LED Long Runtimes?

[UnknownVT]

Getting 5 hours at good brightness from a single AAA alkaline cell sounds pretty good (eg: the 2002 Lummies winner the ArcAAA)

11 hours with a single AA cell on the CMG Ultra could be said to be "better"....

One of the major attractions with LED lights is that they give "enough brightness" with very long runtimes.

5 hours and 11 hours - certainly sounds "long" compared to regular incandecent flashlights -

- but is it - really?

how about the pretty dim CMG Infinity (regular) at an advertized 41 hours? That's beginning to sound "long".

However one of the reasons I initially purchased a Photon yellow - was because of the reputed/advertized compromise color of yellow being good for definition and somewhat preserving "night vision"** -

BUT the major attraction was its spec'd/claimed/advertized long runtime -

How long?

Try 120 hours !!

I have not been able to test to confirm this claim but my original Photon I yellow has been on my keyring since I first got it years ago - and it is still acceptably bright - and bright enough for most close/personal purposes.

The Photon 2 and Photon 3 in red, orange and yellow all use a single 2032 cell but are all spec'd at 120 hours.

http://www.photonlight.com/more_info/tech_specs.html

So are these claimed runtimes true?

How is this achieved?

So why aren't there more LED lights that approach these kind of runtimes?

--------------------------------------------------
re: ** "night vision" and colors - see the thread posted recently on cpf:
Preserving Night Vision - Colors?

 

[Roy]

duplicate posting

 

[r2]

LRI's advertised runtimes are not very accurate from what I understand. I had a couple Photon IIIs (the 2x2016 colors) which dimmed very quickly. They were almost useless after maybe a couple hours of total runtime (they advertise 10-12).

I don't know about the yellow, red, and orange, but I suspect the exageration is similar. It will dim pretty steadily and be mostly useless after 10 or 20 hours (I'm guessing here).

If you want a really dim light, you can get some great runtimes. Those lithium coin cells have very low capacity, though, so a long runtime necessarily means a dim light.

- Russ

 

[Roy]

The reason for outlandish claimed runtimes is that there is no recognised standard for "minimum acceptable amount of light". On my runtime plots I generally use the standard of being able to see my feet as the acceptable minimum level of light generated by a flashlight. You could just as easily use the ability to see a keyhole from three inches as a minimum standard. One standard used is the minimum amount of light needed to read a news paper. Sadly, most package advertising does not quote the standard being used in stating runtime.

 

[LED_ASAP]

The point is Brightness vs. run time. For a given battery, the lower the current draw, the dimmer your light go, and the longer it lasts. A modern LED will start giving out light with a few micro Amps (no, it's not a typo, it is 1/1000th of a miliAmp), and you will get enough light to see the key hole or watch face or other small needs with less than one miliAmp. At 5-10mA it's already bright enough to walk around with in total darkness...

If you need to have a flashlight that will last hundreds of hours, you just lower the current draw---but don't expect them to be blindingly bright.

If you are interested, you can refer to my earlier post in the home-made/mod forum and use a 50-100K resistor instead of 1K, then you get a Solitaire mod that draws less than 1mA and can last for 500+ hours on a single AAA alkaline.

 

[Bmccue1964]

My definition of adequate brightness:

Lighting my way down a mountain in total darkness (no moon) so that I will not fall off a cliff or run into a tree.

 

[dangee]

120 hours - 119 hours 59 min = 1 min. the time it took me to realize i should buy another arc aaa instead. (and i did that math in my head)

 

[UnknownVT]

The old Photon I yellow I have on my keyring is definitely bright enough for me to read a map by (one of my prime uses) - it is bright enough to walk by - so yes I can see my feet clearly with the light. So to me this is usable/practical/enough brightness

However I supect despite its apparent "antiquity" - it may not have had enormous hours of usage - since it is a mk.1 with squeeze-on only.

However the fact that it has lasted for that many years on my keyring and does get used regularly - seems to me to have "lasted"....

Roy have you ever done your runtime test with a Photon II (or 3 at full brightness) in the claimed 120hours - red, orange, or yellow?

I'll check out the Solitaire mod - sounds real interesting..........

Many thanks for the inputs so far.

