Post by
Pescakl1 »
https://forums.nicoclub.com/pescakl1-u98038.html
Thu Nov 19, 2009 8:20 am
3, 5mm and superflux type of leds don't heat that much, high power (1, 3W and more) leds release A LOT OF heat.
If you don't stuck them to heatsinks, they will burn out almost instantly as with heat, they absorb more current which make them hotter allowing them to take more current etc... until they are overdriven and burn out. High power leds are really sensitive to current as you push the physics to its limits.That is why high power leds need to be current driven when you can only voltage drive the other small current leds (by controlling the voltage, you can, in a way, control their current). You can voltage regulate high power leds only if you are sure to feed them with less than 70-80mA, but what will be the gain compare to superflux in that case (and this is still risky to do that).
After, depending of the size of the heatsink and the current they are run at, they can become really hot, close to 200F. In an enclosed environment where you cannot evacuate the heat, you can melt a lot of stuff.
That is why, I don't want, for now, to use high power leds for constant use (sidemarker, tail light (even brakes)) but only for intermittent use (turn signal, back up lights). You can use them for constant use, but it would be better to underdrive them (around 150mA, but again, what is the gain of under using something) or use a PWM in order to control the heat (with the use of a sufficient heatsink too).