Volt Reading
Thread Starter
Race Director
Joined: Nov 2002
Posts: 19,149
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From: First to Sign Grumpy's Hat Only 53 miles from Hell
St. Jude Donor '06-'09-'10-'11
Volt Reading
Can anyone tell me what should be the volt reading from the alternator on a fully charged battery on a 93?
After an hour of driving around the digital volt reading shows anywhere around 13.8 to 14.1v. I thought it would drop down after starting to around 12v.
Thanks
After an hour of driving around the digital volt reading shows anywhere around 13.8 to 14.1v. I thought it would drop down after starting to around 12v.
Thanks
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Those reading are just fine and in the right range. Once the car is running, there are a lot of systems using electrical power and the alternator has to keep up with the load and keeping the battery charged.
With the engine and key off and using a voltmeter, you should see about 12.5v at the battery if it's fully charged.
With the engine and key off and using a voltmeter, you should see about 12.5v at the battery if it's fully charged.
Thread Starter
Race Director
Joined: Nov 2002
Posts: 19,149
Likes: 2
From: First to Sign Grumpy's Hat Only 53 miles from Hell
St. Jude Donor '06-'09-'10-'11
Wow, ok. Cool. Only reason I bring it up is because the Suburban I have now stays around 12v. It will go just over 14v after start up then slowly drops done.
Thanks guys.
Thanks guys.
Instructor
Joined: Sep 2003
Posts: 169
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From: Lewis Center OH
Don't mean to hijack your post, but when I run the AC it drops the volts down to about 12.1 to 12.2V. It puts a pretty good load on the system. The turn signals even slow down. The voltage picks back up when the compressor cycles off, but it just seems like it shouldn't effect the lights, signals etc. Any ideas?
Team Owner
Joined: Aug 2004
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From: Sussex,Wi
2023 Corvette of the Year Finalist - Unmodified
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Don't mean to hijack your post, but when I run the AC it drops the volts down to about 12.1 to 12.2V. It puts a pretty good load on the system. The turn signals even slow down. The voltage picks back up when the compressor cycles off, but it just seems like it shouldn't effect the lights, signals etc. Any ideas?
My Blazer runs a little over 13.5V with the A/C on at idle.
Running a cruise speed, it's up to 14V.
14.7 with A/C off.
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
At 12.1 volts, you are running on your battery! I would first measure the voltage across the battery terminals and compare it to the dash voltmeter. Unless you have too low idle rpm, your dash voltmeter should read around 14 volts alternator cold and around 13 volts alterator hot.
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Instructor
Joined: Sep 2003
Posts: 169
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From: Lewis Center OH
Do you have a high output alternator? I replecd mine with a stock unit from AC Delco about 2-years ago. It runs between 13 and 14 under normal load, but as soon as I start the A/C it drops it way down and the lights dim and the signals slow etc. I run a trickle charge when I'm not driving. I think the previous owner replaced the battery in 2001 or2002, not positive. Any ideas would be great. Thanks.
