LED Q: will I need fans?

[jaysonsd]

Hey everyone, I've been lurking for too long and trying to jump back in w my next project.

I'm lighting my 100g w a pair of lumenbright pendants (not an enclosed canopy) but would like to try my hand at two DIY 24" supplemental strips connected to the pair in the front and back w/ magnets (assuming I CAN do that).

I didn't think I would need a fan for them, but then I was going to connect them to two 250w pendants that make a lot of heat. The pendants will sit about 13" from the surface, so I was thinking 70-80 degree optics to max spread. These LEDs would be sunrise/sunset and the pendants would be on for 6-7 hours a day.

Whatcha think?

Jayson

[JohnnyAirtime]

In my experiences;

For 1Watt LEDs; If you have LOTS of heat sink... you don't need fans

For 3Watt LEDs; Even more heat sink, and fans are recommended

For 5Watt LEDs; Fans are a must.

[usadiver]

Oh come on Johnny, you could always blow on them!

[JohnnyAirtime]

Oh come on Johnny, you could always blow on them!

uhhh... I'm not that much of a blow hard. Maybe blond... but lacking on the hot air department. Or... am I? Oh geeez... insecurities kicking in... LOL

[jaysonsd]

I was going to go w the 1.1" heatsinks from rapidled.com and cram 12 1w LEDs w optics per strip. I think that's the max.

[usadiver]

What length? Hopefully not the 12"

[Wreck_chord]

Heat is death to LED's, keeping them cool will increase the life and efficiency. That being said, if you're running just a sunset/sunrise scenario (assuming they're off the rest of the day), I don't see a serious issue with heat. Heat sinks should be enough.

[JohnnyAirtime]

if it helps.... I COOKED some LEDs with a simple heat gun, and a (too) hot heat sink.

Best to overcool, then to overheat.