SureFire L4/KL4 Runtime

Tonight after I get home, I want to perform a simple test to see how much of the cell the L4 really uses. I'm going to run an L4 until it drops into moon-mode, the put one of those cell in an ARC-LSH and the other in a McLux. I will note which cell goes into which light, since there's still an unanswered question as too the cell closest to the tailcap having a bit more juice in it after exhaustion. Maybe what I'll do is perform the test twice and each time change the host cells when put into the LSH and McLux. For example, in the 1st test, the McLux will get the cell closest to the bezel, the LSH will get the cell closest to the tailcap. For the 2nd test, I"ll reverse that cell configuration.

What I'm trying to prove in these tests is whether or not the LSH or McLux can draw more useful juice from the cells, after the L4 thinks he's drained them as much as possible.

Good idea. This will answer a lot of questions I have. And with this idea in hand, I'm going to do the same with my A2.

Looking forward to hearing your results.

Can't you just measure the voltage on the spent batteries to see how much juice left on each cell?

Just wondering.

OK, the 1st test was not too extensive it all, however it does answer some questions. I didn't take any measurements for this 1st round. They will come at a later time. I fired up the L4 with had 2-SureFire cells that about 10-minutes of intermitent use. I ran the light for about an hour and twenty minutes. That allowed the L4 to heat up, shift into moon mode and cool down to the touch. I let it powered-on in that condition until the body/bezel came back down to room tempature. It still had a bunch of useable light. I took one of the 123-cells and put it into the McLux and the other into the LSH-P. Upon firing them up, they came on in moon-mode with not a whole lot of usable light. Both were significally dimmer than the L4 was right before turning it off. I put the cells back into the L4 and it light much brighter than the McLux or LSH did for 10-15 minutes.

Keep in mind the point of this test. I wanted to see how well the L4 uses the cells before giving up on them. It wasn't to compare to the McLux or LSH. The McLux and LSH were used to see if they could "find" any juice that the L4 couldn't. They were unable to do that, which is really a good thing. That means the L4 IS using as much of the cells as it possibly can before giving up. I like that.

Great test, Nas. The regulation of the led is really doing its job and getting the most out of the cells.

Appreciate the test. Thanks.

I'm liking my L4 more all the time. A great product from SF.

Paul, did you get your testing started with the A2?

Ray,

You have posed two questions in your earlier post of this morning (gosh, it seems like last week):

1. Can the A2 suck more from the batteries than the Arc LS can?
2. In the A2, does one battery get more depleted than the other.

I have gotten an answer to question 1. In the time since I got the A2, I stoked it periodically with used batteries from other lights. Then when the xenon would get quite yellow -- no brighter than the LEDs -- I would take them out and use in my Arc LSHS. The Arc always lit brightly. The batteries would go into Arc moon mode after about 2 to 5 minutes. I think I measured 4 minutes one time. Unfortunately, I didn't record this in my trusty flashlight lab notebook. And I haven't kept track of the location of the cell in the A2.

So, I have determined that the Arc can suck a tiny bit nore from the batteries after the A2 has done its job. I would guess that a Rev1 Arc would get even more. Combining this with the results of your testing, it would appear that the L4 sucks more than the A2 (if you'll forgive the terminology). /ubbthreads/images/graemlins/smile.gif

Question 2 -- I don't have that answer. I'll need to be a little more rigorous to determine that. It seems that transfering batteries from another light to the A2 is not a good basis for this test. I'm going to have to bite the bullet and start fresh batteries in the A2 and run them straight through. Then they can be run in the Arc and each run time recorded.

Perhaps there will be time tomorrow. I'm just getting into too many projects. I'll let you know when I have some results.

Paul

At what point did the L4 become untouchably hot and how long did it last in regulation?

Brightnorm

Another good question... How cookin' did it get?

Is it a lot warmer/hotter than the SF E2E after 30 minutes?

