Volt meter issues, Solved |
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Volt meter issues, Solved |
PanelBilly |
Oct 15 2018, 09:38 AM
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#1
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914 Guru Group: Members Posts: 5,788 Joined: 23-July 06 From: Kent, Wa Member No.: 6,488 Region Association: Pacific Northwest |
My meter reads just under 12 volts when the engine is running. When I turn on any of the lights it pegs to the left. When I use a multimeter on the battery I get 13.67 volts at idle and just slightly under that when the lights go on.
Any ideas? |
dcheek |
Oct 15 2018, 09:52 AM
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#2
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Senior Member Group: Members Posts: 691 Joined: 30-May 06 From: Westfield, New Jersey Member No.: 6,103 |
My meter reads just under 12 volts when the engine is running. When I turn on any of the lights it pegs to the left. When I use a multimeter on the battery I get 13.67 volts at idle and just slightly under that when the lights go on. Any ideas? I had an erratic volt meter and it turn out to be the alternator. I first replaced the voltage regulator and cleaned the ground strap. When that didn't work I have the alternator rebuilt and its been fine ever since. Dave |
GregAmy |
Oct 15 2018, 09:54 AM
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#3
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Advanced Member Group: Members Posts: 2,262 Joined: 22-February 13 From: Middletown CT Member No.: 15,565 Region Association: North East States |
Remove it? Just kidding...
It's a showpiece item, not an accurate indicator of battery voltage. There's just too many (probably corroded) connections between it and the battery to be much use. Mine, for example, would fluctuate when I hit the brakes or used the turn signals; like you, it would show 12V when the battery was showing 13.5 at the terminals. Mine was showing much more accurately when I installed LED bulbs and replaced my panel with a JWest Engineering one. But I did both at the same time so I don't know which was effective. You could, I suppose, run a pair discrete wires directly to the battery, minimizing connections. That would be a very big step. In the end, I decided I didn't need a clock, didn't trust the voltmeter, and could be happy with the oil temp gauge in the fuel combo so I removed the center console, added the combo gauge, and gained some extra leg/calf room for my 6'1" frame. Quite happy with that decision. |
Dave_Darling |
Oct 15 2018, 10:51 AM
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#4
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914 Idiot Group: Members Posts: 14,974 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
Sounds like you have dirty connections somewhere in the circuit. The voltmeter typically reads over 12V when the engine is running, and drops down to maybe 10V with lots of lights and such on. (Note that the actual system voltage is closer to 14 when the engine is running and still generally over 12V with all the lights on!) There seems to be significant extra resistance in the circuit that's feeding your meter. Or in the ground for it.
--DD |
914Sixer |
Oct 15 2018, 04:42 PM
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#5
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914 Guru Group: Members Posts: 8,841 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region |
Pull the leads of the gauge and put a real volt/ohm meter and see what you get.
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Spoke |
Oct 16 2018, 03:56 AM
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#6
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Jerry Group: Members Posts: 6,964 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
My meter reads just under 12 volts when the engine is running. I checked the volt gauge in the center console in my 914 with a VOM and found the gauge to be less than 0.1V different than the VOM. As mentioned above, put your VOM on the back of the volt gauge and check the gauge's accuracy. The low reading shows how poorly the wiring/connections are performing in your 914. This could be wire resistance loss, ground and power connections. One way to check where losses are occurring is to measure different points along the electrical system by measuring dc voltages with respect to chassis ground. Put the negative probe of your VOM on a chassis bolt not used for electrical connections and measure voltage between: 1) The chassis and the negative connection on your volt gauge. Should be 0V 2) The chassis and the positive connection on your volt gauge. Should be 14V 3) The chassis and various fuses including the headlight fuses. Should be 14V 4) The chassis and the negative post of the battery. Not the clamp; the post. Should be 0V |
Valy |
Oct 17 2018, 10:24 AM
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#7
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Senior Member Group: Members Posts: 1,671 Joined: 6-April 10 From: Sunnyvale, CA Member No.: 11,573 Region Association: Northern California |
The gauge measures voltage where it is connected.
Don't look for the absolute value but do observe value at typical working conditions and make a mental note. When you see large drops in voltage it means the load on the circuit is higher. More than 3V constant drop should get your attention. |
PanelBilly |
Oct 19 2018, 02:39 PM
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#8
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914 Guru Group: Members Posts: 5,788 Joined: 23-July 06 From: Kent, Wa Member No.: 6,488 Region Association: Pacific Northwest |
It was the ground. I added another wire from the frame to the ground wire at the meter and all is good. Figured it wouldn’t hurt to add another ground to the network
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