I am working on a project in which I need to find the optimal number of LEDs to install into a sun visor mirror in a car. By optimal I am mainly referring to a sufficient amount of lighting that is energy efficient and does not heat up after 5~10 minutes of continuous use. Any one has any experience with this? First I want to know how much lighting (lumens) is ideal for this application? Then I want to know what is the most suitable LED for this job? So far I don't have much information to work off of, I have my input current and voltage values, but that's about it.