Long runtime on turbo mode?

[kinzli]

Hey all, I'm looking for a light that has a long runtime in turbo mode, and has a floodish beam, akin to my Surefire L4 that I got long ago when they first released.

I think something with an orange peel reflector would probably be good for the floodish beam.

26650 (or multiple 18650's? Single 18650 would be nice but not sure its reality) battery to support high (1200+ lumens) output for more than 20 minutes.

Enough metal around the emitter to sink that much heat.

Do we have any data to show what light(s) would support these long runtimes before heat (or otherwise) causes a cutback in output?

This is for tactical use, so I'm looking for something that can be configured for 1-click to Turbo mode and not have 15 other modes that branch off.

Thanks for any pointers.

 

[RetroTechie]

Single 18650 would be nice but not sure its reality) battery to support high (1200+ lumens) output for more than 20 minutes.

Let's do the math shall we?

Good power LEDs are up in the 120+ lumens/W range these days. But with a hard driven LED that would be a very good number already. Not to mention losses because (normally) a driver sits in between. But let's be generous and say we get 100 lm/W overall. Then 1200+ lumens means you need 12W minimum continuous power input. For say, 30 minutes that's about 6 Wh. A good 18650 has in the order of 12 Wh capacity. Also 12W @ 3.7V (nominal) is just over 3A which isn't extreme by any means. In short: single 18650 should be doable for this.

Heat: despite the efficiency of modern LEDs, technology is still at a point where most of the electric power that goes in, is lost as heat. Again let's be generous and say 1/3 is converted to light, and 2/3 is heat losses. At 12W input that's about 8W of heat (again: continuous) the LED will have to get rid of. Nothing too extreme I think but you will need good heatsinking, especially LED -> board it sits on, and that board -> shelf or pill it sits on.

To keep lm/W high I'd look at higher power LEDs like the Cree XHP50. If not for the output then for the low thermal resistance such high power LEDs offer. Since that runs on 6 or 12V you'd need 2x 18650 in series, or a boost driver. Another option is an XP-L or similar on direct drive.

In short: you're looking for a light that has very good heatsinking (for example head & shelf the LED board sits on = single piece of aluminium). Decent cooling fins on the head. Copper LED board highly recommended. If single-cell powered, most likely using a boost driver and LED(s?) from the XHP... series or similar. 1x 18650 should be doable if overall efficiency of the light is good enough.

Hope this narrows your search down a bit to find suitable options...

 

[kinzli]

Let's do the math shall we?

Good power LEDs are up in the 120+ lumens/W range these days. But with a hard driven LED that would be a very good number already. Not to mention losses because (normally) a driver sits in between. But let's be generous and say we get 100 lm/W overall. Then 1200+ lumens means you need 12W minimum continuous power input. For say, 30 minutes that's about 6 Wh. A good 18650 has in the order of 12 Wh capacity. Also 12W @ 3.7V (nominal) is just over 3A which isn't extreme by any means. In short: single 18650 should be doable for this.

Heat: despite the efficiency of modern LEDs, technology is still at a point where most of the electric power that goes in, is lost as heat. Again let's be generous and say 1/3 is converted to light, and 2/3 is heat losses. At 12W input that's about 8W of heat (again: continuous) the LED will have to get rid of. Nothing too extreme I think but you will need good heatsinking, especially LED -> board it sits on, and that board -> shelf or pill it sits on.

To keep lm/W high I'd look at higher power LEDs like the Cree XHP50. If not for the output then for the low thermal resistance such high power LEDs offer. Since that runs on 6 or 12V you'd need 2x 18650 in series, or a boost driver. Another option is an XP-L or similar on direct drive.

In short: you're looking for a light that has very good heatsinking (for example head & shelf the LED board sits on = single piece of aluminium). Decent cooling fins on the head. Copper LED board highly recommended. If single-cell powered, most likely using a boost driver and LED(s?) from the XHP... series or similar. 1x 18650 should be doable if overall efficiency of the light is good enough.

Hope this narrows your search down a bit to find suitable options...

Agreed with your assertions and so far, I'm not finding much. Even the 26650 lights have (as far as I can tell) short times until they cut back (in the order of 5 min or less) to half power or so.

So far I *think* the Armytek *might* have a driver that might not reduce power right away but I haven't been able to confirm this.

Surefire DFT Fury seems like maybe its an option but there seems to be quality issues on that one - but its a contender I think. I like Surefire beam patterns and I've had good luck with them in the past. It fits all the check boxes if the thermal regulation doesn't shut it down significantly right off the bat.

Still looking for ideas. Klarus G20 and Acebeam equivalent looked promising but even those shut down fairly quickly it seems...

 

[WalkIntoTheLight]

Agreed with your assertions and so far, I'm not finding much. Even the 26650 lights have (as far as I can tell) short times until they cut back (in the order of 5 min or less) to half power or so.

