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  1. #101
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    I have received and disassembled the light.
    I am going to install it on my custom e-bike (200watt/hours 36v A123 battery, so plenty of light runtime).

    First of all, the UI (mode switching, led indicators, etc) is **spectacular**. Common cheap chinese lights are one (maybe ten..) step behind.

    Build quality and materials are also **very good**.

    There is a temperature sensor glued to the case, and it steps down to 75% at 68C measured with IR thermometer). This makes the case stay close to 70C (20C ambient temperature).
    Light intensity is modulated by low frequency pwm, but in normal usage scenarios this is not an issue.

    This light comes really cheap for one single tragic flaw: thermal dissipation.
    I cannot recommend this light to anyone that doesn't want to disassemble and try to fix it.
    Thermal contact with the case is made by 0.5 millimeters (HALF A MILLIMETER) of contact area. Cree XMLs are really though and can withstand really high die temperatures, but not at this level.

    When the case is at 60C, led dies are at 140C. Lumens produced decrease by 30+% and the leds are in immediate danger of being damaged.

    This light cannot be operated at full power.
    Now I am waiting for Cree XM-L2 80CRI neutral whites to be delivered from mouser, then I'll install them on the board and try to glue everything with arctic alumina, trying to make really thick lateral thermal paths to help heat transfer, that for sure won't be optimal but at least not this bad.

    This is the worst thermally-engineered light I ever came across. Beware of that.

    PS. sorry for SI units.

  2. #102
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    @ bozma88;

    Thanks for the review. Yes, there are thermal issues but I'm not sure that I would agree with your assessment that the lamp is not useable "as is".

    If you only run the higher modes "when needed" and aren't living in the desert you shouldn't have too many problems as long as you maintain air flow on the lamp when in use. Eventually I might try to mod mine as well. Let us know how the up-grade to XM-L2's work out. If possible if you remove the emitters, sure would be nice to have a picture of the mounting area minus the current emitters.

  3. #103
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    I've been using mine on high and haven't noticed any problems. The case does gets very warm, almost hot.

  4. #104
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    Long term reports will hopefully tell the story. Its coming on two weeks since mine shipped.

  5. #105
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    Quote Originally Posted by varider View Post
    I've been using mine on high and haven't noticed any problems. The case does gets very warm, almost hot.
    In my book that's a good thing.
    If the case would have stayed 'cold' would have been worse, much worse.


    /Håkan
    SWEDEN

  6. #106
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    Interesting thing about the F-Fire D99, the top is almost flat. Shouldn't be too hard to add a heat sink if someone felt they needed some additional cooling. One of the reasons I liked the look of the Solarstorm X2 was that it had more "fins" built into the lamp body. My bet is that it will dissipate heat better ( then the D99).

  7. #107
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    Quote Originally Posted by HakanC View Post
    In my book that's a good thing.
    If the case would have stayed 'cold' would have been worse, much worse.


    /Håkan
    SWEDEN
    I agree with that, but the fact that it gets hot outside doesn't tell the whole story about what temperature the internal pcb reaches.

    In this case, when the external container reaches 70C (scorching hot to bare hands), the internal MCPCB is at 120C, with leds at 140+C.

    This is the highest operational limit of these leds, and they cannot be safely operated at that temperature for any amount of time.

    The mcpcb is glued to the case with two small lateral drops of thermal glue. There is no direct contact bewteen mcpcb and case, all the heat is taken away by these two small drops of (low quality) glue. I am pretty sure that putting a lot of good quality thermal glue all around the perimeter of the mcpcb will lower mcpcb temperatures of at least 20 degrees. Scratching and removing internal anodization will improve thermal transfer further.

    Keep in mind that Cree recommends **DIE** temperatures < 85C to safely operate the light for long amount of times. This means a mcpcb temperature of 70C or less.

    Even operating the leds at 150C for small periods will damage them, because of all the thermal => mechanical stress induced on dies and bonding wires by huge temperature excursions.

