My 500lumen SSC P7 flashlight gets heat hot in 15 mins!!

I have got a SSC P7 flashlight. The manufacture stated it can be up to 900 lumen. I know the real output is around 500 lumen. I take it out for test. The beam throw is very bright and covers a big range. I like it very much. But about 20 minutes passed, the torch body got very very hot and i almost have no way to hold it any more. I am afraid if i kept holding it, the light will burn my hand. Does you guys have the some problem with high power P7 flashlight?

Any P7 flashlight recommended that won't get heat hot so fast when keeping it constant on for more than half an hour???

shows that
a) the light runs on high current and thus gives its high brightness and
b) the thermal path is good


have Your blood run quicker to push more heat away

Thats why you buy multi mode ...

After changing LED's in my MTE SSC P7 it went from 2.2-2.4A to 2.6-3A measured at the tail ..

On high it gets hot!

So take some aspirin to thin your blood , or turn down the volume .

Make sure you grip it somewhat tightly while it's still cool, that way it'll transfer heat well and is less likely to get uncomfortably hot. I like when the light heats up, makes it feel like an extension of your handoo:

What brand/model/host? The basic issue is that a P7 driven at full power pulls about 10W, of which probably 8W is wasted as heat. If there is a driver board, then assuming 85% efficiency, there is another 1.8W wasted as heat, giving a grand total of almost 10W of heat generation. It has to go somewhere. If you have a small light, there just isn't enough mass to absorb the heat and thus the light gets very hot during extended runs. Solutions include shorter runs, lower power to the LED, active cooling, which seems kind of silly for a handheld flashlight, greater heat sink mass, and-or improved heat sink design (e.g., fins).

The P7 is 20% efficient? Riiiight.

ErickThakrar said:

The P7 is 20% efficient? Riiiight.

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The theoretical maximum efficacy is 683 lm/w with yellow green light at 555nm, but for the white light, the maximum is somewhere in the neighborhood of 200-400 lm/w depending on variables like tint and which parts of the spectrum it contains. Since the P7 is roughly 70 lm/w at 2.8A, that corresponds to a light conversion efficiency of about 15-30%. 20% isn't that far off!

Too hot? feed it Alkalines! :thumbsup:

i have solarforce l900 with ssc p7, it does get hot, just below the head,
i have 3 batt version, i cant really imagine it being too hot to hold, there is like 7-8 inches of handle that is cold. i,ve seen the same light in 2 batts version, that one prbly has less of a cold handle to grab.
i had mine once on for about 1.5 hours nonestop it got hot a little bit, it was outdoors, in the winter, outside temp was 15*F.
what can you do to make it run cooler?, not much, just hold it closer to the tail were it isn't hot.

I have about 10 P7 or MC-E lights and even the custom ones get hot at around 5 minutes. In fact, even my Malkoff Tripple after 10 minutes gets almost too hot to handle. I do put tons of cooper tape for a super snug fit on all of them which might be part of the reason the bezels get hot so quick. This is a good thing.:twothumbs

M@elstrom said:

Too hot? feed it Alkalines! :thumbsup:

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I don't know... maybe the leaking chemicals will cause a burning sensation...

ErickThakrar said:

The P7 is 20% efficient? Riiiight.

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Your sig line "Ignorance is the anesthesia that numbs the pain of stupidity." is so appropo.

Along the lines of lolzertank's calculation, reference to the P7 datasheet suggests that the dominant wavelength is about 575nm (this approach works better for colored LEDs like red, blue, green, etc, rather than white, but it is instructive). For that wavelength, the CIE luminosity function gives a value of ~0.9. Thus, 100% efficiency gives 683 lm/W*0.9 = 615 lm/W. For a D flux bin P7 at 2.8A drive current, we get 800-900 lm. Thus, the required power at 100% efficiency is 800/615=1.3W to 900/613=1.5W. Assuming a Vf of [email protected] (top end of an I Vf bin P7 and bottom end of a J Vf bin P7), we get 9.8W of power draw by the P7. That gives an estimated efficiency of 1.3/9.8=13% to 1.5/9.8=15%.

This is probably a bit low since typical white LEDs also have a narrower peak at the blue end of the spectrum. So, I just go with a simple, easy to remember, round number of 20%.

