Are we really talking about "lifetime" lights?

[LEDAdd1ct]

*opens up 2012 preparation journal and scribbles notes furiously...looks over shoulder, puts journal in secret underground lair, and scurries off*

 

[ericjohn]

that is why i think LED's are okay BUT i think we need to keep PR incandescent bulbs in production; just as a backup. there would be a need for better engineering in them though that would allow PR bulbs to be driven by lithium bateeries; AAA AA C D etc, because of their long shelf life...think about it, those military MX 991/U lights use PR 6 Bulbs, the military would probably want something that is EMP proof, yet can still light up the night, though poorly. i know C and D size lithium batteries are pretty much non existent but duracell and energizer industrial alkalines can be bought in bulk and they have at least a 7 year shelf life...now all i got to do is listen to the news, and whenever i think there's an emp threat, i am going to the store and buying as many mini maglite bi pins and as many pr 2's pr 4's and pr 3's as i can.

 

[eh4]

Nah, just put a tin foil hat over the bezel end of your light and worry about other infrastructure.

 

[jh333233]

Nah, just put a tin foil hat over the bezel end of your light and worry about other infrastructure.

Tin foil is not enough imo, a lead box/safe is quite safe

 

[Helmut.G]

First thing to say, I haven't read pages 2 and 3 so this post probably won't be in context with the current discussion but here's a few things I wanna say:

1. I have a Surefire 6P that is about as old as I am or even a bit more (don't know for sure as I bought it used) that works just fine even though I managed to melt the lens.
And believe me, it has seen a lot of heavy use before I bought it. The ano is worn off completely at the edges, but that's not a problem and isn't gonna be cause aluminum forms a kind of protection layer and doesn't corrode.

2. On LED lifespans. The 50000 hour rating that many power LEDs have got means the output of the average LED will have dropped to 70% after this operation time.
BUT, this is only the case if you drive the LED at the rated current (not max spec current I think) and in a temperature-controlled environment.
Since heatsinking often is poor and LEDs are heavily overdriven the 50000 hour figure is completely useless.
Less than 5000 is probably more realistic for many average lights.

3. LED life is probably not the determining factor since there's so much electronics in our lights and the LED is actually the easiest to be replaced.
At what point will the electronics fail? I have no idea, but I guess some (maybe 1 out of 3?) of my current lights will survive.


Edit: I see talk on EMP (again)
shouldn't our flashlights be safe since they're made from metal?
Is the bezel opening really enough of a weak spot to kill the light?
does anybody have some real knowledge about this? maybe a physicist around here?

btw I got some incandescent drop-ins around so I should be good but I'd still like to know!

 

[jh333233]

First thing to say, I haven't read pages 2 and 3 so this post probably won't be in context with the current discussion but here's a few things I wanna say:

1. I have a Surefire 6P that is about as old as I am or even a bit more (don't know for sure as I bought it used) that works just fine even though I managed to melt the lens.
And believe me, it has seen a lot of heavy use before I bought it. The ano is worn off completely at the edges, but that's not a problem and isn't gonna be cause aluminum forms a kind of protection layer and doesn't corrode.

2. On LED lifespans. The 50000 hour rating that many power LEDs have got means the output of the average LED will have dropped to 70% after this operation time.
BUT, this is only the case if you drive the LED at the rated current (not max spec current I think) and in a temperature-controlled environment.
Since heatsinking often is poor and LEDs are heavily overdriven the 50000 hour figure is completely useless.
Less than 5000 is probably more realistic for many average lights.

3. LED life is probably not the determining factor since there's so much electronics in our lights and the LED is actually the easiest to be replaced.
At what point will the electronics fail? I have no idea, but I guess some (maybe 1 out of 3?) of my current lights will survive.


Edit: I see talk on EMP (again)
shouldn't our flashlights be safe since they're made from metal?

2: Agree, 50k hours is only achieved in perfect condition, usually when we use our light, it always exceed 25 degree celcius, result in shorten in life

3: For some surefire and other P60 host, yes, otherwise, unlikely
Most flashlights have its guts well-sealed and usually not easily-user-serviceable, unless you are professional modder
For example, sunwayman or olight


Is the bezel opening really enough of a weak spot to kill the light?
does anybody have some real knowledge about this? maybe a physicist around here?

btw I got some incandescent drop-ins around so I should be good but I'd still like to know!

Regarding EMP
Theres one factor called "Thickness required to stop half of the energy"
And the host is actually acting like cathode a.k.a negative terminal and its round shape(closed loop) allows induce e.m.f.
Try this at home: put your phone into a safe then dial it with your homeplug phone, ive actually tried it once and my phone still rings
The safe was simply not thick enough to stop EM wave to pass through
Another point, even guts inside planes would get affected by EMP and imagine how thick was their body, let alone the little flashlight
To prove this, youll have to sacrifice one light, try microwave it or put it on a operating IH stove
They are similar to EMP(more powerful or not? i dont know cuz i havnt experienced it, but IH stove is hopping at 2khz and maybe emp is even stronger)
By the farady's law of EM induction (or whatever)
Induced e.m.f.(Actually voltage) = change in magnetic field over time taken

 

[Helmut.G]

Slightly off topic, I was in a bookstore friday and this caught my eye on the shelves: http://angryrobotbooks.com/our-authors/dan-abnett/embedded-dan-abnett/
(the german translation, actually).

The assault rifle on the book cover has a Surefire G2 mounted on it.

Proof that we have lifetime lights (story is set several hundred years in the future)?

Actually, no, after reading the first chapters it seems that the equipment on the picture has no relation to the story and laser weaponry is what they really use.

 

[yifu]

First thing to say, I haven't read pages 2 and 3 so this post probably won't be in context with the current discussion but here's a few things I wanna say:

1. I have a Surefire 6P that is about as old as I am or even a bit more (don't know for sure as I bought it used) that works just fine even though I managed to melt the lens.
And believe me, it has seen a lot of heavy use before I bought it. The ano is worn off completely at the edges, but that's not a problem and isn't gonna be cause aluminum forms a kind of protection layer and doesn't corrode.

2. On LED lifespans. The 50000 hour rating that many power LEDs have got means the output of the average LED will have dropped to 70% after this operation time.
BUT, this is only the case if you drive the LED at the rated current (not max spec current I think) and in a temperature-controlled environment.
Since heatsinking often is poor and LEDs are heavily overdriven the 50000 hour figure is completely useless.
Less than 5000 is probably more realistic for many average lights.

3. LED life is probably not the determining factor since there's so much electronics in our lights and the LED is actually the easiest to be replaced.
At what point will the electronics fail? I have no idea, but I guess some (maybe 1 out of 3?) of my current lights will survive.


Edit: I see talk on EMP (again)
shouldn't our flashlights be safe since they're made from metal?
Is the bezel opening really enough of a weak spot to kill the light?
does anybody have some real knowledge about this? maybe a physicist around here?

btw I got some incandescent drop-ins around so I should be good but I'd still like to know!

Yes the LM80 lumen maintenance testing for Cree are not done at max current, but the XML is driven at 2A and the XP-G is driven at 1A for 6000 hours and the lumen maintenance are 98.4% and 99.0% respectively. That is 66% of the max drive current so that is some pretty amazing that the XP-G loses only 1% of its lumen output over 6000 hours of 1A driving. They extrapolate using log to get a lifespan of 60k hours to 70% of the output. So i personally wouln't worry about the LED losing light output. It would maintain useful output for at least 100 000 hours.

 

[yifu]

If you want to see the actual test results, they are here http://www.cree.com/products/pdf/LM-80_Results.pdf