Tonight was the first night that I've needed to use my rear defroster in months. I turned on my headlights and heater and then as I went to leave the driveway I flipped on the defroster. All my lights dimmed out and my volts started dropping. I turned off the defroster and everything returned to normal. I turned the car off but put the key in the ON position then turned the defroster on. It starts draining my battery.

Any clue as to whats wrong? The battery and alternator are less than a month old.

 

You have a short in your defroster circuit. Your "hot" is touching your ground. Most likely behind the dash switch the hot wire is grounding to the dash. Check all the wiring. Has nothing to do with your new alternator.