From a post I read on here it said it was fine to wire multiple leds in series, is this also the case if I have 2 boards with multiple leds.
Each led board is wired for 3 volts and if I go for the big ones ~50 amps, so rather than have to large power supplies (i have limited room) I wondered if i could put the 2 boards in series and run them at 6 volts from just one supply?
Many thanks
Short answer: Yes.
Long answer: Technically it’s actually better to wire in series, else in parallel you theoretically could get over current going through the one LED with lowest resistance.
In practice there are many flashlights that have 3 or 4 LEDs in parallel and it causes no issues.
Thankyou
To add to gravelmonkey’s comment: the resistance of the LEDs is often connected to the temperature of the emitter, so in order to avoid one of them drawing all the current it helps to thermally couple them as best you can. Lights that have multiple LEDs in parallel normally use a single MCPCB with them all soldered to it, in order that they stay close to the same temperature.
I was going to use the heads from 2 flashlights, just not the drivers, possibly something like a Convoy 3x21b or c. Each assembly will be in a seperste headlight (car) so will have fairly similar temps, although may not be identical, is this likely to be an issue, or is it just when wired in parallel they have to be close in temperature?
Thanks
I have found a picture of the LEDs in a 3x21b and they appear to have individual wires for each led, if this is the case, could these be wired in series and then run off a cc CV boost module to up my 12-24v to around 18v?
This would allow me to use much smaller driver/boost modules.
Thanks
In series you add voltage, parallel you add amps.
E.g you have 4x 3v LED in series, that need 2A, you need to drive the chain with 12V 2A.
If you put same LEDs in parallel, you need 3V 8A.
If you’re planning on driving these LEDs hard (you mention 50A in your original post), you’ll need a way to keep them cool, else they’ll destroy themselves. Modern flashlight drivers have a sensor to reduce current above a certain temperature, but this obviously means the driver and LED housing must be thermally connected.
I’ve not seen thermal sensors on LED MCPCB for a while, last was from LED4POWER 6 (?) years ago, who seems to have closed his shop.
Also, just to add, I don’t know what jurisdiction you’re in, but I doubt bolting 2x3X21B to your car is road legal, would be shame to go to the effort of building something then being told to remove them.
Yeah, sorry, slight change of plan, looking at something like 3x21b with 3x xhp70.3 LEDs now, initially was looking at 7* led or one really big led.
I am in UK, doubt it’s completely legal, but have previously had high beam led projector and currently led bulbs in the high beam reflector and hasn’t been an issue at test time. Maybe I need to think about making it easily reversible in case there is a problem, luckily my headlight lenses just clip on/off.
Slightly off my original topic, but I have read 6500k is brighter than 5000k, but in the photos and videos I see the bright centers of the beam tend to look like white and foggy more on the 6500k, is this the case in real life? And does it reduce the effectiveness as certainly looks like it in photos?
One last thing, I was looking at reflectors on Kaidomain and AliExpress, is there a way to tell how the beam will look? Or is it just a matter of finding videos/photos of lights with similar diameter/depth reflectors and LEDs and guessing?
Thanks
I forget the exact requirement for auxiliary lights, there is a basic requirement to not dazzle other road users though. There is no way I can see how a 3x21b would not cause dazzle, so you’d be limited to using these off-road or perhaps only on country lanes.
In my opinion, yes 6500K causes more backscatter than warmer tints, 5000K or even 4000K would be better.
Big reflector = more throw. Other than that if you’ve specific requirements you’ll have to do a bit of trial and error to find what you need.