Well thanks to all. I was finally able to figure it out.
In the end it was a really fast calculation at the electronics store that helped out and it is starting to make sense. I learned to look at the package and determine the wattage from the ma rating. Most of the ones I have are 25ma which equates to 1/4 watt and if the voltage is 6v I subtract the 2.4v max and then a calculation is made ( I am still fuzzy on that) and I got 144 ohms. I installed them and I got this:
Question: on the back of my led the package says forward current 25ma which I believe I understand as the 1/4 watt, the max voltage is 2.4v so it seems that the only calculation need is the ohms. Is that correct.
Question: Based on the calculations below
From John
E = I * R
E = Electromotive Force; in other words, Volts.
I = Current; measured in Amperes, also called Amps.
R = Resistance, measured in Ohms
So, Ohm's Law establishes the relationship between Volts, Amps, & Ohms.
If you have a 6V power supply, & you want to limit current to 25 mA (milli-Amps, or 1000ths of 1 Amp; 0.025A), then what resistance do you need?
From Ohm's Law we know that E = I * R. Our value for E is 6 (Volts). Our value for I is 0.025. We need to solve for R.
6V = 0.025A * R
R = 6 / 0.025
R = 240, or 240 Ohms. Many times, a "ballpark value" is all you need. Also, it's often a good idea to "pad" it a little, for safety.
This makes sense but when I went to: http://www.quickar.com/noqbestledcalc.htm, and used the single led it said to use 144 ohms. The guy at the electronics store told me to use 144 ohms. How do that arrive at that number given that I have a 6v battery, 2.4v max, and 25ma current?
Thanks for all the help as I really wanted to light my ship. I got a blinking green light for the bow and a blinking red light for the stern (just have to figure out how to mount it so it wont get shot off).
I really appreciate all the help.
Thanks to all!