Color variation:
Single-LED lights applications have no such problem. Color variation is more common in multi-LED applications. LED chips from different manufacturers may have different colors, since they use different production process. Even for one companies, different LED chips from different wafers will also have slight differences. Thus color variation is irresistible for multi-LED lamps, especially for high-power LED lighting applications.
Insulation problems:
Here insulation means insulation between positive/negative of LEDs and the heat sink. So far, this issue has not been resolved fundamentally. Most producers now only can have relevant compensations, such like MCPCB.
Anti-pulse problem:
This problem still remains controversial among manufacturers. Anti-pulse problem for high-power LED lighting applications mainly shows up in cold pulses. At the moment of switch on, a small amount of LED chips will remain in a “cold state”, which will cause huge damages to these LEDs.
LED lighting attenuation and service life:
Currently, mainland and Taiwan LED manufacturers suffered a lot on this problem. Lighting attenuation is very common among high-power LED lighting applications. LUXEON claimed that their high-power LED lamps have a service life of more than 100,000 hours. But the fact is their incompetent cooling systems and drives always let them embarrass. Theoretically, high-quality LED chips may have a service life more than 100,000 hours, but should be in ideal working conditions: working temperature should maintain in a certain level, no other electrical shocks, excessive current. In practices, 100,000-hour LED lamps are infeasible, due to various restrictions from product dimensions and limited costs. What customers need are competent products with more cost-effective. If they are unable to work for a long time, we expect a lower price, vise versa.
LED drives:
At present, most LED drive circuits followed the principles of switching power suppliers. Designers only need to change a small part of the circuit to make them more suitable for LED lighting applications. Normally, LED drives use constant current control, which makes the entire circuit be oversized. This switching-technology-adapt drives have very low efficiency (less than 80%). LED lighting producers are more willing to choose the new developed high-frequency electronic drives, which have a much higher efficiency. However, some manufacturers always go after practicalities. They claimed that their drives can control as much as ten lamps simultaneously. In fact, this is a misunderstanding. Although it can be realized theoretically due to constant current, voltage peak during the switching on process will kill LED chips in an instant.