Battery crapping out??

Great warm weather here today so I drove the car to work. Ran fine the whole time but I did notice the battery voltage showing around 13.5. Didn't think much of it and went to work. On my way home I paid much more attention and it was still low. At times when at idle at stop lights it would go down as low as 12.3v.
Car never died or hesitated had l thought at speed I should be around 14v. It would stay in the mid 12's. One interesting thing, if I was cruising along and let off gas completely to coast while in gear, it would jump up to 14+ volts. But as soon as I would touch the gas, it would start to drop.

Thoughts? Is the battery even a warranty item? Car has 2200 miles on it.

Battery is a warranty item. Not sure about the voltage variance though. I will say I would think more alternator than battery if there is an issue at all. Funny you mentioned the voltage. I happened to be playing with the gauge mode for the first time today and actually paid attention to all of the reading. Voltage ranged from low 13's to over 14's. I have 680 miles as of todays driving.

All these newfangled cars have "smart" alternator charging circuits, reduces
alternator drag under power, and charges while coasting, sounds normal.
Buy a CCA/voltage battery gauge on Amazon, around $50 or so, real handy
in measuring CCA, tells you true battery condition.

a fully charged battery with the engine off is 12.75 volts. Prior to computers alternators put out roughly 13.5 to 14.5 volts to maintain the battery at full charge. As stated above with computers they monitor the need to charge the battery resulting in lower voltage readings. I see nothing wrong with the readings you observed.

melwff said:

a fully charged battery with the engine off is 12.75 volts. Prior to computers alternators put out roughly 13.5 to 14.5 volts to maintain the battery at full charge. As stated above with computers they monitor the need to charge the battery resulting in lower voltage readings. I see nothing wrong with the readings you observed.

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+1 the readings are normal.

Thanks guys, guess I need to re-calibrate myself then!