So far I *think* the Armytek *might* have a driver that might not reduce power right away but I haven't been able to confirm this.

You normally want the light to reduce power when it gets hot. And it will. I believe the Zebralight SC700d can maintain 1400 lumens "forever", but it's a 21700 light. I think it's the smallest light that is capable of doing that without getting too hot. I don't know of any small 1x18650 light that can do that, unless you turn off temperature controls.

 

[kinzli]

You normally want the light to reduce power when it gets hot. And it will. I believe the Zebralight SC700d can maintain 1400 lumens "forever", but it's a 21700 light. I think it's the smallest light that is capable of doing that without getting too hot. I don't know of any small 1x18650 light that can do that, unless you turn off temperature controls.

Yes, I was looking at the Zebralight - SC700D/FD seems to not be available anymore unfortunately. I'm ok with a larger light, was looking at Thrunite TC20NW as well as a potential candidate. Larger body with more heat sinking seems to be the need. I'm just not finding any lights that run 1500+ lumens for more than 2 or 3 minutes, regardless of (reasonable) size. Maybe I'm just not "finding".

 

[WalkIntoTheLight]

Yes, I was looking at the Zebralight - SC700D/FD seems to not be available anymore unfortunately.

Hmmm, their website says the 700Fd is in-stock, and the 700d is "Back Order". For popular lights, they are always in the "Back Order" state, but are usually shipped within a couple of weeks from when you place your order. I ordered a H600Fc a couple of weeks ago, and it shipped a couple of days ago. It's on Back Order the entire time. I think Zebralight must order a continuous supply of small batches, and are always backlogged on the popular models.

 

[kinzli]

Hmmm, their website says the 700Fd is in-stock, and the 700d is "Back Order". For popular lights, they are always in the "Back Order" state, but are usually shipped within a couple of weeks from when you place your order. I ordered a H600Fc a couple of weeks ago, and it shipped a couple of days ago. It's on Back Order the entire time. I think Zebralight must order a continuous supply of small batches, and are always backlogged on the popular models.

Right, yet no retailers seem to have the 700FD. From what I can tell though the 700's reduce output down to ~900 lumens pretty quickly, so not sure it fits the picture I'm trying to find. BLF Q8 maybe? Those seem unavailable too.

 

[WalkIntoTheLight]

Right, yet no retailers seem to have the 700FD. From what I can tell though the 700's reduce output down to ~900 lumens pretty quickly, so not sure it fits the picture I'm trying to find. BLF Q8 maybe? Those seem unavailable too.

I just order directly from Zebralight. Takes about a week to arrive from China. I think if you're in the US they ship from the US, so it's probably quicker.

From what I've heard dealers say, they don't like selling Zebralights because their margins are really low. So they probably don't stock many, if they sell them at all.

 

[kinzli]

Maybe TK35UE can do this. Seems in "High" mode it can do ~2000 lumens for the long term (30 min) before starting to drop a little...researching this one now.

 

[aginthelaw]

Features of Fenix TK35UE:

• Cree MT-G2 LED with a lifespan of 50,000 hours
• Uses four 3V CR123A batteries (Lithium) or two 18650 rechargeable batteries (Li-ion)
• Output mode / Runtime:

Turbo

1800 lumens

1h

30min

High

750 lumens

4h



Mid

250 lumens

13h

30min

Low

25 lumens

150h



Strobe

1800 lumens





SOS

250 lumens

 

[Fireclaw18]

Features of Fenix TK35UE:

• Cree MT-G2 LED with a lifespan of 50,000 hours
• Uses four 3V CR123A batteries (Lithium) or two 18650 rechargeable batteries (Li-ion)
• Output mode / Runtime:

Turbo

1800 lumens 1h 30min
...

Those numbers are misleading.

Fenix rates the runtime for turbo (and all other modes) as from when you turn it on, to when the light finally shuts off. (or for manufaturers using ANSI FL1 standard... when output drops below 10%, rounded to nearest quarter hour)

The TK35UE does NOT maintain 1800 lumens for 1 hour 30 minutes on turbo. To see what it actually does, do a Google search for Zeroair's review of the 2018 edition Fenix TK35UE. That review includes runtime output graphs showing the actual tested output.

From Zeroair's review of the 2018 edition Fenix TK35UE, the actual output curve of the TK35UE on turbo mode looks like this:

Minutes 1-10 - starts at 100% and ramps down gradually to 87%, then sharply drops to 50%.
Minutes 11-20 - Output then sharply rises back up to 80% before falling to 50% again (over 10 minutes).
Minutes 21-45 - This cycle repeats with the peak getting lower each time. The final peak is around the 45 minute mark with output at 65%.
Minutes 46-90 - Output then sharply declines with no more peaks. It levels off at 10% at around the 60 minute mark, before stairstepping down further.
Minutes 90-180 - Output is around 1% or less for the final half of the total runtime.

