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200w led headlamp 10-16k lumens Diy build


1 kW
Dec 22, 2010

I looked up many very expensive lights and the outputs arnt great, its another battery to charge and another thing to carry when you go in the shops.

So I built my own non detachable light to run from my motors battery back. It has two leds bolted onto a miniature security light housing. Each led is rated at 100w/3.2a at 35v. The epistar led chart says these make 5000 lumens at 1.3amps each. This is generally the current I run at for long runs on dark lanes.

My controller is a small pwm motor controller with variable potentiometer. If you put a switch in the pots wiper yellow wire this activates between 50% or fully variable control(ie 0-100%). If you put a break in the black pot wire it activates 100% or defaults back to fully variable (I dont recommend running over 2amp per led on a dual led setup or in warm countries due to heat issues). Heat seems to double every 800mah over 1300mah and light output only goes up 10 percent at a guess. I tried a constant current driver but again this seemed to double heat so I am sticking with pwm and putting up with noticable flicker in the first 3-5% of illumination.

In still air it starts to feel warm/hot but once your doing 15mph upwards it barely feels warm in cool night time air. I think 200w is a bit overkill and running one led might be better for long rides. But I knew I could fit 2 leds and know they run cooler and more efficient the less hard you drive them so I just had to try lol.

Slapped in some cpu grease and bolted them to the previously 10w led housing. I used a small knife sharpening stone to flatten and protrusions left behind from the old screws.

I then mounted my lenses. I only had one focusing reflector so only one led is directed forwards until I order another one. So one led is firing at about 140 degrees and one about 60 degrees. The lenses stopped the glass going back in which is a shame but I sealed everything with silicone and it has the added benefit of extending my cooling area mass so I can run max power without worrying.

4x35mm P clamps later

Its very light and very solid with no vibrations on a ride.

*I am getting round to the pvc battery jacket but cant feel my fingers in this weather, dont freak out.

No video or image seems to reflect the true brightness of this but heres a little video I did to test my new chinese cheap action camera at night. Here is a clip showing how to utilise the lights dimmer switch when drunk people stumble out of hedges. Dimming on acceleration is not normally as bad but freezing temps recently made my battery sag. I couldnt go down the bridal way due to boggy mud so heres some lanes action.
Taken with this $33 camera with Mp3 player and 1w led woo 1w I say

Heres my parts list

2x100w led at £12 each (the newest one has 45x45mil chips not 40x40mil like the old one)

10w led security light 12v or ac mains £11

Lenses/reflectors £5

pwm motor controller £5

Clamps £3.

So with one 100w led you get 5000-8000 lumens for £35 or with 2leds you get 10.000 to 16.000 lumens for just under £50. Its a choice between mental bright or a bit more mental bright. Once your eyes adjust the extra 100w isnt really noticed so if your on a budget just run 100w.

I run warm 3000-3500k colour temp leds. 3000k is a bit muddy orange and 3500k is just like the sun. Warm and doesnt piss people off on very low. I tried a 50w 5000k before and even on minimum everyone kept moaning as it looked nasty/harsh/piercing. The bright white gives you no contrast to the road and makes everything and everyone look washed out and grey. No good for pot hole spotting at 30mph.

My 10amp (supposedly) driver ran 1.9amps max into one 40x40mil led and more like 4amps into the pair. Its as if the led commands the limit to a degree, which I know leds arnt capable of hence needing a driver in the first place. So what Im saying is they arnt as easy to overdrive and blow up on pwm as I thought. Perhaps my multimeter shows the load wrong as it is pwm and maybe I am pushing more? Like measuring ac load on motors, the load is often faked by the power factor. I wonder if its effected my readings

Heres some links that may expire sooner or later

Led data sheet showing that you can run 2amps like me even if it gets a bit hot (full 3a up to 60 degrees maybe 1a at 100 degrees). I had some thermal switches rated at 60 and 80 degrees to make a warning light but as it doesnt get hot in cold night air I havnt bothered instaling them

100w led with newest big epistar 45X45mil chips (I think rated at 3watts each chip underdriven at 1watt) OH YEAH IF YOU ORDER FROM THIS GUY YOU MUST SPECIFY 3000K WARM OR HE MAY SEND YOU 5000K COLD. 5000K WILL GET YOU PULLED OVER EVEN ON 3% ILLUMINATION ITS NASTY

pwm controller and pot

security lamp (select ac and get a free driver for projects, 12v runs no driver?prob blow up)


Heres a constant current boost converter that takes 5-32v input and makes it 12-35v output for leds and such. I ran this at about 2.5 amps and thought it was going to set fire to the led. You would need bigger heat sinks for this setup which is too bulky for my liking.

