Surefire M2 with P61, very hot surface...

[RJ9]

Hello, Sorry for my english.
I just buy a Surefire M2 with Red filter and I love it! Very high quality beam color very powerfull, I much prefer than typical LED, I never see LED from surefire. The red filter WOW! Military quality the color is RED not orange like Fenix.

Is it normal when I put P61 lamps, the flashlight comes very, very hot (all body) with red filter or not? and the battery is very hot to, is good for the battery?
Thank you very much for your answers.

 

[Justin Case]

The P61 draws about 2.3 amps of current from two SureFire 123A lithium cells. That means the P61 lamp assembly is burning around 10-11 watts. That's why the P61 gets hot. And that's also why the 123A cells get hot.

See the 123A battery shootout. Some relevant quotes:

Post #1
Test Notes:
The tests at the 1.0 Amp Rate revealed a moderate battery temperature increase. The batteries ended up in the 85-88 degree F. range. The battery temperatures shot up during the 2.0 Amp Rate testing. I have my CBA set to terminate the test when the battery temperature exceeds 115 degrees F. The SureFire battery test was terminated early because the cell temperature exceeded 115 degrees. I watched the cell temperature continue to rise, after the test had been terminated, until it leveled out at 122 degrees. The SureFire cells were the only ones that exceeded 115 degrees, but all of the others were very close.

Conclusions:
These tests revealed some differences at higher current draws, but at lower levels, the differences seem minimal.

The Energizer cells were at the bottom of the pack. These were fresh cells and I am not sure what is going on with them. I would normally do additional tests on them, but I need to find a more reasonable source for them than the local store.

The eye opener for me was the temperature increase of the batteries when testing at 2 amps. I would venture an opinion that if a light draws 2 amps or more, thermal management is going to be difficult during long runs. The lamps and LED's are producing heat, and at these rates we have the batteries producing heat as well. Lithium cells have a thermal shut down protection system, and this may shed some light on why sudden shutdown occurs with some lights.

Post #22
You're not kidding, Tom. When I first tested my M6 on SF123's with the HOLA (2.5 amp draw for each stack of 3 123's) they got so hot by the end of the run that the shrink wrap was soft and almost gooey. Plus, the speed with which the light died makes me think that they went into thermal shut down. Temperature was on the order of 160F.

 

[mdocod]

Totally normal for the P61 to generate serious heat and have ~15-20 minutes total runtime even on the best cells out there.

The high output lamps from SureFire are on the blistering edge of maximum safe current draw from CR123s, and many brands of CR123s just can't handle that current well at all. The P61 should really only be used in relatively short bursts to keep the heat under control.

Maintaining those levels of output for extended periods of time is better handled by larger hosts to absorb more heat and spread out the power consumption across either larger cells, or more cells, so as to reduce the heat generated by the cells themselves.

 

[kramer5150]

Totally normal for the P61 to generate serious heat and have ~15-20 minutes total runtime even on the best cells out there.

The high output lamps from SureFire are on the blistering edge of maximum safe current draw from CR123s, and many brands of CR123s just can't handle that current well at all. The P61 should really only be used in relatively short bursts to keep the heat under control.

Maintaining those levels of output for extended periods of time is better handled by larger hosts to absorb more heat and spread out the power consumption across either larger cells, or more cells, so as to reduce the heat generated by the cells themselves.

x2... its better for spot-use only.

 

[RJ9]

The M2 run much more cooler now, because before I use a CR123 double shrink wrapped sets (TITANIUM INNOVATIONS) I just use the battery not wrapped.

 

[tebore]

The M2 run much more cooler now, because before I use a CR123 double shrink wrapped sets (TITANIUM INNOVATIONS) I just use the battery not wrapped.

I hope for your sake they don't come in contact with bare metal forming a short. If they do you have a pipe bomb in your hand.

 

[mdocod]

I hope for your sake they don't come in contact with bare metal forming a short. If they do you have a pipe bomb in your hand.

He was talking about the cells that come with a second layer of shrink-wrap holding multiple cells in a stack. Titanium is the only brand I am aware of that has this available. There is still the regular shrink wrap on the cells being used there.

-Eric