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LED Lights - How do they work?

LED’s or light emitting diodes, work on a completely different basis to other light sources. A diode is created when two conductive materials are placed in contact with each other. When electricity is passed through them, the atoms in one of the materials become excited to a higher energy state. The excess energy is then released to the other material making up the diode and in the process light is generated.

LED’s are much more efficient than incandescent lamps. An incandescent lamp will typically waste 98% of the energy used in the form of excess heat. A 100-watt light bulb emits about 1,700 lumens – that’s only 17 lumens per watt. A typical LED will achieve a light output efficiency of 60 – 80 lumens per watt. Outputs greater than 100 lumens per watt have been reported, usually under laboratory or optimal test conditions.

It’s a sobering thought to think that up to 98% of the energy you are using to power your lights could be being wasted in the form of unwanted heat.

LED lamps are low voltage solid-state devices that cannot operate on a standard AC current. Part of the cost of an LED lamp is the internal circuits that are required to allow them to operate on an AC circuit.

LED’s will be damaged by excessive heat.

Heat is an LED’s worst enemy. The majority of LED’s will have heat sinks and cooling fins designed to keep the LED within its temperature design parameters.

Most LED lamps deal with the heat issue in one of two ways. Some LED lamps have multiple arrays of LED’s with built in redundancy. Thus a number of the individual LED’s could fail before light output is impaired. In addition to the ‘safety in numbers approach’, some engineers believe that is easier to dissipate heat through a large number of contact points than through a single point of contact. Thus they believe that a ‘multiple array’ will be more reliable.

Other LED lamps are single ‘high power’ LED units. Here the LED is much larger and as the name suggests, there is only one of them providing the light.

Heat management in LED lamps is absolutely crucial. No amount of ‘go faster’ cooling fins will make up for a poor thermal path.

Typically LED’s are encapsulated in a transparent resin – the lens. This resin is a poor thermal conductor so the heat must be conducted away from the LED through the backside of the chip – the area that you can’t see.

If you think about an incandescent lamp, the heat produced – of which there is a lot – is transmitted straight into the atmosphere.

With an LED, although the relative heat losses are lower, but the route out can be tortuous. This can be the Achilles heel of an LED lamp.

The quoted life of an LED is based upon an operating temperature of 25 degrees centigrade. At temperatures above this, the life of an LED can be reduced – significantly.

The LED production process is complex and the technology is still relatively new – and advancing all of the time. In our view it does not pay to buy on price. It’s very easy to produce similar looking lamps that may promise the same performance, but in reality deliver a very different experience.

As a guide we believe (cp) that a multiple array LED is likely to be more reliable than single hi power LED – at the moment!

We don’t recommend the use of LED’s were they are likely to be used for more than 14 – 16 hours per day continuously. And we don’t recommend using any LED product that has a warranty of less than three years.

Click here to see why you should change to LED lights today.