Bests & Worsts Reviews from Amazon

Bought this Philips 60-Watt Equivalent A19 LED Light Bulb (2 Pack) from my local HarDware store, because the price was just unbelievable. Two LED bulbs for one Abraham Lincoln? This is even cheaper than most CFL bulbs! At this price, I suspect Philips may have cut some corners in order to keep the manufacturing cost down. Most obvious sign is that the advertised life span is only 10,000 hours, compared to 25,000 hours for most other Philips LED bulbs. The metal body (which acts as the heat sink) is much smaller compared to other Philips A19 LED bulbs (such as the Philips 430512 10.5-watt A19 LED Bulb. This has the advantage that it makes the light distribution more uniform. But smaller heat sink also means the bulb may have problem dissipating its heat generated. This appears to be exactly the case according to my observation. [Power Consumption] I measured the power consumption using my EUM-A1 Power Usage Meter (which has a resolution of 0.1W): - Initially the bulb draws 8.3 Watt, consistent with the '8.5W' rating. - After 20 minutes or so, the consumption drops to 8.0W - After 40 minutes, it stabilized at 7.5W What I suspect is that there is a thermal safety circuit in the LED bulb. When the body temperature gets too high, the control folds back the LED current to prevent it from overheating. To verify this, I changed the orientation of the bulb to face-down position. After 15 minutes, the power drops further to 7.0W and stays there. I then changed the bulb back to face-up. Now the power slowly increases back to 7.5W after 15 minutes. This shows there is a thermal protection circuit at work, because the body heats up more easily in facing down position. [Dimming Performance] The bulb is clearly advertised as "Non-Dimmable". But being an engineer, I just have to try it on a TRIAC-controlled light fixture anyway. To my great surprise, it actually works quite well. It is able to dim smoothly down to about 50% brightness, with just a faint buzzing sound. This is even better performance than some other so-called 'dimmable' LED bulbs, such as the Cree 9.5-Watt Soft White LED Light Bulb (aka 'Black-Eyed Susan'). When placed in a non-dimmed light fixture, the bulb is completely silent. [Electro-Magnetic Interference] I was unable to try this bulb in my garage door opener, because its base is slightly too fat to screw all the ways in. But by holding an AM radio close to the LED bulb, I can tell that the EMI is relatively low compared to some other LED bulbs. The CREE Black-Eyed Susan, for example, generates loud AM interference even at 5 ft away. Its EMI was so strong that it jammed my garage door remote control during my test. [Bottom Line] The new LED bulb is obviously not as well-made as all other Philips LED bulb I have tested. However, it is currently priced at around 50% that of most low-cost competitors (including the Cree 11W 4FLOW LED bulb), so it is still a great value. By the way, the 10,000 hours lifespan sounds short, but if you use this bulb 5-6 hours a day, it can still last for 5 years. By that time LED bulbs will be even cheaper and better, anyway. [Update on July 26, 2015] Added picture to show the drop in brightness after 40 minutes of operation. ]Update on Aug 1, 2015] Added picture to show the dimming performance of this bulb (even though it is officially 'Non-Dimmable').