Streamlight 4AA LED--I'm confused

[JustAGuy]

Streamlight 4AA LED--I\'m confused

I've read some good things about the SL 4AA 7-LEDs, and am seriously thinking about buying one. But after doing a search here, I've got two questions. First, I've read that the run-time (with the LED version) is anywhere from about four to 150 hours; I'm obviously missing something here. Which figure is correct? Second, there were a number of comments about the LEDs being overdriven. What does that mean for an LED? Does it just mean it will only last 5000 hours instead of 100,000 hours, or that it will also make a nice pocket warmer, or what?

Thanks in advance for any help!

 

[Deleted member 684]

Re: Streamlight 4AA LED--I\'m confused

4 hours of bright diminishing light followed by 100 ++ hours of dim diminishing light.

The LEDs are heavily overdriven. Yea, that means they will last 5 years > of continuous use. But you ain't got a battery to last you 5 years do you? Even if you use them 3-6 hours a day, they are good for 10 years by which you would have changed your light.

 

[StevieRay]

Re: Streamlight 4AA LED--I\'m confused

Regardless of how long the LED lasts, Streamlight offers a lifetime warranty to repair or replace!
I own this light and really like it.

 

[JohnK]

Re: Streamlight 4AA LED--I\'m confused

Streamlight has a refreshingly honest graph on the back of the bubble pack showing the drop in brightness over 156 hours. I wish other manufacturers did this. I haven't run mine enough to dim it, but I am REALLY pleased with this light.

 

[StuU]

Re: Streamlight 4AA LED--I\'m confused

Put a dummy cell in the SL7 4AA. It will cure the massive over-heating of the head and will give a much longer run time.......and, still, plenty of bright, useful, light.These leds are not designed to endure 90ma/led.

 

[INRETECH]

Re: Streamlight 4AA LED--I\'m confused

There are a lot of companies out there producing flashlights using the T1-3/4 (5mm) LED; which is only designed for 30-50ma; and they are running it at almost twice that much

The problem with that package is that the LED-die simply can't transfer the wasted heat energy out of the package; by running the current higher than specified - sure, you will get a lot of light, but you are causing damage to the LED

 

[cmassicotte]

Re: Streamlight 4AA LED--I\'m confused

Quoting INRETECH -- "The problem with that package is that the LED-die simply can't transfer the wasted heat energy out of the package; by running the current higher than specified - sure, you will get a lot of light, but you are causing damage to the LED"

Quoting NERD -- "The LEDs are heavily overdriven. Yea, that means they will last 5 years > of continuous use. But you ain't got a battery to last you 5 years do you? Even if you use them 3-6 hours a day, they are good for 10 years by which you would have changed your light."

QUESTION: Even if Nerd is only close in his estimate of the real life of the LED, is damage to the LED a significant issue? Particularly given the Streamlight warrantee?

Does "damage to the LED" affect performance over the actual lifetime of the LED? Or perhaps I should ask "How does damage to the LED affect performance over the lifetime of the LED?

Chuck

 

[Wits' End]

Re: Streamlight 4AA LED--I\'m confused

The over driving to my understanding(quite likely faulty

)will cause the led's to--
Will get dimmer after a period of time.
Will not live their 100,000 hrs.
will get warm (w/ only 7 5mm leds not a big factor)

But all that said Streamlight does have a good rep w/ it's warranty and will replace it even after 100,000 hours of use, assuming you are alive

 

[McGizmo]

Re: Streamlight 4AA LED--I\'m confused

cmassicotte,

The LED life is actually a half life. The 100,000 hours quoted on Nichia is a best case and implies that after 100,000 hours, the LED will put out half the luminous output that it did at the start. The LED's actually start dimming much earlier in the time frame. I don't know what LED's Inretech is referring to when he states 30 to 50 mA of current. The Nichia's which are the white LED's used by most have a max rating of 30 mA and suggested target current of 20 mA!

Both temperature and current are the degrading element here. If the LED's are really running at 90 mA, I would expect that one could empirically test the luminous output with a new light and confirm degradation well within the actual usefull life of the light. For an idea of the relation between heat and luminous output over time, take a look at this PDF:

presumption-of-life-time.pdf

Notice that there are two curves provided; one is at 10 mA and the other at 20 mA. I don't know if Nichia has some projections on higher currents but I believe they do. As I recall, I once asked a Nichia rep about the life of an overdriven LED and was given an estimated half life of 500 hours. Unfortunately, I can't remember the hypothetical current in this example.

