 Different voltmeter readings? |
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| SKL1 |
 Jul 14 2025, 08:44 PM
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#1
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Senior Member  Group: Members Posts: 1,713 Joined: 19-February 11 From: north Scottsdale Member No.: 12,732 Region Association: Upper MidWest 
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I've noticed with my '71, which has about 120K miles on it, the voltmeter is pretty much always reading around 11 V regardless of speed or revs.
In my '73, which has about 77K miles on it, it reads 11 or so at start up and for the first couple miles and then goes up to between 12 and 13. I swapped the voltage regulators for the heck of it and it didn't change anything. Is the older alternator from the '71 just worn out?? Not looking forward to changing it with the engine in the car!! |
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| Spoke |
Jul 14 2025, 10:46 PM
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Jerry Group: Members Posts: 7,193 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None
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The dash voltmeter on my '71 reads between 12-13.5V. The dash voltmeter is far away electrically from the battery to give accurate readings. You should check the battery voltage with a DMM.
Does the GEN light come on with key-on and go out when the engine is started? |
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| emerygt350 |
Jul 15 2025, 03:49 AM
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Advanced Member Group: Members Posts: 3,036 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
That dash volt meter is great for reminding you the blinker is on, and that's all. I put a relay in and wired mine direct to the battery. Now it is useful. The original wiring to the meter now turns on the relay which brings fused 12v direct (more like 13.7 when the car is running) to gauge. No damage to the original wiring and works great.
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| porschetub |
Jul 15 2025, 05:18 PM
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Advanced Member Group: Members Posts: 4,886 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
QUOTE(emerygt350 @ Jul 15 2025, 09:49 PM)  That dash volt meter is great for reminding you the blinker is on, and that's all. I put a relay in and wired mine direct to the battery. Now it is useful. The original wiring to the meter now turns on the relay which brings fused 12v direct (more like 13.7 when the car is running) to gauge. No damage to the original wiring and works great. I found too much signal loss and my voltmeter wouldn't read any more than 12v powered off old centre console wiring,changed the supply to my Hella aux fuse board with direct feed to battery and achieved the correct reading as per battery . Cheers. |
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| SKL1 |
Jul 15 2025, 07:25 PM
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#5
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Senior Member Group: Members Posts: 1,713 Joined: 19-February 11 From: north Scottsdale Member No.: 12,732 Region Association: Upper MidWest
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Good to know. Thx guys.
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