I was wondering how consistent the vf is? My plans is to connect a number of leds in series, lets say 15 rebels in a string. This is fed by a 54vdc regulator at 650ma allowing 3.6v for each led. Do you think some leds will have a bigger or smaller vf than others in this string? I havent been experimenting with leds that much yet and have not much practical experience.
What problems could I encounter?