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Barbarossa

Jan 4, 2024
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Hello,

I have this LED headlight I'd like to install on my motorbike, and I feel uncomfortable putting power on this LED.

So, any advice would be great.

I see a ceramic capacitor and an LED. I always thought an LED needs a resistor as well.

As I don't have the original bike that uses this headlight (it's from a KTM Duke 390 2017), I don't know what voltage I need to supply the module with, and I don't know if I'm missing the resistor.

Is it an option to start putting voltage on the board with a voltage regulator? I am afraid of blowing up the board.

Thanks in advance.

Best regards, Bart
 

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Martaine2005

May 12, 2015
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That LED might have built in resistors.
But not knowing the voltage of the KTM, I would start at 6V. Some motorbikes are 6V, then try 12V if it’s not very bright.
 

Barbarossa

Jan 4, 2024
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If I wanted specs from a headlight of a Chevy truck I wouldn't go to the Ford truck forum.
I hope this helps.
Hello, I understand your reply. I have been gathering information for a few months now. The problem is, I'm talking about the inside of the headlight. Not much information is found online. KTM is not sharing this, except for some Indian people I found who have opened the headlight. I didn't find anybody on a KTM forum that has knowledge of circuit boards. In the end, I found a headlight, and I bit the bullet and started the investigation with a real unit because I couldn't find sufficient information about the internal board online before buying the unit. That's why I ended up here. Now I have the unit; I just want to get some feedback before I break my "new" headlight. All feedback is welcome, so thank you for the reply!"
 

Delta Prime

Jul 29, 2020
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Can you get inside of it take some photos perhaps without destroying it.
 

Barbarossa

Jan 4, 2024
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Can you get inside of it take some photos perhaps without destroying it.
Yes, I have already opened it.

The low beam modules are both exactly the same, like in picture one. The high beam modules are a little bit different; you can see that one module has 4 connections, so I guess DC+ and DC-, and the M+1 and N+1 go to the second high beam module. M+1 and N+1 pass through the first module to get power in the second module.

The modules don't look like they have a lot of components on them, so I was hoping to get this clarified without having the original schematics.

thank you for the time
 

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Barbarossa

Jan 4, 2024
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Hello,

I have limited experience with PCBs and LEDs, but based on what I've found online, the Low Beam LED appears to be a 15-watt LED. I've measured no resistance between the test points on the PCB and the LED or the connector, leading me to assume there is no resistor currently in place.

According to my calculations, would a 10-ohm resistor be needed for a 12-volt setup in this case? Are my assumptions plausible?
I have no clue what the ceramic capacitor is doing on it...

Thank you in advance for your assistance.

Best regards, Bart
 

kellys_eye

Jun 25, 2010
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I would suggest that the LED isn't driven directly but from a CC (constant current) source situated elsewhere. It may even be PWM (pulse width modulated) as the inclusion of the capacitor is inevitably to bypass/decouple spurious noise on the power lines.

No way is that a 15W LED (no heatsink for a start) and given it says 'low beam' and for filament bulbs that commonly relates to a 5W bulb, the LED equivalent would be under 1W.
 

Barbarossa

Jan 4, 2024
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Hello,
Thank you for the reply.
A H4 halogen low Beam light is 55 watt
it has a heatsink
could you please tell me more about how i can power this in the correct way
 

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kellys_eye

Jun 25, 2010
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If the LEDs have no resistors then they MUST have another controller module associated with them. If they could be run using 'just' resistors then, for cost purposes alone, they would be. Given that they aren't then although they might work using a dropper resistor it will be (a) inefficient and (b) potentially harmful (short life etc).

LEDs are most safely run as CC devices - resistors are a poor substitute unless running LEDs of 'insignificant' power i.e. in the mW range as most 'power indicator i.e. on-off' LEDs are.
 

Martaine2005

May 12, 2015
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I agree. These must be ECU controlled and therefore constant current controlled also.
Nothing to say that you can’t control the current if using in a different environment. A resistor would then be the appropriate component.

Martin
 

Barbarossa

Jan 4, 2024
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I agree. These must be ECU controlled and therefore constant current controlled also.
Nothing to say that you can’t control the current if using in a different environment. A resistor would then be the appropriate component.

Martin
Thank you for the reply. I followed your advice. I started with 6V, and with my stepdown voltage regulator, I got to 8 volts, and the LEDs are producing a lot of light.

I kept track of the amps and heat, and it was stable for approximately 1 hour, so it doesn't seem like they overheat.

Can i keep this setup will it be reliable? i use this step down convertor.

When monitoring the amps of the lowbeam, I don't get more than 50mA drawn by the LED. According to a datasheet from a LED that looks a lot like mine, it could draw 1.5 amps. So maybe I'm just looking at the wrong datasheet. Or maybe with PWM and a higher voltage, you could get more light out of it; I don't know much about this stuff...

But the light created with my current setup right now is more than enough for me. I just need to know if the LEDs will last a long time before I glue the headlight again.

Thanks in advance.

Best regards,

Bart
 

Harald Kapp

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Are you aware that by this modification of the headlight you may lose the approval to use the bike on official roads?
 
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