Final thoughts. I dont think pwm is really a form of current control its just on off on off at pretty much direct current. Direct current (a battery straight to an led) will blow it 9 times out of ten. I think perhaps I have got away with it by keeping in the 30v (33v motor resting) range, reducing possible ampage.

I am also running fairly thin doorbell wire and getting my main positive feed from my balance socket which also has a short length of 18awg to travel down. I suspect if you run 33v -35v on some nice cells with beefy wires you could get a melt down. Make sure you test the ampage with a voltmeter. Mine says 4a at 75% but the meter stops registering any gain after that. basic voltmeters cant deal with such high frequency pulses and will give you poor readings but its a good start.

So I have just observed heat, compared it to the stated ampage and not run it at 100% for longer than a few minutes at a time. I feel safe running 50-75% constantly. Just as a test I am upping the voltage to 11 life headway cells 35v this week and adding some extra heatsinks. This is mainly to avoid the dimming up the monster hills in the freezing cold. My batteries sag more than normal recently drawing 40amps (phase or battery i have no idea as I cant get infineon software to work on win7) and a teeny 10ah battery. Its not so bad in warmer weather.

If consistency is more your thing over full on sun beams I believe my old constant current blue driver will self adjust to the voltage you specify. So if you ask for 33v and your supply pack dips by 10v under load it will just temporarily trim it up for you instead of the led dimming or going off up that hill. Due to extra heat you would be stuck at 1-1.5amps max for long runs and no easy on the fly adjustments other than on off as a main beam. My 20ah battery didnt suffer like this so much and it was also stiffer prismatic cells.

*update on 11 lifepo4 cells. Multi meter shows almost 6 amps between driver and leds and is variable right to the end of pot travel. Dimming under acceleration up long hills seems to have gone. It doesnt seem to be that much brighter but may have raised the tint to 5% whiter. I would stick with 33v if you have a bigger pack capacity than my saggy 10ah headways or a smaller ampage motor so it limits the draw to 4a max to the led.

Ok I was pretty sure this would happen but my curiosity made me do it for the greater good. At 36v on a 90 percent charged 11 life cells I partially blew one of my leds at 6amps/ie full power pot interupted. The leds arnt matched in chip sizes and I had meant to check the draw into each one seperately but forgot. So my newer big chip led must have drawn more than the old small chip led and drew too much current.

Had I used two matched chips I dont think this would have happened but Now recommend a well matched/adjustable driver how ever many leds you run. Also keeping in the 30-33v mark seems to be safest after running like that for nearly a year previously. I will probably just slap the single led in the middle or use the partially blown one as a low beam.

The advert for my driver has been updated and it now says it can handle twice the power and voltage than it said when I ordered. They must have made a mistake and this probably didnt help as I thought it was 48v 10amp max. Being chinese amps then more like 5 amps. The cheap led may have just been bad but theres too many variables and my lack of proper procedures mean you cant point the finger really. Rip 100w led. I wonder if it will still draw 100w with only 50 chips lit up?
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15k lumens is beyond intense. It's what you might expect to see on the landing gear of an aircraft or something.

I don't know if there are any laws about brightness on the road anywhere, but that'd be a pretty harshly overkill on the amount of light. I'd be worried about blinding drivers, seriously. I've seen some cars with very obnoxious lights, I don't know how bright they were but it certainly was too much.

In addition, I assume you are running on batteries with an ebike. Running those lights at full blast would probably take a hefty amount of range off your trip. Personally, I was thinking of aiming between 400 and 1000 lumens. I think most car headlights are between 800 and 1000.

Awesome build anyway though, very inspirational. Thanks for sharing!

How do you turn it off? Is the pwm all the way to one side considered off? Or maybe the controller's switch will take care of that. It'd be silly if you accidentally left it on and killed your battery with it.

