Let me update you guys on the current state of affairs. In many applications where LEDs are used as flash, the LED is driven a much higher current then it was designed for.

Also LEDs DO GENERATE HEAT if you talk about high power LEDs. The small ones that are used as indicator lights obviously not.

A lighting product we developped at our company used powerLEDs at higher current, because the spec has an average power number, and also a much higher peak power number. At some point, the software failed (wasn't me!), and the LED stayed on. For a while. Then it went dead.

So, before you start spreading your facts, read up on the matter. It may very well be that the n900 flashes its LED at its peak current, above the nominal (average) power, causing them to overheat and die.

So thanks to the OP for taking the risk and letting us know they hold out pretty good

Actually, they do. A little. Plus a generated light can heat things up.

LED life is shortened by excessive heat. If you drive it hard, it won't last so long.

However, the flashlight app drives the LEDs within their specs, and at a much lower level than they are driven while flashing, so durability shouldn't be an issue.

I think LED on the N900 will probably last you 100000hours of continuously lit 24/7. My samsung LED TV last 100000hours as well with about 7-11years usage. So I guess as long you did not overpowered the damn thing, then it will not break within the next few month.

Not sure about the LED on the iPhone4 though. Apple using the cheapy LED and no hard detail specification of it. Nokia fully documented the N900 hardware and that make it safer than not knowing the limitation

It all depends on the power level they're driven at. If they heat up to more than 60-90C or so on the die, they start burning out.

As a real world example, the maglite led bulb has extra circuitry to automatically reduce power when it gets overheated. This happens after about 2 minutes, after which brightness starts to drop. Usually not noticed by the users, as humans are terirble at perceiving relative brightness.

I assume within the specs for always on (t=infinity)? Because LED specs aren't as simple as they used to be, and a spec can specify a much higher current (with a time limit).

Sorry, no time to go look the n900 specs up myself

Typical LEDs have a light efficiency of about 25 percent. Newer technology is better, but generally, that's it.

I have a lighting system at home that is custom made, featuring CREE's latest and trust me, they need large heat sinks, air flow and care. Overall, the best of them dissipate at least a quarter of pumped power in heat.

Stats vary because after a certain level the power-to-light ratio goes through the roof. Lighting systems usually are close to this limit, it's a balance between efficiency and lifetime.

I very much doubt any LED system dissipates less that 25 percent, in a lighting solution, like N900's flash. As a result, we're looking at some heat, and, not dissipated, it will heat the base and cause it to dim.

So, not only they DO heat, the first sign you are in trouble is that the light DIMS, not burns out. After 15 minutes, it could still work but only put out 80 percent the light it used to.

I usually use the backlight for the LCD for light, at least they have heat sinks, are not clumped together and have been designed to stay on for a long time.

Use a blank image of a blank browser page, crank backlight to max and enjoy.

just wanted to add here

one night where i was very sleepy, i forgot to turn off the flashlight (cam LEDs) and it burned for 5hours+.

it still works fine since it has been stated before that when you use flashlight function the LEDs are only driven at a low % of there full potential.

and i have also been making LED lights for home & flashlights for 6+ years, so i know what they can take.

On average, the N900 LED should last around 25,000 hours, and the very little heat shouldn't affect it's lifespan.

To all the performance/pics/videos jokes: The girlfriend and I almost always shower together. Doesn't mean all of them have to turn sexual. That time it was a regular shower.

On another note, thanks for all the informative posts on LED technology.