Battery voltage
Thread Starter
2nd Gear
Joined: Sep 2012
Posts: 2
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Battery voltage
hi all this is my first corvette 2015 shark gray 2lt z51 yesterday took her out for drive volt meter at start up read 14.8 volts about half hour in to my drive voltage dropped to 12.9 and stay there went into a store came back out started car volts back to 14.8 on ride home same thing happend 12.9 is this normal in the c7 or should i have it check out at dealer thank for any help in this matter
Racer
Joined: Jun 1999
Posts: 407
Likes: 91
From: Chandler Arizona
It sounds like your battery is getting weak (your voltage is computer controlled will depend on the what state of charge the battery is in, ). Is your car driven daily or weekly? If weekly I would suggest you get a battery maintainer for it. In any case I would get the current battery load tested to see what condition it is in.
Tom
Tom
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
The system is programmed to vary the charging rates to help extend the battery life. Old systems would just maintain around a14.7v charging rate even in a battery in good condition, not on current cars. I have been driving on the interstate so the battery is as fully charged as it can get, and the alternator will drop down and charge at 12.8v for awhile. What are seeing is completely normal operation.
I have also seen it jump up to 15V+ and charge for awhile.
I have also seen it jump up to 15V+ and charge for awhile.
Last edited by TEXHAWK0; Sep 16, 2017 at 11:50 AM.
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E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,106
Likes: 12,446
From: NE South Carolina
Yep, normal as others have said.
Like many other things in the C7 it's now controlled by computer to save energy! You'll find the same thing with oil pressure!
The C7 uses a "variable volume oil pump," to reduce energy waist. The computer uses an algorithm that allows lower volume to flow through the pump saving energy when it's not needed! It's not the old spring limiting bypass, the C7 literally changes the pump configuration so it pumps less it does not just recirculate it around the pump. When cruising you'll see the pressure drop.
Like many other things in the C7 it's now controlled by computer to save energy! You'll find the same thing with oil pressure!
The C7 uses a "variable volume oil pump," to reduce energy waist. The computer uses an algorithm that allows lower volume to flow through the pump saving energy when it's not needed! It's not the old spring limiting bypass, the C7 literally changes the pump configuration so it pumps less it does not just recirculate it around the pump. When cruising you'll see the pressure drop.
Le Mans Master
Joined: Oct 2005
Posts: 7,002
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Modern cars have "Battery Management" systems.
An alternator has a set point now (computer controlled) and when the battery drops below that point the alternator kicks on and brings up the voltage. Once the voltage reaches a higher point the alternator turns off. There are also special times when the alternator always runs (like on a cold start).
An alternator has a set point now (computer controlled) and when the battery drops below that point the alternator kicks on and brings up the voltage. Once the voltage reaches a higher point the alternator turns off. There are also special times when the alternator always runs (like on a cold start).
Burning Brakes
Joined: Mar 2013
Posts: 1,188
Likes: 239
From: Colorado
It surprised me too, on my '18. Posted on the Forum, and got the same great answers. In the "old" days, like my '13, charge was always 14-14.5. With the computer control, probably will aid in battery life as a side benefit.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,106
Likes: 12,446
From: NE South Carolina
^^^
Not sure it's a help for battery life but it helps GM meet their average corporate mpg goal!
If you haven't watched the oil pressure get very low in a step function, read post #10. Same reason every 0.1 helps GM!
Why not, no harm.
Not sure it's a help for battery life but it helps GM meet their average corporate mpg goal!
If you haven't watched the oil pressure get very low in a step function, read post #10. Same reason every 0.1 helps GM!
Why not, no harm.
Last edited by JerryU; Sep 17, 2017 at 01:40 PM.
Le Mans Master
Joined: Oct 2005
Posts: 7,002
Likes: 2,679
It's partly for MPG, but also to control load. The BCM will load shed some things while the alternator is kicking on. Usually it is so short you don't notice. But things like EPS take a LOT of current so they need to manage the electrical system now unlike in the old days when your biggest worry was cold start cranking amps.