U2 100 vs. 80 lumens?

I have searched the archives and have found very little on this (which may just be a function of my primitive search technique): What is the story on the early U2s being labeled as 100 lumens, and the later ones as 80? Did SF change something in the light, or did they just re-evaluate their lumen rating?

I recently acquired a U2, and in three locations on the box it is described as 100 lumens. The serial no., if I'm understanding this right, seems pretty low: A03509. Is this a good thing, a bad thing, or nothing?

Thanks for any help.

From what I understand from reading on these forums, the "first run" of U2s were actually putting out 100 lumens of light, but for one reason or another (runtime, cost?), Surefire decided to cut them back to 80 lumens. If I am correct, that would mean that having the old model is certainly a good thing. It seems to be pretty rare, and a tiny bit brighter than "regular" U2s.

[ QUOTE ]
AFAustin said:
I have searched the archives and have found very little on this (which may just be a function of my primitive search technique): What is the story on the early U2s being labeled as 100 lumens, and the later ones as 80? Did SF change something in the light, or did they just re-evaluate their lumen rating?

I recently acquired a U2, and in the locations on the box it is described as 100 lumens. The serial no., if I'm understanding this right, seems pretty low: A03509. Is this a good thing, a bad thing, or nothing?

Thanks for any help.

[/ QUOTE ]I just got mine last week, serial # A04875 (if I am reading it right...LOL I'm a Newb also). My paperwork in the box also claims 2-100 so I emailed the surefirehelp line. They responded that the max is 80 lumens. No other explanation as to whether the documentation is incorrect, whether they changed the LED, etc.

[ QUOTE ]
Corallis said:
From what I understand from reading on these forums, the "first run" of U2s were actually putting out 100 lumens of light, but for one reason or another (runtime, cost?), Surefire decided to cut them back to 80 lumens. If I am correct, that would mean that having the old model is certainly a good thing. It seems to be pretty rare, and a tiny bit brighter than "regular" U2s.

[/ QUOTE ]Anyone know exactly what is considered 'old' ? For example, is there a serial # cutoff? Does having a box with an instruction manual (like the OP and myself) that states 100 lumens really mean this unit is of the 'older' batch and of 100 lumens?

I wished there were a way to test out what lumens my light actually produces. any suggestions?

Hello AFAustin,

My U2 (A02806) is also a 100 lumen version according to the box.

I believe I heard that the higher number was a bit "optimistic" and it is SureFire policy to tend to understate rather than exaggerate.

Tom

I agree with Silverfox on this one. I don't think that there are great changes between 'new' and 'old' U2s, except maybe (that's my personal theory and pure speculation) a widened bin range. With top-binned Lux Vs, the U2 is 100+ lumens. However, Surefire cannot fulfill the demand with only top-binned Lux Vs.

Also, I think that the rating should be read as "Surefire guarantees that the U2 has a top brightness in excess of 80 lumens (might be in excess of 100 lumens, if you're lucky)". The downgrading happened when they noticed that the 100 claim was based on an average value of all the Lux Vs, not the minimal one, which is around 80.

Thanks, gentlemen, for your information.

Andrew

There was another thread pertaining to older/newer U2's. It seems that the older U2's have a fraction-of-a-second warm up time on the higher modes (starts on low briefly then switches up to high).

My U2 has serial number A01325 and does do this. Perhaps someone "in the know" (*cough* PK *cough*) could tell us whether there is an output difference associated with this software change.

But...If your package denotes 100 lumens and your U2 has no warm-up period, I guess the two topics are unrelated. /ubbthreads/images/graemlins/icon3.gif

-Brad

No, I dont think there were any changes besides the lumen ratings, they realized that it didnt really put out 100 lumens.

-David

When I put my U2 in the integrating sphere, I got 113 lumens on high setting. My U2 has a serial number in the 700's (can't exactly remeber as I don't have it with me).

Ian

[ QUOTE ]
Soundbox said:
When I put my U2 in the integrating sphere, I got 113 lumens on high setting. My U2 has a serial number in the 700's (can't exactly remeber as I don't have it with me).

Ian

[/ QUOTE ]

Just curious - did it hold 113 lumens for several minutes, or was that just the "insta test". I am curious how these perform as they heat up.

Hi,

Yes - it actually started off at 114 Lumens but dropped to 113 after about 1 Minute. 3 Minutes later it was still at 113 (but nearer 112). Output was slowly dropping off.

Ian

Did SF made any firmware changes on U2?

From what I have read here, I think (just my opinion) that many of the early U2's had "X" bins in them, and therefore higher Lumen ratings. I would speculate that SureFire could not get enough "X" bins to keep up with demand and had to add high-performing "W" bins to the mix, and this probably caused the de-rating to 80 lumens.

