Maybe Madman can help me out, but anyone with some car knowledge is welcome to answer as well...
Car has been having a bit of an issue starting for the last week. I chalked it up to being very cold in the mornings. One day, would not start. Dead battery. Battery is less than 2 years old. Other symptoms, I upgraded my car stereo about 5 years ago... New head unit and two amps totaling about 1500 watts. When I installed the stereo, I upgraded the "big three." I've never had any issues with the stereo until this week. Get to a stop light, one of the amps would cut out. Hit the gas and all is well again.
At this point I'm thinking the alternator is going out. Car (Honda Civic) will be 8 years old next month. I broke out the voltmeter and tested the battery with the car off. Tested at ~12.5 V. Started the engine with no accessories on and tested at ~14.2. Turned on head lights, fans, rear defroster and stereo and tested again, this time at ~11.5. Side note: turning off the stereo didn't bring up the voltage. Am I correct in thinking the alternator is going out (at least one phase)?