 

[Lurker]

Those Photon claims are pretty amazing. One of the flashlight review sites has a pretty good output graph that, IIRC, confirms the claimed run-time for the white Photon (12 hours), but illustrates that the output falls off considerably over that time. I remember thinking that only about the first 1/10th of the claimed run-time was really meaningful. I can't remember if I was allowing for at least 2/3 of original brightness or 1/2 of original brightness.

If that same 1/10 fraction extrapolates to the Yellow Photons, you can figure about 12 hours of pretty good brightness. 12 hours is great run-time from any light, especially one that small.

Here's something to consider: Based on the same graph and extrapolation, I estimate that one of the 1 x 2032 Photon 3s set to the lowest brightness setting may put out a fairly steady level of light for 240 hours. And that's actually enough brightness to find your way around in a dark house (barely) or do many close-range tasks.

 

[webley445]

Try 380+ hours! I wired two leds in series with a 270 ohn resistor to a 9v alk and left it running. Took about 3 days of continuous running to see noticeable dim. Seemed to hang at that point 3-4 more days then slowly went down hill from there. Thats over two weeks of continuous run. the last 5-6 days was very dim, but still able to see your feet [dim, not bright] and able to read the letering on a tooth paste tube @ 3".

So if a switch was utilized and only intermitten use of the light, geez it would last seemingly forever.

Made a few of these little toys up and will be keeping them for emergency backups. Imagine being without power in your home for 3-4 days, these babies would help you through it. looking to post them on my humble little web site soon. I'll post a link here when it up.

BTW, light was placed in my bathroom during testing, and light output, though measured without the aide of any equipment, was done by "eye" in the dark with door closed, usually at night.

All this brings to mind some thoughts I have been having about the perception of "brightness" in comparing incans, leds, and candles. Have some personal observations about what "seems" to be bright, but ambient conditions seem to affect our perception. maybe I'll do a post here about my thoughts when I have time to ramble out a long rant.

 

[INRETECH]

its very easy to get incredibly long run times with LEDs, just increase the resistor - and you can have one that lasts for months, maybe even years; but what good is having a light that is very dim ?

You have to decide what is the min acceptable amount of light that is usable ?

At what point is the light too dim to be useable ?

Brightness X Operating_time = Weight

 

[radellaf]

My favorite really long runtime LED light is the Eternalite X-Ray. The dim blue LED "NightBeacon" I've had running since I got it, more than 6 mos. ago, and it's a nice bedside table nightlight. Just enough to see where it is in the dark initially, but getting up in the middle of the night, my eyes have adjusted to where I can kinda see what's in the room enough to not stub my toe.

 

[Quickbeam]

Generally when reading manufacturer's claims about LED runtimes, I'll invoke "Doug's Law of LED Illumination"

which states that:

"In general, you should take the battery life claimed by the LED flashlight manufacturer and divide by 3. This is how long the LED(s) will probably produce light before you will want to change the batteries."

Notable exceptions would be the Arc AAA and others using boost/regulator circuits.

BTW, the fact that the infinity ultra has double the runtime as the Arc AAA, with about the same output makes since, as a AA battery has double the capacity of a AAA battery.

 

[UnknownVT]

Originally posted by INRETECH:
You have to decide what is the min acceptable amount of light that is usable ?

<font size="2" face="Verdana, Arial">Good practical post, thanks.

I guess that's why the Photon microlights are so popular - they manage to to give an acceptable/useful level of brightness for mostly pretty good runtimes - and in the case of their red, orange and yellow - a claim of an incredible 120 hours battery life.

For example I have a yellow Photon II which I picked out of 6 (for gifts)- that's visibly brighter than the yellow Photon 1 on my keyring.

But is that additional brightness of any practical use? To me, probably not - that's why the old worn Photon 1 yellow is still on my keyring as my un-noticed EDC.

I can read a map with it in the car - (yes, it does lose the populous areas - but most people would recognize those anyway) the definition is high and yellow causes less glare. It seems to disturb my dark adaption less.

Yet it is definitely bright enough to see one's feet/shoes, and bright enough to walk by for dark conditions when it would be uncomfortable to walk without a light.

So that years old worn yellow Photon 1 is what I call "bright enough" - and it is spec'd at 120 hours battery life - I know probably not at full brighness - but it is still working fine for me.

