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Discussion Starter · #1 ·
I finally have all of the parts together for my new Cree XR-E triple handlebar light. I designed the housing from scratch and had the parts CNC machined at work. It was designed to use all readily available components (I got most of mine from Cutter). It will use 3 Q5 bin XR-E LEDs, a Bflex driver, and some 3mm LEDs and a waterproof switch from Digikey. Optics will be 20mm Carclo, probably 2 20 deg. and one 10 deg. First pictures are below, and I will update as the build progresses.

Mark
 

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Now that you've got that program for the sweet housing, wanna run a few more? Nice job, I'd like to be first in line!
 

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Discussion Starter · #3 ·
RobW said:
Now that you've got that program for the sweet housing, wanna run a few more? Nice job, I'd like to be first in line!
Do you really think I went through the trouble of setting up the machine and only making one;) ! I did run a few sets of the housings, but they will most likely be going to my riding friends and 24 hour team partners!

I do have one question concerning run times. I did a quick calculation to determine how long the battery will last, can someone please comment if I did it correctly:

Battery is 14.8v 2.6 Ah, which comes to 38.48 watt hours

The LEDs will be run at 700mA, and according to Cree will draw 3.5 V at 700mA.

That makes 3.5 * 0.7 = 2.45 watts * 3 = 7.35 watts for 3 LEDs.

38.48 / 7.35 = 5.24 hours run time on high

Mark
 

· fuggansonofahowa
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bikeny said:
Do you really think I went through the trouble of setting up the machine and only making one;) ! I did run a few sets of the housings, but they will most likely be going to my riding friends and 24 hour team partners!

I do have one question concerning run times. I did a quick calculation to determine how long the battery will last, can someone please comment if I did it correctly:

Battery is 14.8v 2.6 Ah, which comes to 38.48 watt hours

The LEDs will be run at 700mA, and according to Cree will draw 3.5 V at 700mA.

That makes 3.5 * 0.7 = 2.45 watts * 3 = 7.35 watts for 3 LEDs.

38.48 / 7.35 = 5.24 hours run time on high

Mark
In a most ideal condition, it looks correct. That's assuming a full charge, no cabling or heat or controller (buck) overhead losses, a linear discharge curve, discharge rate losses, warm climate, etc.etc.

Just figure on around 5 hours.

That's going to be one blindingly handsome unit, there......nice job. Keep us posted.
 

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Nice work Mark!

Have you thought about machining a few fins in to that beauty to save a bit more weight? I guess it would be pretty lightweight as it is anyway. ;)

I’m interested in how you’ll mount these lights too, it looks like you’re going to use two mounts?

Keep up the great work, and be sure to keep us posted! :thumbsup:

Dave.
 

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bikeny said:
Do you really think I went through the trouble of setting up the machine and only making one;) ! I did run a few sets of the housings, but they will most likely be going to my riding friends and 24 hour team partners!

Mark
But you wouldn't mind sharing the drawings or CNC code?
 

· fuggansonofahowa
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Low_Rider said:
Nice work Mark!

Have you thought about machining a few fins in to that beauty to save a bit more weight? I guess it would be pretty lightweight as it is anyway. ;)

.................

Dave.
That's a good idea - it would help with heat dissipation with the added surface area also.
 

· fuggansonofahowa
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Low_Rider said:
He's got a fair bit of surface area so it will be quite alright as it is. It certainly wouldn't hurt just for a little extra style. :D

Dave.
ahhhhh....but if the added density of the casting cannot shed the heat through it's outer surface area, that case could become an insulator of heat. Typical electronic heatsinks aren't just blocks of aluminum (or copper). They have fins on the outside for greater surface area which equals greater heat dissipation. The ambient air pulls the heat from the fins, the fins pull the heat from the sink, the sink pulls the heat from the component. When the surface cannot shed the heat, the heat stays put. I haven't worked with these LED's yet, but to take a lesson from electronics 101....heat = bad. Most failures are due to heat related issues. It's not just the LEDs, but the controller (bFlex/Buck Puck/etc.) that may be affected too.

