I had a new, 130 amp alternator put on my 2005 Cobalt LS today with the 2.2L engine. Once it was installed the mechanic tested it and it's running high voltage, 15 amps loaded and unloaded. They're afraid that this could cause damage to the electrical system. I drove it to and from work and it runs fine. I had it tested by advance auto on the way home from work and they also tested high voltage (see attached image). Is this normal for a new alternator or is it faulty and should I habe gotten the 115 amp? I didn't know there was a difference and advance auto's web site said the 130 was an exact match for my car. Any and all advice would be helpful. Thanks.

 

How old is the battery? A faulty battery could affect system voltage. Other than that I'd warranty out the new alt since it is out of spec. Should be under 15.

 

I bought the battery in 2011. It tested fine when they tested the alternator. It was charged earlier as a result of it dying while driving it to the shop.