From the graph, at 60 degrees C, a 10 mA LED will have a half life of 15,000 hours and a LED run at 20 mA will have a half life of about 7000 hours. One can only guess at the half life of a LED run at 90 mA with an ambient of 60 C!

Realistically and with short runs of the light where the temperatures don't climb so high, it is possible that the typical user won't notice the degradation of the LED. I do find it somewhat humorous that there was such an outcry about the 5 W Luxeon being down rated to 500 hours and then back to 1000 hours for its half life. It may well be that manyof the other LED lights on the market are driving the 5 mm's at a rate that could bring the half life below that of the 5W Luxeon. It is clear from Nichia's graphs that not only temperature but the current itself effects the half life of the LED. Thermal management alone doesn't guarantee longevity for the Nichias and I suspect that this is the case for the Luxeons as well!

- Don

 

[LoneRebel]

Re: Streamlight 4AA LED--I\'m confused

On a replacement 4aa 7 LED that I recieved, there was an additional 1 ohm resistor soldered on to the base of the LED assembly head. It looked very much like a hack job and I imagine it is due to too many lights being returned and streamlight is correcting their mistake.

Still is a nice light though..But I'm stuck on luxeon stars now.

 

[BuddTX]

Re: Streamlight 4AA LED--I\'m confused

As others have said:

It's a nice light, at an affordable price, made by a big, reputable company. So what if it is overdriven? (who here doesn't want a brighter light?) If it ever breaks, send it back to Streamlight. They will be here tomorrow!

FWIW, Size aside, I prefer the 3C to the 4AA. However, if pocketability is a concern, the 4aa is a winner.

Like the package says, it can go UP TO 155 hours on a set of batteries, with diminishing brightness. So use it for 10-20 hours, and replace the 4aa batteries. Wal-mart sells a Rayovac 8 pack of AA batteies for 3.97. That's 2 dollars per set of batteries.

The nice thing is that you do not HAVE to change the batteries at that time, unlike other flashlights that will become nothing more than a glowing tip.

 

[rlhess]

Re: Streamlight 4AA LED--I\'m confused

I have a runtime graph on my Website (see sig)...for the first few hours of run time. This is the early model w/o the extra 2.0 ohm resistor in series.

Cheers,

Richard

 

[haertig]

Re: Streamlight 4AA LED--I\'m confused

Originally posted by JustAGuy:
First, I've read that the run-time (with the LED version) is anywhere from about four to 150 hours; I'm obviously missing something here. Which figure is correct?

<font size="2" face="Verdana, Arial">I's had one of these for a few months. My batteries did not last long. Intermittant use, maybe 2-3 minutes max each use, every few days. I'd guess anout 1 hour total use. I found a significant dimming. Not slowly over time. But one time when I turned it on I said to myself, wow, this is pretty dim. It was several times dimmer than my Arc AAA that's been on the same battery for over a year (same intermittant type use). Fresh batteries brought the Streamlight back up to it's normal bright self.

I'm hoping that I just had a bad battery in my first batch (all were new Energizers). Nobody else in my family claims to have used the light for more than five minutes total since I got it. We'll see if the new batteries (Duracells) perform better. I have a hunch (a hope, actually) that a simple bad battery might be the cause. I had my Infinity suddenly expire on me out of the blue a few months back. Same "no slow dimming" scenerio as the Streamlight. It was good one day and bad the next. I'm pretty sure that it's Energizer came from the same batch as those in the Streamlight.

 

[Owen]

Re: Streamlight 4AA LED--I\'m confused

I hope those were bad batteries, and not a problem with the light. I've used my AA7 for several hours without an appreciable drop in brightness, including more than an hour's use in one day.
I just got back from a few days in the woods, and one of my buddies that I gave a SL4AA7LED used his constantly over the course of two nights(after discovering that it works with one of those headbands for the Mini-Mag with a velcro strap). It gets dark around 5pm, and we stayed up til around 9 or 10. It wasn't running the entire time, but he kept it on for cooking, eating, gathering firewood, etc, etc, and it's still going strong after several hours use. He loves it.
A real happy camper...lame, I know

 

[doubleganger]

Re: Streamlight 4AA LED--I\'m confused

Edit: I found the answers in other topics

 

[Tech a Billy]

Re: Streamlight 4AA LED--I\'m confused

I noticed that one of the seven LED's on my SL4AA was not working after less than an hours use. I called Streamlight on Monday and had a new lamp module in my mail on Friday. The new module looks identical to the original except for a whiter or less blue color, no additional resistor that I could see. OK, I'm happy again. Thanks Streamlight.