Retrofit MR16 LED problems revealed!
Singapore, 6th October 2012
After nearly a year of frustrating testing and researching I can finally share my findings and conclusions on why we have problems with LED MR16 retrofit lamps. The most significant problem being flickering issues when dimming and unexplainable shortened life of some of the LED lamps. Despite all the flowery marketing talk about the long life and the dimming ability of the LED lamps, the fact is that all of us lighting designers face these problems continuously.
While I initially started my investigations together with the manufacturers, it was becoming clearer and clearer that manufacturers were not totally fort right in their assessments and kept diverting the attention away from the lamp/ transformer combination. With sales of these lamps reported to be in the millions per month understandable, but not helpful. So I sought help from a professional and independent specialist body, an ODM (Original Design and Manufacturing) plant in Penang Malaysia, who test, design, develop and manufacture LED lamps for many major brands in the world. Their independent findings and testing results have led me to finally being able to pinpoint the root cause of all our problems. Moreover I have come to the understanding that this problem is not manufacturer specific, but applicable to all brands, worldwide! No manufacturer to date seems to be able to master the issues surrounding the use a conventional transformer with a LED retrofit lamp without seriously affecting lamp life and lamp performance! Wow!
What was tested and measured were the current and voltage generated by the lamp (LED MR16 12V GU5.3) together with the transformer and what came out as a general result is that somehow the LED technology induces a “reaction” in the conventional transformer which in return creates continuous spikes and surges as output to the lamp. These spikes over time damage the electronics in the LED circuitry and lead to flickering and plain failing of the lamp. It appears that the stronger and longer the dimming action, the faster the deterioration of the LED lamp. This also explains why in newly installed installations the problems are not immediately apparent.
While probably ok in residential applications, it has become unacceptable in professional and commercial applications. The fact is that conventional transformers are designed for conventional technology and not for LED and vice versa! Conventional transformer and new LED technology therefore do not mix, it’s a bad marriage!
Light & Learn 3-19: Screen shots of a typical conventional transformer with surge spikes compared to what an LED lamp is designed to receive. Below that a typical schematic of the retrofit situation and one of the possible remedies taking the transformer (old non-LED technology) out of the equation.