4000lm head/bikelamp build

ronckers

Newly Enlightened
Joined
Oct 19, 2016
Messages
1
Hi,

New to the forum and thinking about building a nice headlamp for running and mountain biking. Hoping to get your input on some ideas! Will post progress of this project in this thread.

Looking to output about 4000 lm so my initial idea is to use 5 pcs of the Cree XM-L2 with cu base outputting about 800 lm/pc. To start - is this sensible in terms of realistic output? See below.

https://www.led-tech.de/en/High-Pow...E-XM-L2-U2-on-Copper-PCB-LT-2078_120_170.html

I would like to use small <20 mm diameter reflectors for the 5 leds with varying output angle - can you recommend good quality reflectors? Maybe even an initial setup? I would like these to be exchangeable so that I can change the angles of output. Initially looking for a nice wide beam but also a long throw in the center, hence 5 leds.

On the electronics side I'm in real need of help!! I would need your recommendation on a driver and hoping to have low/medium/high output with the high output lasting ~2hrs. Any ideas? Needs to be ready made as I'm not good with the soldering iron (connecting the leds will be a big enough task!).

The housing will be machined out of an aluminum block (will post images as soon as the first design is finished) but need some of your input on the above before I can finalize the first draft.

Thanks!!
 

Steve K

Flashlight Enthusiast
Joined
Jun 10, 2002
Messages
2,786
Location
Peoria, IL
Nice to see someone putting together a project... a fun way learn and be creative.

The first step to any design is to figure out what the device is supposed to do and be. i.e. how bright does it need to be, what should the beam pattern be, how long should it run, how much should it weigh, does it need to be waterproof/shockproof, what thermal environment will it be operating in, etc.

The best way to do this is to look at other designs and decide what you like or don't like about them.

My impression of your requirements is that 4000 lumens seems like quite a bit. This will require 40 watts of power, roughly, which seems quite large. This will require a significant heatsink to keep the LEDs at a safe temperature. As a general rule, the heatsink shouldn't be so hot that you can't touch it. Have you run the calculations to estimate the size of the battery pack required to provide 40 watts for the desired 2 hours?

Anyway... my lights usually use plastic optics, such as are made my Ledil or Carclo, and I make my own electronics. I buy my parts from Digikey or Mouser, typically. For folks that buy drivers and other bits from suppliers that are oriented towards flashlight hobbyists, my understanding is that places like Mountain Electronics, https://www.mtnelectronics.com/index.php , or LED Supply, http://www.ledsupply.com/ , are pretty good.
 

camelight

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Joined
Apr 9, 2016
Messages
189
Location
israel
I think 5 xml light would be to large for an headlamp even if the batteries are in outer box (well for so many lumens it would have to be)
But you can use a cree xhp70 that can provide 4000lm (even 5000lm)
Either way if you use one xhp70 or 5 xml if you want it to be notto large it would be a floody light
If you more throw you can use a cree xhp35 that can provide 2500lm and because of it's smaller size you could either have a smaller light that would be better for an headlamp

But there is a very big broblem on this powerful flashlight the heat problem
On an headlamp i don't think it would be very nice
And it can't be to massive so the heat wouldn't be a problem it would be just to heavy

My advice is to give up some lumens and use a cree xhp35 with not more than 2000lm even less with an outer battery pack of 2* 26650 batteries or 3* 18650 they should give 2 hours of runtime but it would get weaker as the voltage drops
So i think 4 18650 is the best option

You also can build another flashlight for your bikes using a xhp70 ( or xhp50 for more throw) with 3000lm and outer battery pack with 6 18650 (so it could run on full power for 2 hours without weakening)
It can be bigger for batter heat distribution plus the wind causing from riding would help cooling it
 
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