How hot is too hot?

I have a question on safe temperature ranges for small xpg and xml lights running on high(1.4-3.4 amps at the tailcap). With good heat transfer to the host, what would be the highest safe external temp before damage to the emmiter? I have a Romisen T601 that gets VERY hot on high, over 120F in just 4-5 min. from 75F.

Oh ya, and why do I have to keep looking up how to spell Romisen?Darn……I just did it again!!!

120F is 48C. that's not hot.

i am saying that 75C is critical for long-term

The LED and SMT components within are pretty (surprisingly) resilient and robust. I think it was Foy or JohnyMac who ran a plastic solarforce P60 host to ~210F, and it held up fine to that abuse.

I start getting a little uneasy when the light becomes to hot to comfortably hold on. 45-50C is right around that point for me.

I have had more problems with the switch and springs melting / overheating, than anything at the business end. I just recently built an MCE-P60 drop in using the East-092 driver from the HD2010. It pulls 3.8A from a panasonic CGR18650E. 2 days ago it messed up a rev-click switch in the tailcap. I think the excessive current at ~4V caused internal arcing between the contacts and disk plate. When I took the switch apart the disk had a layer of black carbon / soot on it that was giving an intermittent contact. The switch was rated for 250V / 1.8A . The light has been left on for long durations, although I think in this case its the high current combined with on-off cycling and mode flipping that caused the switch to go bad.

My TR-J12 spring melted when I ran the light on HI for ~20 minutes. This light draws up to 7A at about 6.5 volts. The smell and cell rattle gave it away immediately.

When it comes to your mom nothing is too hot :wink:

My mom has been at ground temp. since last january…thanks for ruining the mood!

Hmmm… i must be real lucky that nothing happened to mine! ever tried leaving j18 in slight drizzle on high to use as food light. can see rain water become steam on the fins….almost 1 hour…

Combo of 12v car batt + tf-3t6 on high, using as flood too also can see water evaporating on the fins!!

End up stick the fins into bottle filled with water…lol

Water is my friend. :bigsmile:

Switches seem to have higher current/voltage ratings on AC than DC. 250V 1.8A sounds like an AC rating. That switch might not be rated as high as even 1A DC. I fudge a little on either the current or the DC voltage rating of a switch but not both and try not to exceed the max power at all. A 2A-14V switch(28W) I might run at 1.5A-18V(27W) or 3A-8.4V(25W), but not at 3A-12V(36W).

I ran a UF-2220 to around 165f in just 20 minutes. I believe Cree says they are good to 150c. I’ve heard of voltage and amps killing them but not heat alone. Worse that ever happens is the LED desolders from the star.

Its the cell you need to monitor. As the body heats up so does the cell, just more slowly. Try not to let them exceed 50c for safety issues.

Long term, heat is bad for the led. It may be able to handle quite high temperatures but if you constantly do it, the phosphor will start to brown, especially around the traces. Then you lose brightness.

Generally there is no fixed outside temperature for lights because it depends on how well the heatsinking is. If you have very good heatsinking surprisingly the outside temperature will be higher than if you have poor heatsinking. The fact that the light can get to high enough temperatures to be uncomfortable to hold means you have decent heatsinking.

I know on my high powered P60 lights, without foil wrapping the light will always stay at a comfortable temperature but I’ve had led’s unsolder themselves while the light was still only slightly warm.

I use the touch test. Anything over about 130º F is getting too hot to handle so, too hot for Foy. My 980L got to 151º during testing and I let it stay there for quite a while.

Temperature at left, 4.78 amps at right. That was over a year ago and it doesn't pull over 4 amps now. I've abused the crap out of this light.


Lol, is that ^ on a dirtbike?

Does it matter?

Not one bit, huehue.

Oh my!!

I should have guessed how this thread would end up! Foy says to use “the touch test”, then we get
the picture from E1320! I think a hose down with cold water may be in order! By the way E1320, is one of the girls in your picture the chick you guys are always talking about from CPF?

Grunta? Please say you are joking. :P

I’ve seen pics of her, she’s like mid 40’s from what I remember.

Do you really think, that if she had the ASSets, she would waste them by putting up a unreliable flashlight forum?