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A Tale of Two Bulbs: The Importance of Quality in LED Lighting

by Christina Crow-Dufault 14 April, 2011 06:27

When shopping around for LED bulbs, it doesn’t take long to run into huge variances in price, wattage, and guarantees. Lots of people ask about the differences between them. The fact is, while the number of high-quality and high performance LED products is increasing every day, there are quite a few products out there that just aren’t built to perform or to last. 

In terms of technology, an LED bulb shares a lot more in common with a consumer electronics device than it does with a typical filament based light bulb. You wouldn’t have the same expectations of a $30 camera as you would a $300 camera, and that’s a good mindset to have when looking for an LED bulb as well. There are a number of components that are critical to a viable LED lighting product, and any bulb is only as good as its weakest link.

LED chip - The chips are what actually generate light in an LED bulb, and the type, quality, and arrangement of the chips are of critical importance. They usually are mounted onto a layer of heat-conducting material, which is sometimes referred to as a wafer. Quality chips are specifically designed for the high light output and color consistency needed for use in general lighting. They are very different than those used in lower output applications.

In addition, when chips are manufactured, they fall across a range of color temperatures and light outputs.  They are then sorted by grade in a process called binning. The best or “tightest” bins contain chips with the highest consistency in color and light output, and therefore these are the most expensive chips to buy. The most reputable manufacturers will only work with these chips in order to keep their product consistent from bulb to bulb. The rest of the bins are less expensive but are also much less consistent, these are used in many of the bargain LEDs on the market. Some of the least reputable product on the market doesn’t even use chips that are designed for lighting, and instead uses a number of low-power chips like those used in indicator lights.

Power management- The power management system, or driver, is what converts the voltage and current coming from the socket into what is used by the LED chip to generate light. It’s functionally similar to the ballasts used by fluorescent and HID bulbs. If this system is designed poorly the chip can either become overpowered, resulting in early failure, or underpowered, resulting in low light output.

Heat Management- LED chips generate heat, and this heat must be carried away from the components and dissipated, or the life of the chip and the driver assembly will be greatly reduced. This job is performed by the heat management system, which is also commonly referred to as a heat sink. A number of different heat sink designs are being used, but most are some variation of aluminum fins extending out from a metal core. Metal castings like these tend to be the industry standard, as metal conducts heat very effectively.

Lens- When light is generated by the LED chip, it is not necessarily headed in the direction where it’s needed. It is the job of the lens to focus and direct the light in order to “land” it in the proper place. The lens is particularly critical in reflector style bulbs (like PAR and MR types).

 

A Tale of Two Bulbs

Now that you have a basic idea of what makes an LED bulb work, let’s look at two LED products that are both designed to replace a halogen PAR38 up to the 90 watt range.

On the left, we have a Philips 16PAR38 LED, which we carry on our website. On the right is an LED bulb we received as a sample from a manufacturer wanting us to resell their product. We declined to carry this product, and we think you will soon see why.

The Philips bulb has a large metal heat sink (it’s the black piece in the middle of the bulb). It has a lens which looks to be specifically designed to focus the light of the 8 high-power chips that can be seen just below the lens. The entire housing was clearly designed specifically for use as an LED reflector bulb.

The other bulb does not seem to have any heat sink at all. The lens is the same as that on a halogen PAR38 and does not seem to be designed for use with an LED bulb. It has about 25-30 chips that look to be the same low-power type that are used as indicator lights, rather than anything designed specifically to be used for lighting. In fact, the entire bulb looks like it’s a few dozen LED chips installed inside of the same housing used for a halogen bulb.

Let’s see what happens when we light them up.

The Philips bulb produces a very bright and warm light. When put side-by-side with a halogen bulb, the color and quality of the light is quite comparable. The sample bulb, on the other hand, produces a dim and cool light. It’s not just “cool white”, it’s nearly blue.  What light is being produced is not directed in any meaningful way. The bulb itself is lit, but like an LED sign, there’s not much light making it any distance from the source. To put it another way, it’s light you can see but not light you can see by.

To quantify this, we lit each bulb and measured the lux (lumens per square meter) on a wall 12 feet from the bulb. We also added in a 75 watt halogen bulb for comparison. Here’s what we found:

Philips 16PAR38 LED- 368 lux

Sample LED- 26 lux

75 watt halogen PAR38- 233 lux

 

Conclusion- What we’ve presented is a very extreme comparison, a look at the very best and worst of what’s available.  This is presented not as a comparison of two products that are the same, but rather two products that are supposed to perform similarly. Keep in mind that both of these products are supposed to be able to replace a halogen PAR38.

The Philips bulb is built to last, and delivered a bright, warm white light that outperformed the 75 watt halogen we tested. The tested sample product is of very questionable construction, has an extremely poor quality of light, and produces measured light at a level far below any PAR38 halogen on the market today. Frankly, if it performs this far below expectations right out of the box, we would have to view with skepticism any manufacturer’s claims about how long this bulb will actually last.

The value of a lighting product is more than the energy you save. Among other things, it’s the quality of the lighting that you get as an end-result, and it’s the degree of confidence you can feel that a manufacturer is going to stand behind the product.

In this regard, it’s as true in LED lighting as it is elsewhere- You get what you pay for.

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