Pretty sure I know the answer already, but I wanted to get some input from the forum. When I start my engine the voltage jumps up to ~14.2v, pretty normal. As I drive and the engine warms up it drops down to around 13v, and then fluctuates between 12.9v and 13.1v. Occasionally it will jump up to the mid 13's and then back down. Pretty sure it's the alternator dying, but just wanted to get some input.

 

Entirely normal
My Q70 does exactly the same thing
Your alternator is not dying
The voltage regulator is recharging your battery and reducing the voltage and charging rate as the battery reaches full charge.
If you want to see the actual charge level of your battery use a battery hydrometer to check the individual battery cells

Telcoman

Telcoman

 

Thanks for the input, this is the first car I've had that does this. My Jeep and my Focus sat right around 14v all the time.

 

It's always slightly moving. It's below 13 and above 14.5 that I start to wonder!

 

Yeah, above 14.5v and I would be wondering too

 

good to know. i freaked out a little when i saw my idling voltage at 13.1x today. thought the alt was toast but no dash lights, so started researching and people saying this is normal for this gen (mine's a 2007 sedan). thanks!

 

Pretty sure it's actually dying now. Voltage sits around 13v, and will sometimes drop to 12.5v for a minute or so, then back up to 13v. Also developed a bearing squeak. Lower pitch, not a high pitch like the idler pulleys I've had go bad.

 

I would disconnect the battery, disconnect the alternator wire, clean up the connection, then bolt it back together.

Might just be a corroded wire, free troubleshoot before you throw in a new/remanufactured alternator.

 

Battery is brand new, cleaned up the connections when I replaced it. Alternator was pulled when I changed the water pump and gallery gaskets and the nut looked almost brand new.

 

Mine made noise last summer so I swapped it.

A rebuilt alternator is cheaper than a tow.