New alternator with problem

[maybe2fast]

I just put in a remanufactered alternator and battery and a new belt and had help readjusting the ditant cable. anyway the alternator and battery looked fine on the VAT 40 but at about 5000 RPM and anything above the battery light will come on and blink and the lights will dim but as soon as the R's drop every thing will return to perfect. Could the new belt be slipping on the new pulley because it has paint on it? other than that I am puzzled! I was only in that R range because I was testing the shifting after the adjustments