

Hay una web que lo calcula
http://led.linear1.org/led.wiz
Por ejemplo, para 13.5 voltios de la batería, tensión de diodo de 3,3v corriente de 20mA (típica de los diodos) y 4 leds, te propone ponerlos en serie y una R de 18 ohmios.
Source voltage

diode forward voltage

diode forward current (mA)

number of LEDs in your array
View output as: ASCII schematic wiring diagram

help with resistor color codes
'Aquí saldría el conexionado'
Solution 0: 4 x 1 array uses 4 LEDs exactly
R = 18 ohmsThe wizard says: In solution 0:
- each 18 ohm resistor dissipates 7.2 mW
- the wizard says the color code for 18 is brown grey black
- the wizard thinks 1/4W resistors are fine for your application

- together, all resistors dissipate 7.2 mW
- together, the diodes dissipate 264 mW
- total power dissipated by the array is 271.2 mW
- the array draws current of 20 mA from the source.