ErickThakrar said:

The P7 is 20% efficient? Riiiight.

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Not all the time.., but it is possible.

My P7 P60 drop-ins D bin per datasheets specs are capable of up to 900 lumens. They only make about 350ish out the front in a 3P and 6P size hosts:candle:

On the other side of the scale my 2D Mag P7 with the same D bin and direct drive P7 w/ UCL lens and 3 C NiMH cells made 870 turn-on lumens out the front.

FYI: The 2D Mag P7 gets super hot after 10 minutes, but then it just kinda stops being so hot and stays just warm. I have run it for over 2 hours non-stop on high mode and notice the super hotness only is present in the begining when the cellls are fresh.

bigchelis said:

Not all the time.., but it is possible.

My P7 P60 drop-ins D bin per datasheets specs are capable of up to 900 lumens. They only make about 350ish out the front in a 3P and 6P size hosts:candle:

On the other side of the scale my 2D Mag P7 with the same D bin and direct drive P7 w/ UCL lens and 3 C NiMH cells made 870 turn-on lumens out the front.

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That's not the relevant efficiency spec of interest here. We are looking at how much of the power that is sent to the LED is wasted as heat, rather than converted to light. Just because you might measure 870 lumens on turn-on using an IS doesn't mean that the P7 is 870/900=97% efficient. It is clear that not all 10W of power sent to a P7 is converted to light. If all 10W were converted to light, you'd get far more than 800-900 lumens for a D flux bin P7 at 2.8A drive current.

Yeah even an efficient LED like the P7 is still more space heater than photon generator.

Justin Case said:

That's not the relevant efficiency spec of interest here. We are looking at how much of the power that is sent to the LED is wasted as heat, rather than converted to light. Just because you might measure 870 lumens on turn-on using an IS doesn't mean that the P7 is 870/900=97% efficient. It is clear that not all 10W of power sent to a P7 is converted to light. If all 10W were converted to light, you'd get far more than 800-900 lumens for a D flux bin P7 at 2.8A drive current.

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What I try to do in measuring efficiency is watts of power to out the front lumens.

Most of my lights are 12~15 watt lights. Some are P7, Diamond Dragon, Tripple R2's ect....

The LED light that gives me the most lumens at 15 watts is the one I consider the most efficient. It might not be the most scientific, but it is what I do.


My incandescents are the least efficient. :nana:



Back to the OP:
In the past my inexpensive direct drive SSC P7 Trustfire light turned blue after a couple hours of use. Direct drive is my favorate way to run a P7, but without heatsinking don't expect the LED to last very long. I spoke with Gene and this is the reason he stopped making those direct drive MC-E and P7 P60 drop-ins.

i wonder what is the efficiency of carbon arc projector.

bigchelis said:

What I try to do in measuring efficiency is watts of power to out the front lumens.

Most of my lights are 12~15 watt lights. Some are P7, Diamond Dragon, Tripple R2's ect....

The LED light that gives me the most lumens at 15 watts is the one I consider the most efficient. It might not be the most scientific, but it is what I do.

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Of course there are various measures of efficiencies that apply for various situations. The point I was trying to make was that the OP's flashlight was getting hot because of heat generation by the LED and the driver. In that case, you want the efficiency of converting the input power to the LED into light. The rest is wasted as heat, which is the final result of interest. Input power vs OTF lumens won't give you that information and thus your measure of efficiency is not relevant to that point I was trying to make.

Yes... 4-die emitters generate WAY too much heat for small hand held lights, when driven at high current. They should only be used for spot-on applications only, not continuous-ON. And even then the reliability and lifespan of the LED takes a hit.

bigchelis said:

I have about 10 P7 or MC-E lights and even the custom ones get hot at around 5 minutes. In fact, even my Malkoff Tripple after 10 minutes gets almost too hot to handle. I do put tons of cooper tape for a super snug fit on all of them which might be part of the reason the bezels get hot so quick. This is a good thing.:twothumbs

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I do not think it's a good thing if the torch head gets hot so quick. All the heat concentrate on the head, the p7 lamp will easily burn out. I guess the heat-sinking of your P7 is not very good.