Note also that Zeroair did his review with external cooling (fan blowing on the light). Without external cooling output would drop even faster as the light overheated and the temperature protection kicked in.

While it may seem misleading for Fenix to say "1800 lumen turbo" with "runtime 180 minutes", this is actually pretty much industry standard for how these statistics are reported. Basically, all manufacturers report their outputs in a similar way.

 

[Stefano]

Features of Fenix TK35UE:

• Cree MT-G2 LED with a lifespan of 50,000 hours
• Uses four 3V CR123A batteries (Lithium) or two 18650 rechargeable batteries (Li-ion)
• Output mode / Runtime:

Turbo

1800 lumens

1h

30min

High

750 lumens

4h



Mid

250 lumens

13h

30min

Low

25 lumens

150h



Strobe

1800 lumens





SOS

250 lumens

I have this light (TK35 UE with led MT-G2) is very beautiful but the Turbo level 1800 lumens only lasts for 5 minutes, then drops to 750 lumens. (it has a timed timer)

TK35 2018 (3200 lumens with led XHP70) can definitely stand at 1000 lumens without limits.Perhaps even 2000 lumens, it has no timer, it has a thermal sensor that operates at 65 degrees C °
If the external ambient temperature is very low, it could also supply more than 2000 lumens for a long time.

 

[scout24]

Consistent high level with no stepdown? Possible tactical use? As simple as possible? See Malkoff or Elzetta. Don't get hung up on a specific lumen number, it takes more than a couple hundred one way or the other at that level to really see a difference.

 

[bykfixer]

The 2x 18650 Streamlight ProTac HL5 does 1000 on medium. About the size of a 2C Maglite.

The SureFire EDCL2T is crazy bright, even after it steps down.

 

[kinzli]

The 2x 18650 Streamlight ProTac HL5 does 1000 on medium. About the size of a 2C Maglite.

The SureFire EDCL2T is crazy bright, even after it steps down.

Some good suggestions - the Streamlight looks like a good option, as does the Malkoffs but they seem like unobtainium. Thanks guys!

 

[lumen aeternum]

Let's do the math shall we?

Seems like heat removal is the critical factor here?
What about using several emitters of lower power? This would make it more floody, but that's usually OK in "tactical" usage.

 

[RetroTechie]

Seems like heat removal is the critical factor here?

Indeed. Back in the day I ran a PC with passively cooled Intel Pentium (150 MHz or so) that had a roughly 5x5x5 cm cooler on it. No fan. At full speed the CPU would draw ~6W and run very hot. But its job & software configuration was such that it spent around 90% of its time in a low-power idle mode (2W), making for an average of a bit over 2W.This would run fine with the passive cooler (PC was used as a firewall / router and running 24/7 in case anyone's curious).

Keeping this in mind, I doubt the flashlight head would suffice to shed 8W. Unless it's huuuge. With body attached you have a much larger heatsink. I suspect not quite enough to keep temps reasonable on extended runs. So tailstanding for extended periods @ full power is probably out. But with the light in hand, your body also helps to carry heat away. All combined will probably do.

What about using several emitters of lower power?

That would make the LED -> LED board thermals easier. But that's not the limitation here. With copper pcb and well-constructed head + pill (hence why I recommended that), flashlight body temperature should be not much below the LED pcb or LED itself. Giving a situation like "if you can hold the flashlight & not burn your hand, LED should be okay". Obviously by the time you're pushing that limit, batteries will also be above that temperature and not be happy... :laughing:

That was kind of my point: make sure that [LED -> LED pcb -> flashlight body] thermal path is done right, then while holding the light in your hand you should be able to feel 'how things are doing'. 8W (or thereabouts) is not a lot, but "passive cooling only" is a rather tight constraint.

 

[Keitho]

"Tactical flooder", interesting combo. My SLN P60 host is a hunk of heat sinking Al that is currently holding a monster P60vn mule; it will stay on at ludicrous speed for a couple dozen minutes with some minor temp control, and gets close to reaching the end of the 21700's capacity before it is too hot to hold. With a quad flooder it would stay on turbo even longer before requiring asbestos tactical gloves.

 

[kinzli]

"Tactical flooder", interesting combo. My SLN P60 host is a hunk of heat sinking Al that is currently holding a monster P60vn mule; it will stay on at ludicrous speed for a couple dozen minutes with some minor temp control, and gets close to reaching the end of the 21700's capacity before it is too hot to hold. With a quad flooder it would stay on turbo even longer before requiring asbestos tactical gloves.

Yes, I've been talking to Vinh as the SLN looks to be a good option here as well. I'm listening and learning here guys, appreciate the conversation.

 

[kinzli]

So far I've ordered a Streamlight HL-5X and a Thrunite TN20 NW to test with and see how they do, hoping that their midrange output settings will allow ~1500 lumens or so for a longer haul.

Waiting for the Malkoff Wildcat V6 to be available and will add that in as well. I imagine that will be the best one but we'll see.