Flux, L70 and thermal management

Flux, L70 and Thermal Management.

The performance of an LED varies greatly depending on the way its used. The temperature at which the LED runs is crucial in determining output and longevity. At Mike Stoane Lighting we are constantly producing lights to your exacting requirements, this means even our 'standard products' are rarely truly standard and the varying forms, finishes and end use situations impact on the running temperature of the LED.

Despite the many variables, we take performance and reliability very seriously and are confident in any claims we make. All of our LED products will provide L70 at 50,000h (that's to say 70% of initial lumen maintenance after 50,000 hours). In addition to lumen maintenance concerns, we also have to think about relative luminous flux - the varying amount of light an LED produces relative to operating temperature. The hotter an LED is running, the less immediate light it will produce.

If you look at the 'Discreet LED Types' on our website, you'll see that we advise lumen output figures for each of the LEDs we commonly use. You may ask, in light of what's said above, "how can I trust these figures?" The key is in our in-house testing standards. The lumen outputs stated are based on average initial outputs for LEDs in the warm white range at >90CRI. We design all of our fittings to ensure the LEDs run at a temperature which will ensure these averages are met, just as we ensure the LEDs will run at a temperature which, according to the LED manufacturer's data, will ensure L70 at 50,000 hours is met. In many applications these will be modest claims.

Further to this, we don't assume that out in the real world our fittings will be subject to a clinical, steady ambient temperature of 25 degrees C, as is the case under test conditions. We always allow for at least 10 degrees C 'headroom'. This means that all of our fittings are designed to withstand continual ambient temperatures of at least 35 degrees, where predicted outputs and lumen maintenance times will not be compromised. This applies for our Xicato and discreet LED products.