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voltmeter question

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Aug 31, 2020, 8:31 PM

Post #1 of 3 (167 views)
voltmeter question Sign In

1932 Chevy streetrod. With engine running and electric fan running drawing 19 amps stewart warner in dash voltmeter is reading 12 volts. Testing 14 volts at battery that is located in trunk. 140 amp one wire gm alternator. If it is testing 14 volts at battery, why it it reading only 12 volts at gauge? When electric fan is shut off the voltmeter in dash jumps to 13.5 - 14 volts. Could this be a bad voltmeter gauge or something else? I took the car to a shop for a second opinion. They said Battery is good and alternator is charging fine. I just thought the in dash voltmeter should read the same as the battery. They said it could be the gauge.

Hammer Time
Ultimate Carjunky / Moderator
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Sep 1, 2020, 2:02 AM

Post #2 of 3 (163 views)
Re: voltmeter question Sign In

That depends on how the dash gauge is wired and where it is reading from. Yes, you would think they should match.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Sep 1, 2020, 3:09 AM

Post #3 of 3 (155 views)
Re: voltmeter question Sign In

? Whatever your creation it's a high draw fan - one wire alt (GM) is/seems right but is even a good SW gauge matching another for real voltage?
The draw may exceed what wire(s) can carry is still 12 where it's source is should be OK for the fan if same there but alternator should go hot on you and battery should be happy with this or it will be a problem later. If super low use "toy" thing/hobby all good fun may last for ages?
> Check that SW gauge once was the name to get IDK if adjustable or correct now been around forever - equipment of all sorts choose which types needed for your project as I recall,


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