Fenix Rebels and heat

[Mr. Blue]

Been away for awhile but have heard that the rebels could be da bomb...in small lights like the L1 and LOD, is there enough heat sinking to accomodate the extra heat generated? I mean I love my LODQ2, but the rebel 80 looks pretty sweet. I would jump on it if the sinking is there...is the jury back yet on how well these are sinked? I don't want to fry the light while using it on medium or high continuously when I am in the middle of the Adirondacks...

 

[flashy bazook]

I too am interested in the Rebel version of the L0D. There is also one with the Rebel 100 (but not available in the US as yet).

Probably makes sense given the possible problems you mention to wait for people to buy first and provide reviews (output, runtime, heat issues, etc.) before you jump in.

It sounds like you are in no hurry, since you already have an L0D Q2!

 

[matthewdanger]

I may be wrong... but since the Rebel is essentially twice as efficient as the Luxeons that it is replacing in the L1T, I think that no more heat is produced than the Luxeon version. It creates more light at the same drive levels, not more heat. Again, I reserve the right to be wrong.

My point is that if the older Lux models have held up just fine, the newer Rebel models should as well.

 

[wild68fury]

My P3D RB100 runs cooler than my P1D CE.

 

[Gunner12]

The Rebel is more efficient then the Luxeons used in the previous lights so more of the energy is used as light and less is used to produce waste heat. Since the Luxeon versions didn't fry, I'd expect the Rebel versions to have an even lesser chance of frying due to heat.

 

[moon lander]

i asked the question a while ago and the answer i got was: when upgrading leds to a better flux bin, at the same drive level there should be more light, the same runtime, and the same (or even a little less) heat
i also heard something about the rebels making alot of heat, could it be that they are actually being driven harder than a cree would be in the same light due the the rebels lower vf?

 

[MattK]

My P3D RB100 runs cooler than my P1D CE.

Apples and oranges in terms of thermal area.

 

[Mr. Blue]

ya think the rebel 80 is worth it over the LODQ2?

 

[jrv]

The Rebel is more efficient then the Luxeons used in the previous lights so more of the energy is used as light and less is used to produce waste heat. Since the Luxeon versions didn't fry, I'd expect the Rebel versions to have an even lesser chance of frying due to heat.

This assumes that the Rebel can withstand the same heat that earlier emitters could handle. In other words, even if a Rebel runs a few degrees color it might have a much lower tolerance for heat to start with. I don't know if this is the case.

 

[Gunner12]

This assumes that the Rebel can withstand the same heat that earlier emitters could handle. In other words, even if a Rebel runs a few degrees color it might have a much lower tolerance for heat to start with. I don't know if this is the case.

You've got a point, and the Rebel has a smaller area then a Cree so the heat is also more concentrated. But Fenix uses thermal compound to transfer heat from the LED to the heatsink and the heat then goes to the body so if the heat can be transfered efficiently, there shouldn't be a problem with overheating the LED.

 

[L.E.D.]

Regarding heat and the Rebel, it all boils down to what mechanism it uses for handling thermal expansion to avoid failures like breaking the bond wires. I know that Cree uses a glass dome floating on liquid encapsulant, and the dome is surrounded by the little metal ring, it can rise and sink to accomodate for thermal expansion. The SCC LEDs seem to use flexible domes which can flex with the expansion (speculation). For the Rebel, I have no idea what mechanism it uses, or if it even uses one at all. It looks like hard plastic just bonded right to the little die, but who knows? As far as phosphor and die stability / lumen maintenance, all of the major players seem to be using good stable materials.

The performance and output of the Rebel are very nice, so it will be interesting to see if someone knows exactly what its thermal coping mechanism is...

 

[shakeylegs]

ya think the rebel 80 is worth it over the LODQ2?

Just reveived two of the LOD Reb100's with OP reflectors. I have not done extensive runtime tests but under normal usage they are no warmer than the LOD Q2. On alkalines, the rebels are significantly brighter and outthrow the Q2 (smooth reflector). On e2's, the reb100's put out a lot of light. Spot brightness is almost equal to the Q2 spot and the spill is significantly smoother and brighter.
Some beam shots here:
http://www.candlepowerforums.com/vb/showthread.php?p=2132830#post2132830

 

[Luminescent]

This assumes that the Rebel can withstand the same heat that earlier emitters could handle. In other words, even if a Rebel runs a few degrees color it might have a much lower tolerance for heat to start with. I don't know if this is the case.