My testing was done with the L4 on the table. I picked it up several times throughout that hour or so and it was hot. I've never touch a light that hot before. I'll be doing more tests, so I'll be able to better document the results. By the 15-min mark, it was almost to hot to hold. The good thing about this is if it ever comes on in you're pocket, you'll now about it pretty much right away.

You know, one question I keep having in the back of my mind is, if it gets this hot, then what does that say about the ACTUAL temperature AT the LS...

I wonder how well heat is actually being dissipated from the actual body of the L4 itself, since it seems like the aluminum body could barely keep up with the heat generated/transferred. That, or it's drawing heat from the LS very efficiently, but it's not dissipating it into air quick enough...

And these are low life luxeons as it is. Heat not only decreases output according to Lumiled's graphs (since this is regulated, it would decrease runtime instead), its sure to reduce the led's lifespan.

People keep talking about how if the light is getting hot, then that means the heatsink is working well. Of course, but it also means that the luxeon is HOT!!

If its too hot is the question that needs to be asked...

You guys sure that SureFire doesn't specify a duty cycle in their manual? /ubbthreads/images/graemlins/wink.gif


Mark

Well, SF did recommend that the light NOT be run continuously...

In an attempt to answer Nascar's second question, as I understand it -- "In the A2, does one battery get more depleted than the other?"

A2 burn

I put 2 fresh cells in my A2, turned it on, and laid it down. At 46:45 the light suddenly dimmed to the point that the xenon bulb was not much brighter than the 3 LEDs. I let it continue to run until 48:12, at which point it was about equal in brightness to a Arc LSHP, and at that point I turned it off.

I let it cool for half an hour and relit it. It burned brightly for 50 seconds and again dropped out of regulation. I turned it off after 70 seconds into the second run, at which time it was about as bright as my Arc LSHP.

Rear cell

Nine hours later, I removed the rear 123 cell, put it in my Arc LSHP and turned it on. The Arc was bright. I became otherwise occupied but noticed it was dimmer at about 20 minutes. I watched it get dimmer until it was about equal to my Arc AAA at 22 minutes.

Front Cell

Then I removed the front 123 and inserted into the Arc LSHP and repeated the test. This time I saw the LSHP flip from sun to moon mode at 17 minutes. I waited until the brightness decreased to the level of my Arc AAA. It was at 22 minutes.

Conclusions

Ouch! That does not support the theory that the front cell will become more spent in the A2. But it does not disprove it either. The test was not precise enough. I didn't use a light meter. But I do have some conclusions:

1. If the batteries in the A2 are used up to different extents, the difference is not much.

2. The A2 does not deplete the 123 cells. The Arc LSHP, which has a life of about 120 minutes, was able to suck 22 minutes out of each battery. Perhaps we can say that the A2 used only 5/6 of the 123s?

Paul

[ QUOTE ]
GreenArcher said:
Is it a lot warmer/hotter than the SF E2E after 30 minutes?

[/ QUOTE ]
That is a resounding YUP! I don't currently have anything that gets quite as hot as my L4. The E2 gets warm. The L4 gets HOT.

[ QUOTE ]
PaulW said:
... The Arc LSHP, which has a life of about 120 minutes...

[/ QUOTE ]

I measured 5 hours regulated on 2AA lithiums

Brightnorm

Thanks Paul Very useful information.

One important point to keep in mind is that resting the batteries sometimes gives them a bit more life. An important difference between this_is_nascar's test and PaulW's test is that PaulW gave the batteries a long break before putting them in the Arc LSH. From this_is_nascar's description it doesn't sound like he included a similar pause. This may account for some (but probably not all) of the difference between the two tests.

I suspect that the L4 really is better at draining the batteries since it uses a boost circuit which the A2 (as far as I know) does not. We have reports that the KL4 lights up with as little as 3V so in a 2-cell configuration it can probably drain them down to half their original voltage, while I doubt the A2 can go anywhere near that low and still light up.

That said, these are interesting tests; thanks for doing them!

- Russ