Voltage drop
Thread Starter
Instructor
Joined: Sep 2009
Posts: 118
Likes: 10
From: Deltona Fl
Voltage drop
I have an 08 base convertible automatic.I replaced the battery about
6 months ago. For some reason I the dash to show the voltage. The car
started out with 14.2 and went down to 13.5 after about a 45 minute
trip. Is that something I should be worried about? Thanks
6 months ago. For some reason I the dash to show the voltage. The car
started out with 14.2 and went down to 13.5 after about a 45 minute
trip. Is that something I should be worried about? Thanks
Racer
Joined: Oct 2013
Posts: 420
Likes: 63
From: Earth
My '05 does this. Very annoying. Starts out at 14.3 but drops to mid 13's or lower after driving on the weekends running errands. If I put the AC on, it goes even lower. AND, if I let the clutch out a little too quickly without giving it enough gas, it bogs down and drops to 11.1.
I can't tell if it's just a garbage OEM alternator, bad regulator or some other issue. But most people here tend to state as Unreal did above, this is par for the course on this car.
My '95 Z28 never did this. Sure, a different engine and components but still.....
I can't tell if it's just a garbage OEM alternator, bad regulator or some other issue. But most people here tend to state as Unreal did above, this is par for the course on this car.
My '95 Z28 never did this. Sure, a different engine and components but still.....
Melting Slicks
Joined: Jun 2006
Posts: 2,484
Likes: 261
From: Miami Florida
Racer
Joined: Oct 2013
Posts: 420
Likes: 63
From: Earth
*Off Topic* I've already spent money on lots of stupid things that should not have broken on this car and indeed just spent almost $600 on a rear view mirror because the pot-metal fitting the bracket ball snaps into broke several tabs recently making the entire mirror useless. That internal piece is not replaceable either. Thanks GM for designing an expensive failure right in to the car! *End Off Topic*
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,341
From: Gilbert AZ
It meets there design spec and keeps voltage over 12.5, but GM alternators don't like heat and drop. I noticed my car runs much better with a constant 14.7V. Everything seems happier than dropping when hot.
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Le Mans Master
Joined: Apr 2011
Posts: 7,820
Likes: 408
From: Montreal
St. Jude Donor '13
Originally Posted by Unreal
It meets there design spec and keeps voltage over 12.5, but GM alternators don't like heat and drop. I noticed my car runs much better with a constant 14.7V. Everything seems happier than dropping when hot.
Melting Slicks
Joined: Jul 2010
Posts: 2,999
Likes: 242
From: Surprise, Az
Jay,
13.5vdc is a normal voltage and means you are less prone to cooking the battery. The 14.2 you saw is a bulk charge to the battery, after that the regulator can taper it off so the alternator isn't working as hard, and is actually close to the ideal float voltage of 13.2v. When the voltage is lower, the alternator is taking less horsepower to keep the system charged.
If you are concerned about it, I would make sure all of the ground and positive lead connections are dry and tight and leave it at that.
13.5vdc is a normal voltage and means you are less prone to cooking the battery. The 14.2 you saw is a bulk charge to the battery, after that the regulator can taper it off so the alternator isn't working as hard, and is actually close to the ideal float voltage of 13.2v. When the voltage is lower, the alternator is taking less horsepower to keep the system charged.
If you are concerned about it, I would make sure all of the ground and positive lead connections are dry and tight and leave it at that.