Battery Voltage fluctuate - Normal? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Goliath · 02-13-2011, 01:00 PM

It is normal to have battery voltage fluctuation from 12.0 - 14.5 volt while driving ? Thanks.

Eric Baker · 02-13-2011, 01:09 PM

It's normal for it to fluctuate a little, but it should always be above 13.5v.

Goliath · 02-13-2011, 01:20 PM

Thanks. While driving and idle, I see my battery voltage was at 12.0v for a while and didn't go up above 13.0v while driving at 30mph. After parked and turned off the engine, I couldn't restart the car. This intermit "can't start engine" is pissing me off. Left the car for 15 minutes and it start right back like nothing has happened.
Any idea?

Eric Baker · 02-13-2011, 08:20 PM

What's it doing when it won't start? Does it crank but not catch? Does it not crank but everything in the car is on? Could have a faulty battery or alternator. Anything done to the car electrically, like stereo or lighting?

turboguy327 · 02-13-2011, 08:56 PM

The BCM controls the alternators output through PWM. So the voltage will vary as the BCM sees fit for the given current draw. If your not using a lot of power the BCM will cut the alternator back. Supposedly it lasts longer that way. All the newer cars are like this.

fielderLS3 · 02-13-2011, 09:01 PM

Battery voltage can fluctuate on newer cars depending on how much power the car is using, how charged up the battery is, and even depending on when the computer thinks it is more or less energy efficient to charge or not to charge depending on driving conditions.

Goliath · 02-14-2011, 11:10 AM

Quote:

Originally Posted by Eric Baker

What's it doing when it won't start? Does it crank but not catch? Does it not crank but everything in the car is on? Could have a faulty battery or alternator. Anything done to the car electrically, like stereo or lighting?

It won't even crank. Just a tick and quietness. No electronic update so far.

I took the car in and the shop couldn't find anything wrong so they're holding the car for a few days to test drive the car and to reproduce the problem. Battery and starter both tested out fine. They're thinking of reflashing the computer ecm.

montreal2010yellow · 02-14-2011, 11:30 AM

Had just about the same situation last year....it was just a loose battrery cable/clip on the post.

Goliath · 02-14-2011, 11:49 AM

Quote:

Originally Posted by montreal2010yellow

Had just about the same situation last year....it was just a loose battrery cable/clip on the post.

I triple checked and nothing was loose. Even the starter wire clip and harness are all tighted.

Car is #2094 bought used last year. Not sure the previous owner tuned the car or not (crossed-fingers).

02-13-2011, 01:00 PM	#1
Goliath Drives: 2010 Camaro 1SS L99 A6 Join Date: Nov 2010 Location: Texas Posts: 216	Battery Voltage fluctuate - Normal? It is normal to have battery voltage fluctuation from 12.0 - 14.5 volt while driving ? Thanks. __________________ The Most Interesting Man in the World - On Muscle Cars "I don't always drive muscle car, but when I do, I prefer the Camaro. " Last edited by Goliath; 02-13-2011 at 06:06 PM.

02-13-2011, 01:20 PM	#3
Goliath Drives: 2010 Camaro 1SS L99 A6 Join Date: Nov 2010 Location: Texas Posts: 216	Thanks. While driving and idle, I see my battery voltage was at 12.0v for a while and didn't go up above 13.0v while driving at 30mph. After parked and turned off the engine, I couldn't restart the car. This intermit "can't start engine" is pissing me off. Left the car for 15 minutes and it start right back like nothing has happened. Any idea? __________________ The Most Interesting Man in the World - On Muscle Cars "I don't always drive muscle car, but when I do, I prefer the Camaro. "

02-13-2011, 09:01 PM	#6
fielderLS3 Drives: 2016 Mazda6, 2011 Mustang 5.0 Join Date: Mar 2010 Location: Portage, Wisconsin Posts: 4,049	Battery voltage can fluctuate on newer cars depending on how much power the car is using, how charged up the battery is, and even depending on when the computer thinks it is more or less energy efficient to charge or not to charge depending on driving conditions. __________________ 2022 1SS 1LE (Arrived 4/29/22) "The car is the closest thing we will ever create to something that is alive." . 2022 1SS 1LE (Coming Soon)

02-14-2011, 11:30 AM	#8
montreal2010yellow Drives: 2 LT/RS YELLOW, AUTO., VIN NO. 602 Join Date: May 2010 Location: LAVAL (10 min. north of Montreal), CANADA Posts: 3,526 View My Garage	Had just about the same situation last year....it was just a loose battrery cable/clip on the post. __________________ T2 Facia, ACS TL1 Hood, ACS Winglets. G5CR CAI. Hotchsic Strut Brace and more...

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02-13-2011, 01:09 PM	#2
Eric Baker Drives: Black/Black 2SS/RS 6M Join Date: Mar 2010 Location: Boston MA Posts: 987 View My Garage	It's normal for it to fluctuate a little, but it should always be above 13.5v.

02-13-2011, 08:20 PM	#4
Eric Baker Drives: Black/Black 2SS/RS 6M Join Date: Mar 2010 Location: Boston MA Posts: 987 View My Garage	What's it doing when it won't start? Does it crank but not catch? Does it not crank but everything in the car is on? Could have a faulty battery or alternator. Anything done to the car electrically, like stereo or lighting?

02-13-2011, 08:56 PM	#5
turboguy327 Banned Drives: 2011 Chevy Camaro Join Date: Sep 2010 Location: USA Posts: 704	The BCM controls the alternators output through PWM. So the voltage will vary as the BCM sees fit for the given current draw. If your not using a lot of power the BCM will cut the alternator back. Supposedly it lasts longer that way. All the newer cars are like this.