• Howdy! we're looking for donations to finish custom knowledgebase software for this forum. Please see our Funding drive thread

200w led headlamp 10-16k lumens Diy build

bionicdan said:
Yeah the one I used was just pwm (for small motors?). The buck or boost ones held out nicely under throttle.

This guy has 80+ volts to deal with so I personally would just run 4x18650 that would suck around 1.5amps boosted to 35v at 500ma for his led chip. 2 hours run time there and very small package :)

that sounds like a good idea also.
iv got spare 18650s all over the place...

i bought a few things for the build under sleep deprived hypnosis last night in the small hours :p

i got a little pwm controller,

a step down transformer (could be run from a small ac adaptor that gives 12-36v output from the 84v pack, or a few 18650 as you said)

and a rather expensive cree cxa3050 led, 3000k (did not want to be dissappointed with the cheaper ones as i saw they were ofted low quality/dodgy, on utube)

the led is a pretty big outlay, but the other things are cheap enough im willing to try a few to get the best/compact system.
i like the digital voltage/current readout on the step down converter, but its probably not really necessary.

i was thinking the pwm could be coupled to the output of the step down to use as a dimmer, that way there wont be voltage sags etc, but its probably not the most compact system.

the last thing i need to decide on is the lense/reflector, as im not too sure the cree leds have matching lenses available cheaply(couldnt find yet)
i guess it could made from the epistar type lense/reflector with some diy adaptations.
Dont forget a good heatsink and/or housing. I ran a 100w led at around 50w in one of these with added heatsinks and vent holes but with such a tasty led I would recommend installing a thermal switch. It got to 80 degrees in 5 mins over 50w. If you wanna run more you need a bigger heatsink or housing.


They can make or break a circuit to either force your led to a lower power setting or cut it entirely. You can install them with thermal glue near the led.

thats awesome!
ill definately install one of those switches.

so i guesse somewhere ~ 80C would be a good cutoff?

@heatsink, i have several lying around i have saved for just such a purpose.

I think the pond light you linked looks cool but the only problem i can see is that its stainless steel, which is a really poor conductor of heat.

ill definately be looking for aluminium housing, copper heatsinks are also possible but i might diy it cause they are so expensive to buy ready made.

btw, would you reccomend this stepdown over the one i got or will it do much the same thing?

it would be nice to use a switching type, and not the other type that wastes a lot of power as heat.

a really relevent thread on budgetlight forum here-


  • heatsink.jpg
    36.2 KB · Views: 739
Honestly I think you know as much or more than me lol But the link you sent is a step up converter. so the source input always has to be lower than the output.

The pond light is alu but the main plate for mounting the led is only 3mm thick but it did pass the heat quickly to the 10mm thick body. This very housing I blew an led in at 90w because my 80 degree switch failed to heat up as quick as the led did. So I would recommend 70 degree max. depends on your design though.

These huge heatsink are for bay lighting or stationary applications. you can easily half the size as long as you make sure your moving while its up hig

I always used cpu thermal paste for my builds. Recently found some liquid metal ones with the best transfer rates but I just used cheap china crap.
im still up late cause i was bidding on a cxa3070 chip(and won! :p ) oh im getting hooked on this stuff now :lol:

so ideally for me i need a stepdown that will give me cc cv 33-42v(aprox) from my 90+v hot off charge pack. if i dont use a bunch of 18650 separate pack to get the ~42v from a lower voltage.

i wonder if there is such a thing that is compact enough...?

if the pond light is alu, im interested. i thought it said s.s.

currently im thinking a copper cored pentium 4d fan heatsink would be awesome, even if i ripped the fan off. 90mm dia, and heaps of surface area to catch the wind.
if i have a dimmer, i can always turn it down if im stationary for long, add the temp switch ofcourse.

The back of the pond light is threaded exposing the rear plate that contacts the led. I glued on a 20mm square heatsinks inside and vented the back plate. I toyed with oil filled but it looked hard to seal. If you could fill the back portion with oil it would never overheat but doubt you need full power for longer than ten minutes at a time anyway

oh yes iv used cpu heatsinks. it looks messy but never blew an led
so after a brief intermission(~1 year :lol: ) I am back on the 100w led spotlight mission again.

I have played around with boost converters , pwm controller and the cree cxa 3070 leds, really impressive light output, but i would really like to find a more compact option.

the boost converters are heavy and a little too bulky for my liking. most of the bulk is the huge heatsinks they have for the mosfets, and im thinking that could be fixed by adding a smaller heatsink that will get good airflow on the bike.

i have not been able to find a cc cv step down module to take the ~90v battery voltage to get, say 72 volts for 2 cxa leds in series(ultimate goal)
so at this stage its looking like using an ac adaptor to get 90v to 48v, that the boost can make 72v,(what a f** around) or just going with 8 or so 18650 and boosting that to the required 72v @cc. probably more sensible.

just thought there might be some out there that have overcome similar voltage adjustment issues in the past year and might like to shed some light.