I think I'd go with something much smaller, at least half as large, I don't have much space for placement.
Yeah there are laws and yes it would stop a car in its tracks. I use it down off road tracks or on unlit lanes at night like a full beam. Just like a full beam on a car is illegal on all the time I just dip it down when I see a car coming. Cars used to fly up to me on unlit lanes not see me till it was too late and nearly throw me in a hedge while blinding me. Now they see a huge light and respect my space and slow down or pull over. Of course by then I have set the light to min and a bicycle pops past at 20 mph. Much better

So I set the potentiometer on my battery bag between my legs to very low. Just enough to see where I am going and not enough to make anyone cry. So by interupting the negative pot feed it flicks between full and very low at the flick of my motorbike handle bar switches. Or I can just use the variable control via the pot but its hard to find when your going fast. I never use anything other than low in busy street lit places as there is no need.


Ok my range is currently 14 -20 miles on a 40amp controller that involves monster hills. When I ran 1 led I used 1amp max. 1 amp hour while running 10-40 amps seems pathetic compared to the wicked output so I am happy with that. If its ever an issue I will put 8x18650 laptop batteries together for it.

My usual round trip is 30 mins, half in darkness/offroad and half in streets. So I only draw 4amps if im feeling silly for 15mins =1ah. I have marked on my bag .5 1 1.5 2 and 2.5 amp hour marks. Between 1 and 1.5 is similar to my car so the draw can be 0.3ah depending on your mood lol

The capacitor onboard does not power down as such while unlit. Its like leaving a small motor controller for your ebike hooked up. Over weeks or months it could probably damage something.

So my data tool system 3 alarm and leds are hooked into the same loom from the batteries beefy balance port I had installed. After the ride I have to remove the plug to charge so know I wont forget. While in shops i just leave it turned down/off though.

I would recommend you stick with 50watts then. The main reason being is it was easy to find collector bases and lenses for the 50w and 100w leds but nothing for the smaller ones. With my collector in place it doesnt blind you if you stand off to the side on low. But if you just sit a lens uptop of an led its too focally close and spreads out 180 degrees. You must fit the plastic reflector for any chance of a focused directional beam. Look how small my 50w build was. Its like 5cm cubed mounted on an old amd cpu heatsink. This is my 100w test build and picture of 50w led mounted on a heatsink sat on my security lights housing for size reference (second pic down and on the plate at the bottom)


Its great to get so much from so little money and have a hand in your own design elements

I just noticed 20w and 30w leds on this ebay advert. Just remember the higher you drive a small led the higher the waste in heat. Its like running a motor at 500w when its rated for 1000w. You know it will get hot at 1000w and they prob lied on the specs lol. I believe incandescent bulbs put out 10w of light per 100 burnt, so 90w is literally burnt in heat. So its not easy comparing car head lamps. I think leds are the opposite like 90 percent light 10w of heat. Its prob not exact but you can look it up its something like that.


So If you have some old spare parts like cpu cooler you could make a very bight light for about £10 utilising your battery pack. Of course at full tilt up hills mine dims by half. I just felt in a silly mood and thought I would try having helicopter landing lights on my bike ha ha
Maybe you could splice an on off switch from before the power+ gets to the "DC Motor Speed Switch Controller"

This is brilliant though, thanks a ton for sharing it. I love the thought of making this thing. I was considering various lights weighing all the pros and cons, thinking of some of the lights online for sale that can switch between high and low with a button press now seem to suck to me compared to being able to have a full range of options.

Ah, I was about to ask about setting the voltage right for the LED and saw you added "Heres a constant current boost converter that takes 5-32v input and makes it 12-35v output for leds and such. I ran this at about 2.5 amps and thought it was going to set fire to the led. You would need bigger heat sinks for this setup which is too bulky for my liking.

http://www.ebay.co.uk/itm/350553798847? ... 1438.l2649"
:shock: Even though I'm sure these are too bright I gotta get some. Same seller has them with the electronics to drive them too. They say AC 85V-265V for the driver board, but I'm going to take a shot with my 74V nominal DC. I just hope there's some way to trim them below half like the OP, so my housings with heat sinks I have will work. I'll definitely need some kind of reflector to point them higher without blinding anyone.

100W LEDs Yay!
If you use pwm its up to you how bright they are lol. From barely on to omg the bikes going backwards. I saw a science programe once that calculated the cars headlights slow you down.

all 100w leds will be 35v. They are made of 3v leds in strings of ten. So you need to access half way down your pack or run a buck converter

Only trouble with these nice blue units is tiny adjust screws.

Just get a multi voltage pwm controller like I linked and try to find a way or getting 33ish volts to it. It will run on 8 ping lifepo4 cells or 9 headways minimum for me. 8 headways sagged to much up hills and the light almost went out.

