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Technical => Electrical and Ignition Systems => Topic started by: RICH MUISE on 2025-09-28 21:32

Title: voltmeter reading 12 volts
Post by: RICH MUISE on 2025-09-28 21:32
As above, my voltmeter is showing around 12.2-ish with the engine running and nothing on. If I turn on headlights or A/C, it drops below 12. I had the charging system checked, and he checked out the system at 14.2 volts. Haven't found any obvious issues yet, but a friend suggested it could be a bad cell in the battery............system putting in 14+ volts, but the battery only able to put out 12. I guess what my voltmeter is showing would depend on where the wiring for it goes to.? Does the battery issue my friend suggested sound feasible to you guys?
Title: Re: voltmeter reading 12 volts
Post by: Ford Blue blood on 2025-09-29 08:02
What voltage does the battery show with one of the leads removed engine off?  Also, with the battery connected put the meter on the battery terminals, note the voltage (should be in the 12.6 - 12.9 range), then with the meter still connected turn on the head lights and step on the brake pedal.  Voltage should only drop a few tenths if the battery is good.  If it drops into the 10 - 8V range bad battery.
Title: Re: voltmeter reading 12 volts
Post by: RICH MUISE on 2025-09-29 12:00
I had the battery checked.......it had a bad cell. It was 5 years old. I was sure that was the problem, but no. I bought a new Optima, same as the old one (306.), but my voltmeter is still reading a bit over 12 with the engine running, nothing on.
I wish my brain worked like it used to. I forgot to mention, until recently, the voltmeter was always above 13, would drop a little with A/C and headlights on
Title: Re: voltmeter reading 12 volts
Post by: RICH MUISE on 2025-09-29 16:59
Ok.issue found. It is in fact my voltmeter reading low. A meter reading at the input @ back of the gauge shows 14.1. Wires appeared to be tight, my mechanic told me, but whatever he did back there got the meter to read 13+, so, good for now. Replacing that gauge means replacing 4, so not in the near future.
Title: Re: voltmeter reading 12 volts
Post by: Ford Blue blood on 2025-09-30 07:37
 :003:
Title: Re: voltmeter reading 12 volts
Post by: cokefirst on 2025-09-30 09:50
At one time, dash gauges were called "indicators" since their accuracy was not consistent.