12-16-2009, 04:51 AM
(12-16-2009, 01:14 AM)427 Cobra Wrote: LEDs don't produce heat - only light!Actually they do produce some heat, not a lot but enough to raise the temperature in a glass light globe 20 degrees over the course of 72 hours.
Most of the heat comes from the resistors but the leds also add heat.
Here is the post from HobbyTalk where I did a small experiment out find out if leds really do generate heat
Quote:I took a 60 led string of Christmas lights (bright white color) and put them in a glass dome off an outdoor light fixture, then plugged them in.
After 3 days of constant use I pulled out the trusty digital instant read lab thermometer and got the following results
Room temp at the time of reading: 70.8 degrees f.
Temp inside of the glass globe with LEDs: 91.8 degrees f.
So the LED strand raised the temp by 21 degrees.
To be fair the resister pod on the strand was in the globe as well and I'm assuming that is where most of the heat came from.
So if the resistors could be moved away from the leds and placed outside of a model then heat wouldn't be an issue???
This was done with a strand of Christmas lights in a room where the temperature remains the same day and night. The globe was placed so there was no airflow same as a sealed model.
As a follow up I removed the resistor pack from the globe after letting the setup sit unpowered for 2 days to cool down, then powered the setup.
After 24 hours the temperature was 5 degrees higher than the room temprature.
I don't think anyone would leave a models lights on for days at a time so the temp leds generate over the space of say 20 minutes is nothing to worry about.