Voltage discrepancy, WTF? |
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Voltage discrepancy, WTF? |
saigon71 |
Dec 11 2018, 06:17 PM
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#1
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Senior Member Group: Members Posts: 1,999 Joined: 1-June 09 From: Dillsburg, PA Member No.: 10,428 Region Association: MidAtlantic Region |
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? |
adolimpio |
Dec 11 2018, 07:09 PM
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#2
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Art Group: Members Posts: 181 Joined: 10-March 10 From: Greenwood SC Member No.: 11,449 Region Association: South East States |
Ohm's law. Voltage drops as current passes through a conductor, increasing with resistance of conductor. Measuring at the battery, very little resistance between source and measuring point, so no voltage drop.
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