I for sure don't have an "X" bin on mine, but seems as bright as other "W" bins that I own, and my U2 does not have the short delay either, so I probably have a fairly recent unit.

Still, either using the "X" or "W" bins, the U2 is a GREAT light /ubbthreads/images/graemlins/smile.gif

Will

[ QUOTE ]
wquiles said:
From what I have read here, I think (just my opinion) that many of the early U2's had "X" bins in them, and therefore higher Lumen ratings. I would speculate that SureFire could not get enough "X" bins to keep up with demand and had to add high-performing "W" bins to the mix, and this probably caused the de-rating to 80 lumens.

I for sure don't have an "X" bin on mine, but seems as bright as other "W" bins that I own, and my U2 does not have the short delay either, so I probably have a fairly recent unit.

Still, either using the "X" or "W" bins, the U2 is a GREAT light /ubbthreads/images/graemlins/smile.gif

Will

[/ QUOTE ]How can I figure out how bright (lumens) my light really runs at?

The only way to measure Lumen output is via expensive equipment. There are two main types but the one used most often is an integrating sphere.
You need to send it to a company with an integrating sphere calibrated for white light LEDs.

There aren't that many test labs in the world and of those I don't know any that would perform a one-off test for you.

I ran some sums a while back and decided it would take many years (if ever) to turn a profit testing flashlights at price that I thought was "reasonable". I work for a test lab - we have lots of other things to spend £100,000 on so it wasn't even worth mentioning to my boss! It's not like I'm scratching around for work.

Al /ubbthreads/images/graemlins/grin.gif

I have seen five U2s so far and I can tell some.
The first change implemented from SF has been the type of lens, they moved from Pyrex to something even more transmissive.
Another change I spotted is the startup time. In the earlier U2s the light was always starting at the lowest level, and after about 0.2 sec was moving to the level selected with the dial. Late models start at the selected level immediately.
The change in the firmware has not impacted any other parameter of the flashlight, that I can discern.

The change in the lumens rating, I believe, has nothing to do with the output of "average" U2; over five samples I have seen, all puts out more than 100 lumens, with the greenest one (one of the first model produced) being over 130 lumen. You must be really out of luck to get an 80 lumen.

The output of the U2 is not decreasing due to the temperature rise. It uses a very good thermal management.

The fact that the battery tube is bored for 18650 Li-Ion or Pila 168A, makes the U2 the best choice also as rechargeable light.

I hope this helps

Anthony

Great thread guys ! ......................................... /ubbthreads/images/graemlins/wow.gif

I've only had my U2 for a few weeks and have nothing to compare it too,
however, its far brighter that anything else I have. I too have seen many
sites state that the U2 has an out put of 2 - 100 Lumens, however, I have
no idea what the output is. I have to agree with Anthony, the battery
tube takes both the 18650 or the Pila 168A Li-ion rechargeable batteries.
A definite advantage. As a Haz Mat Specialist I have chosen to run my
U2 on the Pila protect cell. In the early 80's I had to responded to more
the one research lab explosion involving Lithium batteries. I have also
seen both military and civilian equipment that was destroyed by a
Lithium battery explosion. Although I haven't had to deal with this type
of a hazard for many year, I feel a little more comfortable using the Pila
protected cell.

Imago Metrics has a great review of the U2 at the following site ............
http://www.imagometrics.com/FLReviews/FLR_SFU2.htm

This flashlight stuff is intoxicating .......... /ubbthreads/images/graemlins/happy23.gif

I just got mine...and really like this light...says 2-100 lumens... number is A00382 but then, I don't know what 80 or even 100 lumens is supposed to look like...I can say it's BRIGHT.

My lowest serial number U2 is in the 400's. It was also the dog of the bunch, noticeably dimmer than the other two I have, and it only gave about 1100 lux at the hotspot (my brightest, a greenie, gave 2100 lux and someone has reported one as high as 2500 lux).

I have since replaced the emitter in the 1100 lux light with a nice WWOT LuxV. Its brightness improved to about 1500 lux, but it is still the underperformer of the three I have. I've decided that the problem is with the reflector. This particular sample has a much less reflective reflector than the other two 'later' U2 lights I have. Its pretty obvious looking at it with the light off and comparing the reflector surface to the others, and I don't doubt the difference is worth at least a couple hundred lux in the hotspot, maybe more. Still, it makes a very nice light.

In the ideal world I could get a 'new' shinier reflector from Surefire, but I'm pretty sure they won't sell that part alone.