Single LEDs

Hey guys, I recently ordered some of those single LEDs without resistors from Hong Kong over ebay. I got them and decided to try them out. I got a 9 volt battery to test them. So it turns out that one kind of 9 volt makes the LEDs a dark blue and a different brand makes that same led a lighter blue. When the LED runs off the brand 9 volt that makes it a lighter blue it gets hot to the touch and burns out. Can anyone explain what will happen when I wire these up inside my car to the battery, after I attach the resistors. Also I'm assuming I attach the resistors to the positive wire correct? Thanks guys.

well, your problem is that i dont know of any LEDs that run on 9v, highest i've heard of is around 4 volts so if you hook a 4v LED to a 9v battery....POOF

i have a program to heap with the calculation of the resistors u need plus the resistor can go on either positive or negative, it is easier to stick to the same one to make the install easier, if u want a copy of the program forward ur email to me and i'll send a copy, btw it is rather smallmodest yet effective... ECLIPSE 12", Venom 8"x2, Focal 5 1/2" comp.,Response amps x2 (580WRMS total @ 4Ohms), Pioneer TFT + DVD, good for 148.7dB