Voltage indication question
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Race Director
Joined: Jul 2000
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
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Voltage indication question
I've noticed my gauge reads low when I first start up and slowly moves to the correct reading. Is my problem the gauge, battery, or alternator? The battery is a two year old Optima red top. The alternator is original (1998).
The car starts fine even after sitting for a week.
The car starts fine even after sitting for a week.
Burning Brakes
Joined: Jan 2005
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From: Frankfort Illinois
My 99' with a new battery will read high 12's or around 12.8 volts while car is off. When cranking it will drop to high 10's or say about 10.75 & then build immediately up to 14.1 - 14.3 hope that helps
Thread Starter
Race Director
Joined: Jul 2000
Posts: 16,487
Likes: 2,376
From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
2020 C6 of the Year Finalist - Modified
Originally Posted by JEEP/C5
What is your gage reading when your first start it and after it runs. If you start it and run it for 30 min then restart what is it at?
Instructor
Joined: Nov 2001
Posts: 107
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From: Hockessin DE
The reading before you start is the battery reading, after start up you are reading the charging voltage from the alternator. The gage does have a lag, but if you shut it off and turn back on to start position so that the gages react but DON'T start the engine, you're reading battery volts only. Make sure most things are off like radio, HVAC fan, etc. Should read 12V. Since there are 6 cells in a 12V battery, if one is dead you get 10V.
