properly calculating battery voltage and resistors.

[dj2rbo]

Hello. One thing I'm confused about is finding the right value for voltage when trying to find out which resistor to use. What I mean is nimh batteries have 1.4 something when fully charged. But everyone uses 1.2 volts for the equation like the store chart. I understand that it may not stay at 1.4 for a long time, but at the same token at 1.2 the power is very weak. another thing is .2 volts might not be alot but when multiplied, using red amber lux you end up risking destroying it. Anyway am I crazy or am I making a valid point? How do you guys calculate it??

[theJUDGE]

if you google resistor calculator you should be able to find one that lets you enter in the voltage you are using. like the one i found here:
http://led.linear1.org/1led.wiz
it is for a single led. you enter the voltage you are using, the forward voltage of led from given specs, and the forward current needed in Miliamps.
im sure you already knew all this, but i would say calculate based on the specs of your voltage that you were given. if the place you bought it from says 1.4 volts per nimh battery, then i would probably rely on that. im not very tech savy, but if you figured out the resistor to use for a higher voltage source, the resistor it tells you to use would be able to properly handle the suspected higher voltage you mention (1.4 volt nimhs) as well as the lower (1.2 volt nimhs).