Went out to the car this morning and it was 47 degrees fahrenheit in the garage. Car had been left overnight in the garage.

Voltage before starting the car: 12.17v

Voltage while cranking: 8.5v (it started up right away but that's the lowest voltage I saw)

Voltage once running AT IDLE: 13.0v (only measured it from engine start until 20 seconds later. Assuming it didn't go higher than that later on. Did not rev engine above idle at all.)

Any thoughts? I know the voltage when running seems a bit low (shouldn't it be 14v?) but the alternator is old.. it doesn't need to be replaced yet though does it?

My conclusion is that the battery sucks.. 12.17v sounds really low to me for a battery that "should" be fully charged. Car was driven 30 minutes last night before I put it in the garage, so it should have been "fully charged" when I put the car away for the night. The cranking voltage sounds really really low to me too!

Should I start by getting a new battery under warranty or do I have an alternator issue? Or something else?

Thanks!

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