I have a digital voltmeter that plugs into the cigar lighter; cost less than $20 thru amazon. At idle, the voltage is about 12.2 and the ammeter is showing a slight discharge. At fast idle, the voltage is over 13 volts and the ammeter is showing a slight charge. Speed up and the voltage goes over 14 volts.
I think 55shaker is correct - charging system needs to be looked at. There are instructions posted in the forums here on how to do it.
