Custom LED Application - Automotive

I’m completely uninitiated into this world but I want to make some blinkers/turn signal and need some help. I understand I will need the LED, then a resistor wired in, and possibly a heat-sink.

So my plan is to buy this (or similar) LED and then by using this calculator I will need a 27 ohm resistor as this will be running off a 12v motorcycle supply. This is the resistor I will use, with an aluminum heatsink. This will then be wired to the standard blinker connections but an electronic (as opposed to mechanical) relay will be used to make it flash.

For the calculator I input 3.3v (based on a 3.0-3.9 operating range), 12v, and 350mA based on the listed specs.

Will that work in theory? Heat management is a different issue altogether and not a concern yet. It will be blinking for short periods and not over-driven so it should be within sensible heat ranges. I haven’t decided on an exact LED yet.

Edited post, have new questions. Thanks :slight_smile:

I honestly don’t know the answers. However this seems a complex way of getting LEDs working on a car. Can you not just buy a suitable LED build to fit the stock holder?

This is what I’ve done on my 35 year old Land Rover and my 37 year old Triumph.

Sorry this is a custom application for a custom motorcycle. The housing the LED will fit in in only 12mm wide so you don’t have the advantage of a big plastic lens for light dispersion. To compensate I have to put a small but very bright LED with a small lens of some sort. Any purpose-built automotive LED globe is not as bright because it’s designed to work within the housing.

Can anyone see any problems with this setup? XP-G LED bare-emitter will be attached to a metal heatsink via some thermal adhesive. I elected to use the potentiometer buckpuck because I’m not sure what sort of brightness would be suitable so controlling the amps would be great.

-Buckpuck is here
-Light will be flashing at 1hz approx
-How much heat is produced @ 1amp?
-What is a safe current that will keep it running cool and reliable?
-Am I right in thinking that this buckpuck adjusts current and thus brightness?