You're misinformed about losing electrical power. Everything on the vehicle is powered by the battery. The alternator keeps the battery charged, and when it fails, the battery will continue to run the electrical system for as much as an hour, depending on how many things you have turned on. With a charging system failure, you'll see the voltmeter on the dash drop from around 14 volts to around 12 volts, the head lights will dim, and the heater fan will slow down.
The most common cause of an intermittently-dead charging system is worn brushes inside the alternator. The assembly costs around $15.00, but most people just replace the entire alternator after diagnosis proves it's not working.
Given the low miles and the noise, check the idler pulleys for the serpentine belt first, and check if that belt is tight. A loose belt will allow the alternator pulley to slip and the alternator will stop charging. That will be worse if it's raining.
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Sunday, July 27th, 2014 AT 8:40 PM