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I have a 12v LED which i want to install on my motorcycle. And i am not getting a proper way to install it directly because the voltage is not constant but fluctuating and i lost some of my LEDS like this. Answered

How to use 12v led on a motorcycle's fluctuating 12v dc source.

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adhith94 (author)2018-04-12

As Jack A Lopez said Leds are usually powered with constant current mode. they are very sensitive to current levels than the rated current limits and could fail at these levels. resistors are usually used in series to limit the current from the source and works well for smaller leds but as the current requirements is more like in your led, the loss of power through the resistors will be more . You also meant about the fluctuating 12v dc source, so having a constant current constant voltage driver to power your led will be a good option. But for it to work also you must need to know the safe working current of the led. Check for its part no. and get the appropriate datasheet to know the working current.

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Yonatan24 (author)2018-04-02

Use a step down converter to step down the voltage to under 12V, and get a big heatsink that won't even get hot. Then you're safe.

I wouldn't bother with constant current, just make sure to use thermal paste that you can get on eBay for really cheap. See more explanations here: https://www.instructables.com/id/SpectrumLED-V20-t...

Also, keep in mind these are cheap LED's and if I were riding a motorcycle I wouldn't want to depend on them to keep me alive.

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Yonatan24 (author)Yonatan242018-04-02

What happened to the LED BTW? Is it burnt?

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Jack A Lopez (author)2018-04-02

I suggest finding, or building, a regulator, for to supply constant current to this LED. That is the usual method for driving LEDs.

I mean, I am guessing this, what we are calling LED ( more likely it is an LED module, a group of LEDs on the same die, since its forward voltage drop is around 12 volts) draws more current than would be convenient for the usual, easy trick, of just putting a resistor in series with it.

Actually, if you know how much current you want this LED module to draw, it might be worthwhile to do the math for calculating a resistor to go in series with it, and also the math for how much power that resistor would dissipate. Also calculate how much power the LED module dissipates.

Although the math might be funny, if the battery voltage is very close to the forward drop across the LED module, like if both are close to 12 volts. If the difference between these is close to zero, that is just going to suggest the resistor between them should have close to zero resistance, which is confusing. It might be that you have to pick a resistor corresponding to the highest experienced battery voltage, just to protect the LED from overcurrent, and on occasions when the battery voltage is not that high, the result is the LED module is dim, not bright, from low current.

Also, maybe the LED module wants a heat sink, at that level of dissipated power. A heat sink for the LED module might help, if you do not already have one, and if you seem to be destroying LEDs by overheating them.

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Toga_Dan (author)2018-04-02

is the voltage regulator on the bike not workin right?

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