 Voltage discrepancy, WTF? |
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| saigon71 |
 Dec 11 2018, 06:17 PM
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#1
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Senior Member  Group: Members Posts: 1,998 Joined: 1-June 09 From: Dillsburg, PA Member No.: 10,428 Region Association: MidAtlantic Region 
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As long as I can remember, when driving at night in the 914, my center console voltmeter hovers right around 12V when cruising with the lights on. When I hit the brakes, it drops well below 12V...anything else drops it even lower.
I'm running an Optima Red Top near the end of it's service life and want to make sure my charging system is healthy before popping on a new AGM battery. I had been considering switching to LED headlights and brake lights to lower the current draw. I hooked up the VOM at the battery and did a load test with the car running, adding an accessory at a time. With headlights, brake lights and aux fan on the voltmeter in the center console read just over as 10 volts, while the VOM hooked to the battery showed 12.58V. Is this discrepancy normal?   |
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| toolguy |
Dec 11 2018, 06:23 PM
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#2
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Senior Member Group: Members Posts: 1,267 Joined: 2-April 11 From: San Diego / El Cajon Member No.: 12,889 Region Association: Southern California
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perfectly normal and as expected. . old wire with poor connections, as well as bad grounding lugs are the most probable cause. . each connection sucks out a few 1/10 of a volt till they add up. . .
Check the main battery ground and positive leads 1st, then work your way vack thru the wiring. . don't forget the trans ground strap |
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Posts in this topic
saigon71 Voltage discrepancy Dec 11 2018, 06:17 PM
TheCabinetmaker Nothing to do with old wires! They worked like... Dec 11 2018, 06:56 PM adolimpio Ohm's law. Voltage drops as current passes thr... Dec 11 2018, 07:09 PM North Coast Jim You also could have lost the ground connection wit... Dec 11 2018, 07:21 PM
dr914@autoatlanta.com
You also could have lost the ground connection wi... Dec 12 2018, 09:09 AM PanelBilly I added a new ground wire to mine and that fixed i... Dec 11 2018, 08:08 PM GregAmy Is this discrepancy normal?
Yes. This is why I de... Dec 11 2018, 08:21 PM campbellcj I'm fighting the same issue now too, and it wa... Dec 12 2018, 08:56 AM ClayPerrine The volt meter in the center console is nowhere ne... Dec 12 2018, 09:00 AM Spoke
With headlights, brake lights and aux fan on the ... Dec 12 2018, 08:49 PM Dave_Darling I like to say that the voltmeter is there "fo... Dec 12 2018, 10:48 PM |
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