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BrianG · 01.12.2011, 10:41 PM

You NEED a resistor in all cases. If you were to run, say, 2s lipo with LEDs with a Vf value of 3.2v each, the resistors are critical because the current would be 7.4v-(3.2v * 2)/0 ohms, which is mathematically infinite current.

If the LEDs are rated for 3.2v each, a string of 2 LEDs in series will require 6.4v. Running off 6v would technically be "ok" (sorta but not really), but relies on the fact that the voltage is not high enough to fully drive the LEDs and turn them into burnt silicon.

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BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	01.12.2011, 10:41 PM You NEED a resistor in all cases. If you were to run, say, 2s lipo with LEDs with a Vf value of 3.2v each, the resistors are critical because the current would be 7.4v-(3.2v * 2)/0 ohms, which is mathematically infinite current. If the LEDs are rated for 3.2v each, a string of 2 LEDs in series will require 6.4v. Running off 6v would technically be "ok" (sorta but not really), but relies on the fact that the voltage is not high enough to fully drive the LEDs and turn them into burnt silicon.