Acebeam X70 - 40000 lm - 8*18650 - Active fan cooling

JasonWW · August 6, 2018, 9:02pm

Hoop:

JasonWW:

Hoop:

I do believe that those three little fans are about as good as useless against this kind of heat.

Not at all. Based on my calculations, it just might be able to do 40k lumens continuously. It’s kind of at the limit.

Now 30k continous is definitely doable.

So if 40k lumen is borderline, I could definitely see it doing 40k for at least 5 to 10 minutes, then step down to 30k for the rest of the batteries life.

Even this is a huge step up from the 7k continous lights we currently have.

Care to share your calculations?

Considering the XHP70.2 thermal resistance of 0.9C°/W and a max Tj operating temperature of 150°C, with 29W input, and 23°C ambient, this would mean the heatsink could be allowed to rise 100°C above ambient, yes? Though the LED output would be reduced to 85% of the rated maximum at this Tj. To maintain 85°C Tj, the heatsink would only be allowed to rise 36°C? This is probably overly simplistic. Will dig into the requisite math more later.

See this post in my active cooled lights thread.