New Voltage

I'm just curious, what effect does the rectified DC current have on the lighting? I don't notice any flickering or change in lighting intensity. Will the bulbs wear out faster? What are the down falls of this if you are only powering headlights? I will also be adding electric fans and plan to use the alt as a power source also, will this current cause negative effects for the fan motors? How would one wire in the stereo type capacitor to act as a buffer?