As compared to achesalot's...the surface area to density ratio is much less. (The bling score is very much higher, though). When it gets warm, it'll stay that way for some time.

Honestly, I don't think this will be a problem here, especially at 700mA. IMHO, the more we push these puppies, the more this heat issue will need to be dealt with.
 

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Discussion Starter · #13 ·
Next update

Thanks for all of the friendly comments! I have done a little work the last couple of days and have almost all of the wiring done. First of all, I should have made the back part of the housing a little longer! It was quite a job to get all of the wiring stuffed in that tiny cavity! The biggest problem was strain relieving the cable so that it doesn't pull out of the housing. Anyway, as you can see from the first picture, the Bflex is wired up and mounted inside the housing. The second picture shows the cable, switch and 2 LEDs. There is a green LED that will always be illuminated when the battery is plugged in, and the red LED is the low battery warning. Last picture shows the optics siliconed into the front half of the housing. 20 deg. optics on the outside and a 10 deg. in the middle will be my first try. Now I just need to mount the XR-Es with some Arctic Alumina and assemble the 2 halves, hopefully later today. Also, to help with the thermal transfer between surfaces, I have sanded all of the mating surfaces on a granite plate with very fine sandpaper to ensure good contact, and the Arctic Alumina will be used on all mating surfaces, including between the front and back halves of the housing.

As far as everyones comments about adding more surface area, I agree, more would be better. But I think I have enough to keep the unit cool while riding, and the fact that they will be run at 700 mA for now. I am already thinking about the next revision!

Mark
 

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Nice!

Can't wait to get my order in. (LOL)

Had a few ?'s.

How many lumens do you think it'll put out? Is there any reason you didn't use the Seoul's and drive them at 1000mA w/ a 4Ah battery or even 2.7Ah AA batteries.

I'm just now trying to understand LED's and how they run so sorry if the ?'s are lame.

MB
 

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Discussion Starter · #17 ·
mb323323 said:
Nice!

Can't wait to get my order in. (LOL)

Had a few ?'s.

How many lumens do you think it'll put out? Is there any reason you didn't use the Seoul's and drive them at 1000mA w/ a 4Ah battery or even 2.7Ah AA batteries.

I'm just now trying to understand LED's and how they run so sorry if the ?'s are lame.

MB
Here are my reasons for my choices: For the LEDs the Q5 bin Crees are brighter and more efficient than the best Seoul LEDs available. BTW, the Crees can also be driven at 1000mA safely, but I opted for 700mA right now in order run them more efficiently and have a longer lasting light.

Approximate lumen output will be as follows: The Q% bin LEDs put out between 107 and 114 lumens at 350mA. Multiply that number by 170% for the output at 700mA = 181.9 to 193.8. So for 3 LEDs that comes to 546 to 581 lumens. If you take into account the lense, get something like 500 to 550 lumens.

As for the battery, my 2600 Ah 14.8V battery will last about 5 hours on high, which is plenty for my needs!

I hope that answered your questions!

Mark
 

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Discussion Starter · #18 ·
I have one more question for anyone who can help: I am looking for a good way to mount my 4 cell Lithium battery to the bottom of my stem. Maybe like some kind of padded velcro bag that can be strapped to the stem? I think that would clean up the whole mounting arrangement. Any suggestions would be appreciated.

Thanks,
Mark
 

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bikeny said:
I have one more question for anyone who can help: I am looking for a good way to mount my 4 cell Lithium battery to the bottom of my stem. Maybe like some kind of padded velcro bag that can be strapped to the stem? I think that would clean up the whole mounting arrangement. Any suggestions would be appreciated.

Thanks,
Mark
Cool light.

I use this for my Edge battery pack on longer events: http://www.polardiscount.com/scripts/prodView.asp?idProduct=110&src=fr

I mount it upside down on my stem, as opposed to right-side up on my top tube, to keep it away from my knees. There will be extra room. I pack a small piece of foam and a couple of emergency gels in it to keep things from sloshing about.
 
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