Will I fry an LED doing this and other questions

Hosfelt has 8000mcd red 5mm leds that use 2v. If I use one for a 2AA mag mod, will I cook the led? Is this a good choice? Also, the 5600 whites call for more than 3v, is underdriving a problem?
Finally, is there enough room to use a 10mm led in a mag or Brinkmann??

anyone?

Geoff, and LED rated for 2v will probably work at 3, but it'll be seriously overdriven and will get hot, shortening life, and changing the color output as well. A 5600 mcd nichia will run on 2 AA's, but be quite dim. It's not worth the effort really, as cmg infinity's and Arc AAA's are rather cheap. There's lots of historics on changing the minimags w/ nichias, though you may have to search further back since the LS craze hit.

I think you can get some other red led's that are pretty bright and will work at 3V ok. For example, if you have a Photon keychain light, you might try that led. Dunno if this is being overdriven and is ok in this application only b/c the battery is so small, etc.

You might also want to consider using 2 AA nimh instead of alkaline...2.4V instead of 3V.

This should do the trick.

Remember that LEDs are non linear devices. They operate on current not voltage. You should include a current limiting resister in series with the LED for best results (unless using a constant current source ). For example, if you wanted approx 20mA, you would use (3V - 2V)/20mA = 50 Ohms.

In some instances, you can rely on the internal resistance of the cells to limit the current. Unfortunately, the internal resistance of alkalines is very low and thus you will kill your LED (or at least greatly reduce it's useful life).