Rebel is actually MORE heat resistant, while producing LESS heat for the same output due to it's higher efficiency.

The Rebels are MORE efficient than earlier LEDs [100 Lumens/watt for a Rebel-100], so they will produce less heat for the same light output, but because they can actually handle MORE heat [junction temperatures up to 150 degrees C], some companies are heavily overdriving them. The Rebel is small, but once properly mounted, it is one tough little sucker, that can actually take a lot of abuse, and this has lead Fenix to push the Rebel to almost 200 lumens in some of their lights and it is these highly overdriven situations that has caused the false impression that the rebel runs hot.

The Rebels are indeed much more efficient than earlier Luxeon LEDs in fact the Rebel 100 is easily on a par with a CREE Q2 and it's lower Vf seems to make it work a bit better with many of the Fenix lights making it even better in these lights than than a Q4 or even Q5 CREE.

The more concentrated heat with the smaller thermal pad on the Rebel is NOT and issue for professional applications, because the thermal resistance of the soldered attachment point is very low. It IS a problem for 'Modders' who just want to jam the LED emitter into a bubble-gum sized blob of thermal epoxy, because thermal epoxy doesn't give enough thermal conductivity with the smaller rebel pad.

So the Rebel needs to be soldered to it's mount, but soldering the thermal pad of the Rebel to a heatsink is something best left to the pros, because failure to closely follow the exact thermal profile required can kill the device outright or lead to unreliable operation later.

This is no different than a lot of other surface mount devices, and just like every other brand of LED out there, the Rebel will be widely available PRE-MOUNTED on various sized star-board mounts, and these mounts, because of thier larger contact area, can be attached to the lights heatsink with thermal epoxy or just screwed down with thermal grease just like other types of emitters.

So 'Modders' should stay with Rebels that are pre mounted on star boards.

The issue about CREE's having floating lenses to protect the bond wires etc, is bogus, the rebels don't even HAVE 'bond wires' to fail.

I do have to admit that for applications that are not too cramped, I like the larger CREE package, it's just easier to handle, and the lens is a tougher and less easily damaged, but once the emitter is safely encased in a light the little rebel should be at least as rugged and shock resistant as the CREE (and maybe more shock resistant due to it's very low mass and lack of bond wires).

So to recap:

Rebel is actually MORE heat resistant, while producing LESS heat for the same output due to it's higher efficiency.

The Rebel is small, but once properly mounted, is one tough little sucker.

A few important concluding remarks:

Although the Rebel is a strong contender, to get the full benefits you need to stay with the higher bin full spec Rebel-100 device.

Rebel-100 has as high or higher light output as just about anything out there, but this is NOT true of the Rebel-80, Rebel-50 etc.

So DON'T let Fenix fob a Rebel-80 off on you. The Rebel-80 must now be considered a SUB-SPEC device suitable only for very low-end applications.

DX is selling five mode MTE Rebel-100 lights for 18 dollars, but Fenix would have us believe that the Rebel-100 should only be available in "Premium" lights even though their standard lights already cost Three times what the MTE light does [and even though the Rebel-100 bin emitters only cost about 2 bucks more than Rebel-80 bin emitters].

How stupid do they think we are?

 

[Gunner12]

...DX is selling five mode MTE Rebel-100 lights for 18 dollars, but Fenix would have us believe that the Rebel-100 should only be available in "Premium" lights even though their standard lights already cost Three times what the MTE light does [and even though the Rebel-100 bin emitters only cost about 2 bucks more than Rebel-80 bin emitters].

How stupid do they think we are?

Remenber that MTE might have copied some things from Fenix or other companies thus saving on R&D and they also lack the HA III, aluminum reflector, AR coated window/lens, and efficiency of Fenix's circuits. Don't forget, as things get more expensive, their performance increases less and less. The MTE is a good light for the price but still not up to Fenix standards.

Both are good lights but they were developed differently and use different quality material.

 

[L.E.D.]

The issue about Crees having floating lenses to protect the bond wires is not bogus, because it really does protect the wires lol. The Rebel may not have bond wires, but it still has a die to break, but breaking dies and / or bond wires from expansion is highly unlikely unless the light has really horrible heatsinking and is greatly overdriven. Also wether or not the Rebel even has an expansion coping mechanism (like the floating lens) is still unknown.

