Alright I plan on using these 3000mcd leds for my climate control

http://www.superbrightleds.com/leds/b3023_specs.htm

these say they run a typical 3.5v forward voltage at continuous current of 20 ma. If I wire them in parallel, it requires around a 106 ohm resistor but the closest is 120 ohm, would this work ok and be bright enough?

OR could I get away with using a 100 ohm resistor or would it be too much for the 4 volt max handling?

 

100ohm and 106ohm isnt much difference since resistors are not 100% accurate in the first place. If in doubt, Its better add more resistance than less.

 

how many are you wiring together in parallel?