Janus Lighting: usually we use Epistar chips, Cree chips are also available based on your requirement) However, there are multiple factors, besides the LED chip that determine the brightness of an LED bulb including the power supply and optics (the lens or lenses that are used to diffuse the light).

One surprising example we've seen and tested is one bulb that used 9 x 3W Cree LEDs (27 Watts), while another used 6 x 3W Epistar LED(18 Watts). The lens being used in the Cree LED bulb was poor, so the light pattern was uneven and the bulb was about 30% dimmer than the Epistar bulb, even though it used about 50% more energy.

Warranty

If you're going to spend $30-100 dollars on an LED bulb make sure your investment is protected. Sure you can buy off auction sites and get them on the cheap with no warranty, and a knockoff LED chip or you can spend the money and get a good bulb with a solid warranty. Don’t settle for anything less than a two year warranty since the bulbs should last at least 4 years at 24 hours usage per day (35,000 hours).

Beam Angles

Typically you'll see bulbs in the 30 to 70 degree range. These are LED spotlights and will give a much more focused light than traditional incandescent flood lights. The best way to tell is to see an actual picture of the bulb in action since this measurement can vary widely between manufacturers. Even though you will hear comparable to a 50W flood, the LED light will in the majority of cases be more focused than a floodlight. Again the best way to tell is if the site shows you a side-by-side comparison.

If you are looking for a more dispersed light like a traditional bulb, look for a 120 degree beam angle or larger.

Start Using LEDs Now!

LEDs are not always good alternative for all bulbs. Depending on the situation, they make sense in some places more than others. The more people who adopt LEDs, the quicker prices will come down. There is no doubt that as prices come down, and efficiency/light output of the bulbs increase, in a couple of years every light bulb in the world will be an LED Light bulb and CFLs and incandescent will be a thing of the past. Incandescent lamps are prohibited in many countries right now, and there are even more countries who are making their plan to replace incandescent with LED or CFL. Comparing to CFL, LEDs are better choices as the characteristic it have. You can read related article in this website. Start Using your LEDs right now, you will surly enjoy them.