thanks for the reply
I have tried the LED in place at 3V and it wont be bright enough but at 6 it is *just* bright enough and at 9V is spot on (using small 3v watch batteries)
but wiring it directly to the cars 12v burnt it out almost straight away
does the amount of increased current decrease the life of the LED on a linear scale ?
eg 3v - life = 50,000 hours
6v - 25,000 hours
if current gives higher output what does the increased voltage do ?