    I am still waiting for the delivery of the new xm-l2s, when they arrive I'll do a deep photographic documentation of installation and thermal dissipation pre-post fix. These leds have a lower voltage drop so thermal dissipation should be 5% less compared to currently installed xml-s.

    Have a nice day

  8. #108
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    You're making some pretty big statements bozma88. Did you make your measurements with the light in front of a fan? How did you make your measurements? Most riders will not operate a high-powered light on high when they are not moving, precisely because they are afraid of the heat damaging the internals.

  9. #109
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    Quote Originally Posted by varider View Post
    You're making some pretty big statements bozma88. Did you make your measurements with the light in front of a fan? How did you make your measurements? Most riders will not operate a high-powered light on high when they are not moving, precisely because they are afraid of the heat damaging the internals.
    I made meaurements with an industrial grade thermocouple and an IR thermometer, without airflow.
    This doesn't matter because the problem here is not the temperature of the external case but the huge thermal resistance between mcpcb and aluminum case, that translates in a big temp. differential between case and mcpcb.

    In case of forced airflow the situation is not going to be better (this light steps down at a certain temperature so airflow is quite irrelevant). If the air is cool and strong enough to keep the case at 30C, leds wuold still be at 100C .

    This light is sensational regarding build quality and UI, but I think that
    this low price is due to this thermal flaw that renders it unreliable in the medium-long term.

    Luckily I think that surrounding the pcb with thermal glue will improve thermal transfer a lot.

    I'll provide some photos to make you realize how absurd the thermal management is.

    Meanwhile here's a quick comparation on how the contact between pcb and case SHOULD be and how it IS (actually the path isn't even lateral because there is considerable gap between the edges and the case).

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  10. #110
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    ^ Pics will be appreciated.

  11. #111
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    Boz, When I took mine apart I only noticed two wires. I'm assuming this is a series configuration (?) ...Am I wrong about that?

    Looking forward to what you do when you replace the emitters.

  12. #112
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    Quote Originally Posted by bozma88 View Post

    I'll provide some photos to make you realize how absurd the thermal management is.

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    Can you take a photo of the inside of the housing with the pcb removed? Is there no "wall" in the housing (behind the LEDs) to glue the pcb onto?

  13. #113
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    Can't you just put some thermal paste under the board and be done with it? After removing the old stuff, of course. I have some artic silver that I used for a PC-cpu-to-heatsink application. Can I use this, or do I need something different?

    Who in their right mind tests a high powered led light without some airflow. It makes all the difference in the world. Most light manufacturers even tell you not to use their lights on high when not moving. This goes all the way back to days when TurbuCat halogen lights were all the rage.

    I don't think it's right to trash the reputation of a light with testing doesn't replicate real-world use.

    This is a pretty nice light in my opinion. It has an near ideal user interface. It's small and compatible with industry standard battery connectors. It has a spot-flood combo beam that's very nice although not perfect. And it was a very good deal at $32.

  14. #114
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    Quote Originally Posted by varider View Post
    Can't you just put some thermal paste under the board and be done with it? After removing the old stuff, of course. I have some artic silver that I used for a PC-cpu-to-heatsink application. Can I use this, or do I need something different?
    I was wondering the same thing.

  15. #115
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    Quote Originally Posted by varider View Post
    Can't you just put some thermal paste under the board and be done with it? After removing the old stuff, of course. I have some artic silver that I used for a PC-cpu-to-heatsink application. Can I use this, or do I need something different?

    Who in their right mind tests a high powered led light without some airflow. It makes all the difference in the world. Most light manufacturers even tell you not to use their lights on high when not moving. This goes all the way back to days when TurbuCat halogen lights were all the rage.

    I don't think it's right to trash the reputation of a light with testing doesn't replicate real-world use.

    This is a pretty nice light in my opinion. It has an near ideal user interface. It's small and compatible with industry standard battery connectors. It has a spot-flood combo beam that's very nice although not perfect. And it was a very good deal at $32.
    You cannot put thermal paste under the board simply because there is no contact area under the board.