Dont just treat a 100w led like an on or off device. it will be totally unusable on the road and will cause crashes and/or your death. You must include an easily variable driver or use it as a supplementary main beam, falling back onto your regular lights when the public are present (cars pedestrians badgers etc). Those ac drivers are fixed current at 1amp. This is what 1amp looks like on my single lower specced 100w led
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bowlofsalad said:
Maybe you could splice an on off switch from before the power+ gets to the "DC Motor Speed Switch Controller"

This is brilliant though, thanks a ton for sharing it. I love the thought of making this thing. I was considering various lights weighing all the pros and cons, thinking of some of the lights online for sale that can switch between high and low with a button press now seem to suck to me compared to being able to have a full range of options.

Ah, I was about to ask about setting the voltage right for the LED and saw you added "Heres a constant current boost converter that takes 5-32v input and makes it 12-35v output for leds and such. I ran this at about 2.5 amps and thought it was going to set fire to the led. You would need bigger heat sinks for this setup which is too bulky for my liking.

http://www.ebay.co.uk/itm/350553798847? ... 1438.l2649"

The voltage is listed in the ebay specs but as they are 10x 3v leds in a string or ten rows they always add up to 30-35v to operate. The closer I get to 35v the more amps get eaten so I like 33v to help limit the heat. Leds will super heat and blow if you use them for 5 seconds with no heat sink or with no current limiting device.

The trouble with a switch is the inrush spark. I had to install an anderson conector on top of my detachable balance harness to avoid damage to my balance plug. The anderson is taking the small pop but a switch may not. Also most my pwm drivers go full power for the second you connect power even if its set to low. this is like a lightening bolt at these lumens and will cause you trouble hence why I chose to switch the potentiometer wires not the power wires.

I also tried cutting the middle pot wiper wire which seemed to activate 50% power. But then also added a second pot running through its middle leg and one outer leg. This kind of gave you a bit more control. My plan was to have various pots at set increments but got bored KISS! Glad I have illuminated some lives ha ha see what I did there, enjoy.
Hah! perfect way to get the nanny state to crack down on these new 'binding, kid murdering' lights.

Please be reasonable!
bowlofsalad said:
"this is like a lightening bolt at these lumens and will cause you trouble"

And blindness.

Ha yeah its the people headed towards you with big metal things that I wouldnt want to blind when I decide to power on my system or something. Never look into these lights, I looked at 10 percent power and saw spots for 20 mins. very pretty

NEPTRONIX if you read the thread it has been aimed at my off road use and with the main intent of having a very low setting to not blind anyone but a high when out of town or when some other ignorant is keeping his mains up.

There is a crew of 20 cyclists with hope £200 headlights that are road legal in my village. They previously have blinded the crap out of me. As bowlofsalad suggests not many lights offer easy access to high and low so we make our own lights to determine our own preferences. If they do its some stupid button you have to hold while rubbing your belly and patting your head ha ha. A cars headlights on main beam will blind anyone. But your allowed to use them in the right scenario.

Its in the interests of my own safety to keep it as low as possible with oncoming traffic but bright enough to make me noticed. Its merely a marker when on low and doesnt even hit the floor infront of me much, but in street lit areas thats all I need

My pwm setup offers infinite control not just high and higher :)
Just for those interested, here are my comments regarding this ssytem in it's previous thread:

(personally I think this thread should be part of the original one, not a separate thread, but it's up to the OP).
amberwolf said:
Just for those interested, here are my comments regarding this ssytem in it's previous thread:

(personally I think this thread should be part of the original one, not a separate thread, but it's up to the OP).

Hi amberwolf cheers for your input with this. Hopefully someone can utilise your info. I get very tired since i hit my head and struggle with lots in one go so just took the easiest options towards the end.

I have now found a nice low setting that doesnt dazzle anyone as you can see in the photo dimly lit (unless your 1 foot away looking into the lamp). Maybe a higher pwm switching frequency would be better than I have, but it isnt terrible.

