Voltage Question
Thread Starter
Drifting
Joined: Jul 2011
Posts: 1,599
Likes: 398
From: Boise, ID
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
C5 of Year Finalist (appearance mods) 2019
Voltage Question
I had an issue today where I went to start my car in a parking lot after driving and I had to crank the car twice to get it to start. I have a new starter that I torqued down the cables to it and also have checked torque on alternator and battery terminals. When driving I am seeing 13.6 other 13.7v with no accessories on and 13.3v with headlights on. Seems to be a tad low, thoughts?
My battery is an optima red top and is several years old, alternator is original. I tested voltage while car was running at the battery I was seeing 13.95v and 14.3v at alternator using my multimeter but am seeing lower voltage on DIC what are potential culprits for the diecrepancies? Thanks.
My battery is an optima red top and is several years old, alternator is original. I tested voltage while car was running at the battery I was seeing 13.95v and 14.3v at alternator using my multimeter but am seeing lower voltage on DIC what are potential culprits for the diecrepancies? Thanks.
Last edited by tommypenguin; Feb 12, 2016 at 12:08 AM.
Melting Slicks
Joined: Jul 2004
Posts: 3,290
Likes: 477
From: Brea CA
Check the voltage at the alternator and battery. they should be within tenths of a volt. The volt meter on the dash will read less than this.
The voltage at the alternator you state is good, just need to know what it is across the battery.
The volt meter on the dash provides the voltage after a whole bunch of electronics and switches. One area the can be an issue is the ignition switch. The contacts there tend to get carbon buildup from arcing. All C5's will have this issue. The bad contacts will manifest all kinds of issues from lost communication between modules, possible active handling errors and other controls not working consistently.
There is a sticky at the top of this section called Important Electrical Information. This is the bible on electrical issues.
So after all that, for your issue is the battery voltage and alternator voltage the same with the car running. If so you probably do not have an issue at this time.
Gary
The voltage at the alternator you state is good, just need to know what it is across the battery.
The volt meter on the dash provides the voltage after a whole bunch of electronics and switches. One area the can be an issue is the ignition switch. The contacts there tend to get carbon buildup from arcing. All C5's will have this issue. The bad contacts will manifest all kinds of issues from lost communication between modules, possible active handling errors and other controls not working consistently.
There is a sticky at the top of this section called Important Electrical Information. This is the bible on electrical issues.
So after all that, for your issue is the battery voltage and alternator voltage the same with the car running. If so you probably do not have an issue at this time.
Gary
Acct Suspended APR 2026 by request
Joined: Dec 2010
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2020 Corvette of the Year Finalist (performance mods)
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do you think maybe the starting issue was fuel related and had nothing to do with the battery?
Melting Slicks
Joined: Jan 2009
Posts: 3,275
Likes: 739
From: Miami FL
OP, did you clean all contacts at alternator, starter and battery before connecting and torquing (especially at starter, since you just replaced it)?
In general terms your readings seem normal and the difference between DIC and multimeter is due to what's already been explained above.
Last edited by GCG; Feb 16, 2016 at 12:52 AM.
Thread Starter
Drifting
Joined: Jul 2011
Posts: 1,599
Likes: 398
From: Boise, ID
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
C5 of Year Finalist (appearance mods) 2019
Melting Slicks
Joined: Sep 2007
Posts: 2,133
Likes: 139
From: Port St Lucie Florida
Just for the record, I took a volt meter and measured the battery and alternator and could not believe the voltage coming from it. Car was started for about 10 min and the alt measured like 14.8 volts and battery was 14.5 volts, while DIC reads 13.6, I heard the DIC is actually reading the ignition switch and not the battery. To get a true battery reading, measure the batt terminals while motor is running. That's what I did.
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Drifting
Joined: Oct 2011
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From: Olmsted Falls Ohio
St. Jude Donor '12 thru '24
Just an off the wall consideration. A couple times over the years, I've started the C5 and after turning the key to the 'start' position, I let go of the key entirely as it 'snaps' or returns back toward the 'run' position. Depending on how much grip I have on the key, it will sometimes snap past the run position back towards off. This causes the engine to quickly stop. First time it happened, I'm thinking 'What's going on here?' Put my fingers back on the key and realize it is not quite in the run position. Keeping my fingers lightly on the key while starting keeps this from happening. Ignition switch contacts are in good shape.