 

[EMPOWERTORCH]

Its just amazing how much run time you can get out of 3 cheap D cells in a 2 cyan LED torch!
The torch bulb was originally created in the spring and was first used in a Benross 4033.
This was taken on as couple of camping expeditions where it was often left burning all night.
The bulb nd batteries were then transferred to a 3D aluminium torch similar to a maglite. The torch was used as EDC for several months, and was my only light source during my 3 week camping holiday in he USA this September, where it was used to light up everything from the dining area to long night walks by the lake. The torch was also my bedside light. Several nights the torch has been imnadvertantly left switched on, and it would still be found burning away brightly the next morning! I oftemn read at night and fall asleep reading...!
It has spent many hours providing a serene cyan glow in my bathroom when the bulb blew!
Thee output is more green now, but the light is still useable. The batteries cost me a sum total of 75p! I've had a lot of light for 75p!

 

[ikendu]

Originally posted by r2:
LRI's advertised runtimes are not very accurate from what I understand. I had a couple Photon IIIs (the 2x2016 colors) which dimmed very quickly. They were almost useless after maybe a couple hours of total runtime (they advertise 10-12).

<font size="2" face="Verdana, Arial">If you look here, Brock's runtime chart, you'll see that the P3 starts at 19 but drops to 13 after 15 minutes and stays at 8 or more for 10 hours.

So...I guess much depends on whether you think that "8" relative brightness is "almost useless". The discharge curve is actually fairly flat for an unregulated light.

 

[MY]

I have an eternalight hanging in my bathroom right next to the toilet. I have the setting on the lowest position and leave it running 24 hours a day. This amount of light is just right when I need to answer nature's call in the middle of the night and not have to worry about missing the hole. I usually change batteries once every 2-3 months.

 

[FalconFX]

1100+ hours on the Eternalight's lowest setting with lithium AAs will beat 120 hours of Photon lithiums anytime... A month and a half of straight, continuous usable light is well worth it.

 

[UnknownVT]

Originally posted by FalconFX:
1100+ hours on the Eternalight's lowest setting with lithium AAs will beat 120 hours of Photon lithiums anytime... A month and a half of straight, continuous usable light is well worth it.

<font size="2" face="Verdana, Arial">--
Very impressive....

so how does the EternaLight feel on your keyring?

size matters

I do understand and appreciate the ability to leave a light on 24 by 7 -

but I haven't had the need for that -
I can reach a flashlight on my keyring, or by my bedside, and use it when necessary -

then something like the resoundingly beaten Photon yellow at a mere 120 hours seems to just last "forever"......
whereas a light the size of an Eternalight would not fit as conveniently where a Photon would -

besides I really don't need it to be on while riding in my pocket

 

[FalconFX]

Actually, before I came across the Arc and CMG, the Eternalight was always carried in my jean pockets. Although it won't carry on a keychain, it can stand upright at night on end and light up a room as well as a candle can. A light that can last 5 years on intermittent use with the same original lithiums can't be beat.

Photons are meant solely as keychain lights, and under that limitation, it's purpose can't be compared to something like an Eternalight. Of course, the runtime CAN be compared, and here, just about nothing beats an Eternalight.

Also, whereas the Photons can operate at a reduced output, Arc and CMG have no such option (unlike an Eternalight). Otherwise, chip-controlled output reduction can very well push something like Arc or CMG to well beyond 100 hours of light. Plus, whereas some manufacturers intend to have their products last longer on a battery, some prefer to have the maximum light output, yet still desireable runtime. Hence, a compromise: CMG or Arc.

Plus, whereas the technically savvy can easily replace their batteries for a Photon, I've come across more than enough people who assume that after the battery is toast, so is the whole light. Their excuse for at least not making a concerted effort to replace the batt? It looks and feels cheap...

You have things such as an Arc LE or a CMG Ultra, which sacrafices runtime for brightness. Then you have things like the LED-Lenser, which, in a pen-style light, lasts 200 hours on N cells. Or a Photon III, at 120 hours on a keychain. It depends on what you want that light to be used as versus how long you want it to last and how bright you want it to be.

"Chaq`un a son gout..."