Good answer by Rick.
But I may also suggest that you try wiring two LEDs in series, and power the two in series by 12V, so that, each one gets 6V.
Brightness might be a bit less as with 8.4V, but, good for the service life of the LEDs and no energy wastage in the resistors.
You need to know the required LED current. I would guess it is about 20 mA. Select a resistor that will provide a nominal 20 mA at the "average" LED voltage. This would be (12-6.6)/.02=270 ohms.
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Put two in series and make sure to follow its polarity,then power them directly with 12V.
As stated in the question, the Leds I want to wire in are supposed to run within 5 to 8.4 volts. Car/Motorcycle alternators put out 12v. How can I properly wire the led's in?
