Multiple P7 Heat Management

[LEDobsession]

Does anyone know what would be an ideal operating temperature for 8 SSC P7's?

When I run the light at 12 vdc for 10 minutes, it manages its heat output through the heatsink/body very well and there is little to no heat noticeable on the heatsink itself. When I run the light at 14 vdc (automotive power supply) for 10 minutes, it runs up to about 102 F on the heatsink. Should I be concerned about this or is that a safe temperature to run on? By the way, this is the light, if you haven't ventured over to the Automotive thread forum here.

Thanks, Trevor.

 

[Chodes]

Does anyone know what would be an ideal operating temperature for 8 SSC P7's?

When I run the light at 12 vdc for 10 minutes, it manages its heat output through the heatsink/body very well and there is little to no heat noticeable on the heatsink itself. When I run the light at 14 vdc (automotive power supply) for 10 minutes, it runs up to about 102 F on the heatsink. Should I be concerned about this or is that a safe temperature to run on? By the way, this is the light, if you haven't ventured over to the Automotive thread forum here.

Thanks, Trevor.

Have you checked spec sheet for the P7? After the effort you put into that , worth making sure it's OK.
I'd guess either an infrared thermometer or a probe to check temp really close to the LEDs would be best.
If you search for Ellie Quad P7 , I'm pretty sure Mac tested one and found it settled at 132 F.

Here ya go:

http://www.candlepowerforums.com/vb/showthread.php?t=215904


"Tested at 2.8amps via Bench Supply Temp taken at heatsink

1 Minutes 84F
2 Minutes 93F
3 Minutes 95F
4 Minutes 102F
5 Minutes 104F
6 Minutes 110F
7 Minutes 114F
8 Minutes 119F
9 Minutes 124F
10 Minutes 125F
11 Minutes 127F
12 Minutes 130F
13 Minutes 130F
14 Minutes 131F
15 Minutes 132F

Mac "

Also in that thread:

"The light stabilizes as posted at around 130f or 54C. P7 Max temp is 125C. Why would it drop down a level?

Mac "

 

[RelativeEng]

You can run the P7 at 100C (212F) safely but you will dramatically reduce light output at that temperature. If you are maintaining below 60C you are golden.

As I am sure you already know, these max temperatures are recommended for the die, not the heatsink or even the LED itself. You must account for the thermal resistance of the P7 package (8degC/W), the thermal conductivity of the thermal compound you are using, the thermal conductivity of aluminum oxide (anodized layer), and the thermal conductivity of the heat sink (AL 6061-T6). You might be reading 60C on the fins, but the junction temperature could be well over 80C.

As for using an IR thermometer, always factor in your emissivity coefficient. These types of thermometers measure infrared spectrum light coming off of a body, they do not measure "actual true" surface temperature. A better method of measurement would be to use a surface temp thermocouple with alumel and chromel conductors.

Hopefully that makes sense.

 

[LEDobsession]

Have you checked spec sheet for the P7? After the effort you put into that , worth making sure it's OK.
I'd guess either an infrared thermometer or a probe to check temp really close to the LEDs would be best.
If you search for Ellie Quad P7 , I'm pretty sure Mac tested one and found it settled at 132 F.

Here ya go:

http://www.candlepowerforums.com/vb/showthread.php?t=215904


"Tested at 2.8amps via Bench Supply Temp taken at heatsink

1 Minutes 84F
2 Minutes 93F
3 Minutes 95F
4 Minutes 102F
5 Minutes 104F
6 Minutes 110F
7 Minutes 114F
8 Minutes 119F
9 Minutes 124F
10 Minutes 125F
11 Minutes 127F
12 Minutes 130F
13 Minutes 130F
14 Minutes 131F
15 Minutes 132F

Mac "

Also in that thread:

"The light stabilizes as posted at around 130f or 54C. P7 Max temp is 125C. Why would it drop down a level?

Mac "

I have the actual PDF for the thermal properties and Im no engineer so some of it went right over my head, but I did learn some from of it.

You can run the P7 at 100C (212F) safely but you will dramatically reduce light output at that temperature. If you are maintaining below 60C you are golden.

As I am sure you already know, these max temperatures are recommended for the die, not the heatsink or even the LED itself. You must account for the thermal resistance of the P7 package (8degC/W), the thermal conductivity of the thermal compound you are using, the thermal conductivity of aluminum oxide (anodized layer), and the thermal conductivity of the heat sink (AL 6061-T6). You might be reading 60C on the fins, but the junction temperature could be well over 80C.

As for using an IR thermometer, always factor in your emissivity coefficient. These types of thermometers measure infrared spectrum light coming off of a body, they do not measure "actual true" surface temperature. A better method of measurement would be to use a surface temp thermocouple with alumel and chromel conductors.

Hopefully that makes sense.

Great response. Ill play around with it and see what I get for temp as close to the die as I can get. My temperature testing unit is an Ohmmeter with an attachable temp probe and a reading on it so, nothing too fancy but it'll give me a reasonable guess on it.

Thanks guys.