 

[ns66]

energy won't just disappear
that means more light=less heat and vice versa

 

[Luminescent]

Remenber that MTE might have copied some things from Fenix or other companies thus saving on R&D and they also lack the HA III, aluminum reflector, AR coated window/lens, and efficiency of Fenix's circuits. Don't forget, as things get more expensive, their performance increases less and less. The MTE is a good light for the price but still not up to Fenix standards.

Both are good lights but they were developed differently and use different quality material.

Did someone from Fenix sneak into your house and put a suspicious looking pod under you bed?

There is this myth [at least among Fenix groupies] that Fenix invented the Flashlight some time around 3000 BC in ancient China, and has been responsible for every innovation since.

Garbage, the Chinese may have invented writing, paper, gunpowder, the clock, etc, but I think it's safe to say that they didn't invent the flashlight, and it's just as safe to say that Fenix was NOT the first to incorporate a whole list of features (like MCU controlled multi-mode functions, orange-peel textured reflectors, forward clicky switches etc).

Considering this fact, by your logic, because they were able to 'copy' these ideas from others like Jetbeam, a Fenix L1D should cost HALF what a Jetbeam C-LE costs instead of more than twice as much, right?

So you see you have the right idea, it's just being applied in the WRONG direction.

Nor has Fenix been more than marginally responsive in incorporating new features, even when others 'light the way' for them [pun intended]. I joked in another thread that the U.S. went to the moon in less time than it took Fenix to figure out how to knock some frigin dents in their reflectors, and that's not much of an exaggeration, considering how long that Fenix has been in business, and the fact that some of their models STILL don't offer orange peel textured reflectors as an option.

Lord only knows when they will master the complex intricacies of the inscrutable 'Forward Clicky' and offer that as an option on more than an 'experimental' basis on one or two models.

In my view, Fenix's main virtues are that they make reasonably good lights, at reasonably good prices, with reasonably competitive features, this is enough, don't try to turn them into the Photon Gods off the Universe.

 

[Luminescent]

The issue about Crees having floating lenses to protect the bond wires is not bogus, because it really does protect the wires lol. The Rebel may not have bond wires, but it still has a die to break, but breaking dies and / or bond wires from expansion is highly unlikely unless the light has really horrible heatsinking and is greatly overdriven. Also wether or not the Rebel even has an expansion coping mechanism (like the floating lens) is still unknown.

When cited, [as it has been ad nauseam] as providing superior protection to prevent bond wire breakage, it is a bogus argument.

You can't break bond wires that AREN'T THERE.


With apologies to Hughes Mearns -

As I was giving them a stare,
I noticed the Rebel's bond wire wasn't there!
It wasn't there again today.
I wish this lame argument would go away!


The Rebels use a soft elastomeric silicone lens like the Seoul SSC P4, you can knock the lens right off if you bang on it, but unlike the SSC part there don't seem to be any bond wires to break and some Rebels have been known to keep operating even without the lens (at least on the high power white Rebel-100's).

Can't be good for them though.

 

[Jayman]

The Rebels use a soft elastomeric silicone lens like the Seoul SSC P4, you can knock the lens right off if you bang on it, but unlike the SSC part there don't seem to be any bond wires to break and some Rebels have been known to keep operating even without the lens (at least on the high power white Rebel-100's).

Can't be good for them though.

Are you saying that if I was to inadvertently drop a rebel equipped flashlight the lens might become dislodged? If this is the case then it sort of defeats the whole purpose of having these so called indestructible leds.

 

[Gunner12]

Sorry if my post angered you in any way Luminescent.

I was not trying to prove anything.

If I remember correctly, all Jetbeams use PWM but the only Fenix that uses PWM is the L0D series. I'd prefer the CL-E to a AAA Fenix because I don't mind the extra size of the CL-E. The V1.2 has a much higher PWM rate then the Fenix and is cheaper too.

I agree that Fenix is not one of the first to use multi current drivers and they are slow at getting a smooth beam. I would also love to have forward clickie on a Fenix(Hey Fenix, how about offering this as separate part like a forward LxD series clickie or a PxD series clickie).

Now that you remind me, I should check under my bed(After I get some sleep first).

About dropping a Rebel Flashlight, it'll have to be falling very fast to dislodge the LED's dome(the dome doesn't have a lot of inertia). That same fall will probably also crack or shatter the window/lens and maybe even render the electronics, battery, and flashlight useless. The chances of a small fall knocking off the dome is relatively low. But if you opened up the light up and pushed on the LED dome itself though, it shouldn't be too hard to get the dome off.