i intend to mount the MPCB onto this 100mm radiator to ensure proper heat dissipation.
As for the driver, my friend will build it, FET based with Moonlight, Turbo and Strobe modes, each on a dedicated button. My question is, how much current can i feed the Leds for maximum output, considering the massive radiator behind it and at what voltage would you recommend? I was planing to use 2 high discharge 18650, in parallel. Would you recommend otherwise?
Thank you for taking your time to help me in my project.
from what i saw on this thread: https://budgetlightforum.com/t/-/34094 the optimal voltage and amp draw per led is 6.2 amp and 3.51 v… that would give me a total consumption of 24.8A at 3.51… so 2 18650 in parallel, each having a > 20A discharge should be the final solution to my problem. And i suppose i should limit the voltage, and amps will flow as the leds consume, right?
Please correct me if i am wrong, this is my first build of this kind, your expertise is highly appreciated.
What you ask does not entirely make sense, or at least it is not detailed clearly.
Like for example what exact is that driver, a FET driver, is that a linear driver or a direct drive FET?
You cannot feed current to the LED, the LED draws current,
You want to limit current the LEDs draw with resistors like with ultra low current LEDs?
These Nichia LED can potentially die at high currents in time.
Is that gonna be a flashlight? Off-road light? Something else? I can’t imagine having a flashlight with a big honkin’ heatsink like that sticking out from the front.
There’s maximum light and reasonable maximum light. Lumens vs amps is an inverted parabola, highly dependent on the heatsink, airflow (or other cooling), ambient temperatures, a myriad of other factors. You’d have to determine this empirically (ie, build it and test it).
Light falloff due to heat means you can dump, say, 50% more current through the LED, and get only 10% more output. Is it worth it? 10% probably wouldn’t even be able to be spotted as an A/B test, flicking back’n’forth between, say, 1000lm and 1100lm.
Also, past a certain point, more current means more heat and less light.
Further, Nichias don’t take too well to excessive heat, and will go pouf easily.
the info regarding the amps feed is taken after a highly appreciated(from the comments he had) thread that posted a study of this exact led. I mentioned the link in my seccond post.
The light will be mounted onto a bike, and i have a separate space for batteries and driver/switches, so i only need to expose the radiator, led and optics. That is why this is not like any other flashlight, since it does not have to get a body that includes only 1/2 switches and batteries and driver. Only strobe will use the maximum light output, the other modes will be limited.
Regarding your sarcastic last words, i would like to tell you that I have no experience with leds, i am barely beginning to understand what i should search for and what to read, that is why i asked for help, if i already knew how to make it i would just expose the final project. So NO, not enough Info…
What i asked is how can i get the most of this LED PCB, how should i design the driver (so i know what to ask my friend to build, he said he has no experience in led drivers), a few directions in that way…
If you got no experience with LEDs how about drive em to their specs in datasheets?
Just get a normal 1000 Lumens flashlight and see that is already to bright for a bike
I see no use for a bike headlight that is pushing out 4000 Lumens with a standard optic,
you ruin your night vision if you have to look left or right you see nothing because your eyes are not adapted
you get probably hit by a car which driver you blinded and have to pay for the damage on his car
Guys, there is no use for so many things, and we still buy/do them just to push the limits. Is there no one that can give me some tech specs about how should the driver be instead of trying to see if there is a use for my project or not? I just read thread where a guy created a 6mm in diameter and 16mm in length flashlight. What is the use for that?
If you do not want to help or just do not know what to say, do not come with posts like this:
“you get probably hit by a car which driver you blinded and have to pay for the damage on his car”
WTF?
Please Stop judging and presuming possible scenarios regarding the use and help the build.
Nobody was born with any experience whatsoever, all of you started from scratch, if you are willing to lend a hand and help me out by sharing some of your experience, just do it!
Doubt it, unless you’d have “infinite heatsinking”. All 4 emitters would be on the same mcpcb, needing 4× the cooling capacity to keep each LED cool to the same degree.
You’d get comparable results for ¼ the current to each one, so that total power is equal. Difference being current-density through each LED is only ¼th as well, letting them be more efficient and throw more light for the same input total power.
So you suggest to feed them just 6 amps in total? The heatsink is quite big, comparing to what flashlights can dissipate, and on full power it will run just for 20~30 secs max, followed by a minute minimum pause. and as fast as i see it going to hot to touch i will let it cool down. I just want to make a mode that can squeeze the maximum output it can give for a few seconds.
I also read a post saying that if you attach the carclo lens with optical glue to the leds i would get more lumens in the right direction.
The heatsink is not big, at 6 amps per led you need to dissipate 60W of heat to the air. Outside on a bike at some speed if it is cold there may be enough airflow to do that with this radiator, but in all other circumstances it is way too small, perhaps good for 10W. But you mention already that you will only use it for 30 seconds on full power.
I’m not an expert on drivers but I would not bother to have a complete new driver built by your friend because driving a parallel quad on two parallel 18650 cells is a very common situation, there are cheap drivers around for that, I like the BLF-A6 driver (a FET based direct driver with regulation on the lower modes), it is about 5 dollar at Banggood. I think you will just about get the 24 A with 2 charged HG2 cells on this quad, if you take care to keep the resistance in the electrical circuitry low.
the BLF-A6 driver would be great if i could find a way to take 3 separate switched out of it for 3 separate modes. I hate cycling trough modes, and since i am not constraint by size/shape, i would like a button for max strobe, one for continuous high, and one for low.
Do you or anyone else know a source of information (a thread/guide) on how to build a LED driver?
regarding the heatsink, the 50mm long is advertised as enough for 3~9w… since i will be using the 100mm, it should be good for ~18w. and since i do not intend to forget the light on max for an hour, i think it will be more than enough of a few bursts from time to time.
as for the resistance in the circuit, i will use 16awg wires and the batteries will be soldered trough their tabs to them, so minimal resistance will be acquired.
Its very dificult to dissipate 60w of heat. I see the heatsink you linked and its for max 10w.
So, you say that will be instaled in a Bike (good airflow at least moving) , with this heatsink i not recomend you more than 25-30W with this conditions.
My recomendation with this led is:
2amps per led—- 8amps in total—- 2700 led lumens (aprox)
My bad, i not read that you will use the 100mm one that will be ok for 18-20w. So with good airflow maybe will be ok with the 60w. But thats too close to the limit. 40-50w its more safe and probably the down in lumens will be very little
regarding the driver build, or modifying an existing one for separate modes on separate switches, can someone give me a clue on what should i do/adapt/build?
