# 2 3.2v LED in series on 12v source

hi i am planning to install two small white light LED on my car as parking lights.

so basically i am using the reflector along woth LEDs from a torch that uses 3 AA cells(4.5v), the power of LED in manual is 3.2 V and the 1/2or .5W, as we know

V=I*R which Implies I=V/R and R=V/I

and P=V*I, by following these equations i get 154ohm resistance to be used but i used two individual resistors of 60 ohms with each LED, so my question is will it work (well ofcourse its working as of now but for longer durations like 2-3 hours continous working and also with charging system engaged, i guess the power source will change from 12v to 13.5 V.

any help will be appreciated.

• Does the datasheet not specify forward current? Aug 18, 2013 at 13:52
• unfortunately no info on forward current is given! and sorry i got the wrong calculation page , it turns out the 154 ohm for resistance and the resistors used are 60 ohm each! Aug 18, 2013 at 14:00
• Please provide a link to the datasheet. Aug 18, 2013 at 14:00
• Hi Ignacio, here is all the info: LED type 3.2v P=1/2W 40lumens ultra bright LED, so usinf these i get v=12v-3.2v=8.8v, and I=P/V putting values I =.5/8.8=.057, And R=V/I putting values R= 8.8/.057= 154.38 ohms. this is all the info hope it will help. Aug 18, 2013 at 14:15