First post: Question about run times on max or turbo modes

[Kartman35]

Confused first time bright LED buyer..any input appreciated

Are any of the higher powered LEDs able to remain in Max or Turbo modes for the times listed on the package?

For example, as a non flashlight expert, looking at the specs of a Fenix PD35 (the flashlight I almost bought and might still anyway)..the specs imply that the light can produce 960 lumens for an hour. The reviews on this forum however reveal that it can only sustain that output for 3-5 minutes at a time before it goes down to 460 lumens, and can only maintain that output for another half hour or so before it goes down to 180 where it can continue to shine until the battery gives up. Is this phenomenon present in the multicell larger lights as well?

I guess what I'd like to know is how big do you have to go to get a light that can produce around 1K lumens for at least an hour at a time?

Thanks

 

[Poppy]

Hi cartman,
Yes this is a fairly common phenomenon.

I believe that you'll have to get a light with at least 2 - 18650 batteries to be able to sustain 1000 lumens for an hour.
It'll also have to be large enough to absorb, and transfer the HEAT generated by the LED.

There isn't much of a perceptible difference between a 900 lumen and 1000 lumen light. You wouldn't be able to tell the difference, unless you held one right next to the other and switched them on and off and REALLY tried to make a comparison.

Here are two reviews of lights that you might want to look at to get a feel of 1000 lumen or more, lights, and the differences of run-times at different settings, and what the beams look like.

TK35 with different emitters

Link Removed, Please see the banner at the top of the page
However links to Dealer's or Manufacturer's websites or other sellers outside of the CPF MarketPlace will NOT be permitted - Norm

Niwalker Mini max MM15 http://www.candlepowerforums.com/vb/showthread.php?385451

EDIT: Sorry Norm, I was thinking that this was the General Questions forum, not the recommend me a light forum.

Kartman,
Here is a link to a review of the TK35UE

 

[Grijon]

As you may know, the issue is heat; high power makes a lot of it and a small light simply can't dissipate it quick enough, so the light steps down to protect itself from thermal damage.

The Fenix TK41 is an 8xAA light that will run 900 lumens for nearly three hours (there's no practical difference between 900 and 1000 lumens); it's smaller than a 2xD Maglite.

 

[Grijon]

Ah ha ha, beat by Poppy! (He's one of the ones you really want to listen to on here, by the way)

And also, :welcome:

 

[thedoc007]

Armytek does make some lights that really do give you the runtime you would expect, at the rated output. I have the XP-G2 Predator, 670 lumens max, and it will run in that mode until the cell drops below a certain voltage. If you get the Predator Pro, with the advanced driver, it will literally run in max mode until the cell gives out, with no stepdowns at any point.

To the OP - I'm guessing you read selfbuilt's review of the PD35. I will point out that he uses 2200 mAh 18650s for most of his runtime tests...so you can get about 50% more runtime by using a 3400 mAh cell. (The initial turbo stepdown will be unchanged, but it will stay on high for much longer.)

I will also point out that the ANSI FL-1 standard is the main reason such claims are everywhere. ANSI defines runtime as the time it takes a light to reach ten percent of the rated output. So theoretically, a manufacturer can make a light that runs in turbo for one minute, then steps down to eleven percent of max, and holds there, and according to the standard this is perfectly legitimate. This obviously will allow for much greater runtime, and the bigger the number on the package, the easier it is to sell. Until the standard is updated, this is going to be an issue. (selfbuilt uses 50% as his cutoff, which I think is more reasonable, and eliminates the more egregious examples of misleading claims.)

And one more thing...it depends a lot on conditions. Some lights have advanced thermal regulation (Zebralight SC600 Mk II L2 is one example) and only step down as needed to prevent overheating. So in a cold climate, or holding it, or if you have airflow over the light, you may be able to get much longer runtime on turbo. That said, assuming a 3400 mAh cell, and a ~three amp current draw, it will still not last an hour at 1000 lumens. As Poppy said, you really need at least two 18650s to get that.

Yet another edit: this is not limited to smaller lights. Big lights tend to have stepdowns as well. They just have more insane turbo modes. If you want to simplify, just ignore turbo, which is by definition intended to be a short-term use mode. Look instead at high...if a light is well designed, it should be able to handle the heat from that mode for an extended period (if not indefinitely). Certain lights (the Olight SR52 is one example) don't list a turbo mode at all. This is an indication that the light is not going to have stepdowns, and that is indeed the case - it will run on high for hours.

 

[Poppy]

As you may know, the issue is heat; high power makes a lot of it and a small light simply can't dissipate it quick enough, so the light steps down to protect itself from thermal damage.

The Fenix TK41 is an 8xAA light that will run 900 lumens for nearly three hours (there's no practical difference between 900 and 1000 lumens); it's smaller than a 2xD Maglite.

LOL... I agree with Grijon :thumbsup:
EDIT: I also agree with thedoc007 :thumbsup:

 

[Wuyang]

Tk41 is a nice light. If your considering the fenix pd35 have you considered the Armtek Prime C2.

 

[Kartman35]

Yet another edit: this is not limited to smaller lights. Big lights tend to have stepdowns as well. They just have more insane turbo modes. If you want to simplify, just ignore turbo, which is by definition intended to be a short-term use mode. Look instead at high...if a light is well designed, it should be able to handle the heat from that mode for an extended period (if not indefinitely). Certain lights (the Olight SR52 is one example) don't list a turbo mode at all. This is an indication that the light is not going to have stepdowns, and that is indeed the case - it will run on high for hours.

Apparently this is not the case (At least not for the PD35). According to Selfbuilt's review, the PD35 460 lumen high mode can only go for 30 minutes before again stepping down to 180...far from the stated 3 hours.

That Armytek Predator seems like a nice option in a light that can sustain it's max power until limited by the battery and the Viking actually seems like it would go over an hour at 770 lumens with the right battery. However there are two local stores that sell some of the Fenix lights, and I'd rather pick one up in person if possible.

I'm going to compromise on the 1k 1 hour requirement a little and I'm thinking maybe the TK32? In Subwoofer's review it was still producing 600 lumens after an hour of repeatedly returning to turbo every 15 min step down. Also Bigmac reported 420ish lumens on high mode for right around 3 hours.

I figure that should be bright enough for a start and only a few more $$ than the PD35 too.

Here's a battery question...

I have ripped apart a laptop battery, so I've got 12 cells. I charged the pack in the laptop until the little light went green, and then opened it up. I have three cells that read 4.1V, five that are between 3.4 and 3.9, and 4 that are just under 1.4V. Will a charger like

FENIX ARE‑C1 18650 LI‑ION SMART BATTERY CHARGER

Link Removed, Please see the banner at the top of the page - Norm

this be relatively safe with laptop cells? I'm hoping that at least the 3 4.1V cells are good and that maybe the 5 others just didn't hit 4.1 because of the series/parallel configuration in the battery....so maybe I have 8 free batteries (or at least 3)...???Just gotta not run them all the way down or overcharge them and always wear nomex clothing right?

Thanks to all who took the time to respond to my noob questions!!