My first post was about replacing pots with set resistors. I did wonder if I should just add it onto the first one. As you can tell I dont often use forums but just hoped to share a few ideas with like minded people. Maybe a moderator can delete this and add it on to the first one. I also noticed the first post was in general not general ebike so that was another reason to make one here as the first was general electronics and the second is a permanent fixture on an ebike. Cheers Dan
ok so iv been looking for some decent lights like this for ages. after frustration from some lights not living up to claimed spec or not even working at all on arrival, id love to build my own.

unfortunately the links you posted for obtaining the leds seem to have expired :|

any chance you still know a good source?

any help much appreciated
+1 ,that was the other reason i forgot to mention. massive brightspots in the center that even blinds me :lol:
need lots of light in a wide beam.

btw, all the 100w leds seem to work on 32-35 volts.
is there any chance a similar amount of light could come from a 12v version, or praps several of them?
makes it easier to use with a 12v dc/dc
You can do anything you want but if you want a wall of light I prefer the 100 led chips (45mil chips are almost the biggest and harder to blow).

Cree mt-g2 are easy white 6v 2000lumen one inch leds. I often wanted to try two on my handle bars for compactness

below are the newest highest lumen per watt range and have a wide array of options


search ebay for 100w dcdc step up or step down and all sorts comes up. You have to be careful because some have an inrush current that will blow an led. the blue boxs ones are ok but hard to add on the fly adjusters.


look for 45mil 100w (or 12v) warm led. dont try 5-7000k bright white its awful and pisses everyone off even on low. 2800-3500k is nice and warm and shows the potholes up better.


im sure theres better places to buy like mouser or cutter or digikey. just google it :)
awesome! thanks for the reply with updated info.
im definately going for this holy grail of ultimate offencive headlamp :lol:
.. no seriously now, with the right diffuser, i think it might be possible to see everything and not piss everyone off aswell
so iv had a look and found this-
and a psu like this for getting 36v from the ~84v battery voltage (i have found these ac adaptors consistently work very nicely as a dc/dc also)-
still need to find a driver, but am i on the right track :) ?
nice enough led, such low current for so much light :)

heres the bin chart (it lists 500ma but think you can go higher)

Im afraid im not educated in electronics Iv just bought things and experimented (with occasional smoke). But I wonder if you could get 2x 45v buck converters and run them in series so they only see half your packs voltage each. Then run two leds. Maybe start your own thread and ask, I bet someone knows a compact solution

This takes 96v, whatever this is lol

yeah, i also dont really have a good background knowledge of electronics. i wish i had done more at school...but hey! this IS school :D

i seem to remember it was similiar to one you posted a link to before it dissappaered.


so please clarify- a cc cv led driver will give you adjustable brightness, but to get the facility of an on-the-fly adjustment dial, you need a pwm motor controller, cause it has a neat dial built into it for adjustment?
I used a cc regulator (qskj thingy) and got the least meltdowns but it was only on/off. If all you want is a main beam thats fine.

the one you have listed is a step up boost converter. this will be fine but you need a power source lower than the led.

If you could use the one you have shown but replace a blue pot for a larger one you could have remote adjustments. It was nice to have variable levels.

do all testing with a volt meter lol


I dont think pwm is good for leds when your drawing current from the pack with a motor randomly and cc is recommended anyway. I only used the pwm circuit as It was easy to hack the potentiometer and one of my battery sections was 30v. Some of them activated half power if you interrupted the middle wire etc.

PWM is fine for LEDs, as long as the frequency is high enough you don't see the blinking. ;) Most DC-DC converters use PWM to do their thing, anyway. Those that don't, using linear regulators, are just wasting all the unused power as heat and may require large heatsinks.

You can add a capacitor (or resistor-capacitor "RC filter") at the input to the LED to smooth it out if you like.
Cheers amberwolf. I could just find a point above flickering that wasnt blinding but it was a fine line and hard to set while riding lol.

what i meant was when i used pwm it dimmed badly when I gunned the motor
That means that the DC-DC doesn't use it's PWM set-control to set a voltage or current, it just uses it to set a duty cycle, so the output is simply always that percentage of it's input. Thus, if the motor pulls battery voltage down significantly during acceleration/etc., then the output of the DC-DC will go down as well.

If the DC-DC's set-control were instead able to set a particular voltage or current, then that wouldn't happen.

If you put a diode in series with the positive input to the DC-DC, and then a set of high-capacitance capacitors on the DC-DC side of that diode, it'll help smooth out those dimmings, as long as the capacitors can hold enough to last until the motor-caused battery-sag goes away.

But it'll also take up a significant amount of space, depending on how much capacitance you nead, and could end up being less space/power/etc efficient than just having a separate battery for the lights. ;)
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 :)