    Operating the light with no airflow or operating it with airflow is the same thing, because this light has a thermal sensor that steps power down at 70C.

    Even if the airflow keeps the light at 50C, leds would still be at really high temperatures because there is no contact area between leds and case.

    This light is very well engineered in every aspect but thermal management.
    For it to be perfect, we have to do something to increase thermal transfer.

    please trust me, I am really passionate (and knowledgeable) about led lighting and seeing this thing is like an civil engineer that sees a bridge made with toothpicks

    Please note that I am here not to destructively complain about this light but to make costructive ideas arise from this issues.

    Pics will arrive this very day, I am sorry for the delay.

  16. #116
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    That's cool.

    From what I gather from your posts, there is some sort of gap behind the led board. Is that right?

  17. #117
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    well, actually there's nothing but a giant hole behind the led board

  18. #118
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    Quote Originally Posted by bozma88 View Post
    well, actually there's nothing but a giant hole behind the led board
    Holy hole-in-the-wall bozman!...

    Well that does put new spin on the issue. Just what is the board made of and how much contact does it actually have with the metal part of the lamp? If you can supply a photo it might inspire some ideas on how to improve the thermal issues.

  19. #119
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    Okay, I decided to investigate a little further. I took the front off again and started poking around. I also removed the rear. From what I can tell the back of the board is metal. How much metal I can't tell. How much of that metal is contacting the lamp body I can't tell either. The edge of the electronics board is backed right behind the back of the MCPCB board so really not a lot of wiggle room if you catch my drift.

    I did poke around the front of the board to see if it would lift up but I really couldn't make it move. Whatever is used to hold it in place is doing a pretty good job.

    Something else I noticed, I took a bright LED torch and shone it in the front towards the back while I looked from the back to the front. I could see the outline of the metal ( MCPCB ) around most of the board. This is not inspiring. Only in a couple small areas was the light not able to penetrate. I have a feeling Boz is correct, there is not a lot of contact area with the metal area of the lamp body ( and metal area of the MCPCB ).

    Personally, I can't see myself trying to remove the MCPCB unless I know I can replace it. I figure If the contact area is that small nothing you do is going to make that much difference ( unless you can re-engineer the front of the lamp ) . If you try to remove the board you might end up destroying it in the process. Now if I could get another board the same size and shape as the one already there ( only with better emitters ) it might be worth trying to remove the one already in place. As it stands, the board in place looks custom made with the emitters embedded into the board. Destroy the board and you might as well toss the lamp into the trash.

    Nope, this is not looking like an easy mod. For me, not a big deal, I have better lights. Still the lamp works, has a good UI and provides a decent output and beam pattern. Output will drop WHEN the lamp gets hot. That I already knew. How long it will last if you use the lamp in it's max output mode for extended periods is anyone's guess.

  20. #120
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    Quote Originally Posted by bozma88 View Post
    well, actually there's nothing but a giant hole behind the led board
    Pics will arrive this very day, I am sorry for the delay.
    Holy ... not easy to take a foto of the whole hole ...

  21. #121
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    Ok, now I understand.

    Wow, that sucks! I just assumed there was a solid wall behind the led board. Oh well, not the greatest design. That's why it's so small, they left out the thermal conduction wall! I wonder how long it will take to fry itself.

    So that leaves the Solarstorm x2 and dx ultrafire D-50 as possible good and cheap dual-emitter lights.

  22. #122
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    Looking forward to the fix.

  23. #123
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    Quote Originally Posted by mrradlos View Post
    Holy ... not easy to take a foto of the whole hole ...
    Unfortunately my job has much priority and I found myself having no time at all until now. Sorry for the delay.

    UltraFire D99 a promising new 2x light?-case.jpgUltraFire D99 a promising new 2x light?-mcpcb.jpg

  24. #124
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    Okay, pretty much looks like what I expected. There looks like there's a small lip that goes around each of the emitter areas and that is the only contact area that you get for the emitter board.

    Boz, your board looks undamaged. can you explain what you did to remove it.

  25. #125
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    That is crazy. Just when you thought you had seen it all



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