Voltage makes no difference, so long as its above a specific value for the LED. Everything is determined by the resistor used in series with the LED. You're not giving the resistor enough voltage, so its not giving the LED enough current.
Either switch out the resistor for a smaller one, or give it the rated voltage for the resistance built into the fan. I've never seen an LED fan, so I don't know how easy it would be to get at the leds. Ideally you could just disconnect the resistor-diode circuit from the fan and plug it into a 12v source. Otherwise you could buy proper resistors, desolder the included ones, and then solder in the new ones. Of course if you did this and plugged the fan back into a 12v line, you could burn out the LEDs.
If you wire LEDs without a resistor (put 4 in series across the 12v line) they'll probably pop in a second or so. Internally each LED has ~0 resistance once its biased, so a resistor is required to keep them from pulling a few amps and melting.
|