P7 / Driver / Overheating issue

I am working on a custom bike light system. Using 2x lights (SSC P7 and a Cree) and a 7.2V 2600 mAh battery. I am having a problem with the P7 light dropping to low mode after some runtime. I think its an overheating issue as it switches to 'low' mode, then back to high after a few seconds. It continues to do this (but only after being on for a few minutes or so). I mounted the P7 using thermal glue to the lights original heatsink, but Im guessing its not enough.. Any ideas? I dont think I can buy one of the 3rd party heatsinks as the size I have may not be standard (using this light http://www.dealextreme.com/details.dx/sku.11119.). When I touch the light, it does not feel that hot.. Any ideas?

Not sure what you mean, maybe some pics of you setup will help. You need to make sure the electronics are cooled besides the LED, maybe that's the problem.

The LED itself has no control over the modes, its the driver chip. Your driver control board is whats warming up and locking up in that mode. That needs more heatsinking. There may be nothing that you can do about it except buy a separate better quality driver.

MrGman said:

The LED itself has no control over the modes, its the driver chip. Your driver control board is whats warming up and locking up in that mode. That needs more heatsinking. There may be nothing that you can do about it except buy a separate better quality driver.

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@MrGman - I should have been more clear. The driver can detect if the LED is overheating (as a result of the LED pulling more current as it gets hotter). So, I 'think' that the P7 gets hotter and starts drawing more current than the driver is providing - so to protect it, the driver switches to low mode. However, I will look to see if the driver can be heatsinked. The probem is the driver has components on both sides and does not lend itself well to being mounted..

Now that you have pointed that out, you are probably right, Its getting toasty and dropping down to a lower mode. So when it does that put it in the freezer while its running for a few minutes, say 3 minutes, open the door and see if its jumped back up to high mode. If not try it for up to 6 minutes. Don't leave it in the freezer overnight.

Another way is to put it in the freezer before you even turn it on for 5 minutes, and then take it out and run it and see if it takes longer before it drops down to a lower mode. Record the actual times before and after this test.