OneCoolGT

I recently had Ford racing gauges installed to replace some carbon fiber autometers and noticed an issue with the volt gauge. When starting the car it'll read around 14 volts and around 13 when warm, on occasion it will drop to 12-12.5 if I'm sitting in traffic or if the fan or a/c is running. Had the charging system checked at the dealer and they said everything was fine, I'm thinking the gauge might be faulty or maybe my alternator (original) might be flaking out? The old volt gauge was always around 13 volts and never dropped.. is this normal? I attached a pic of the gauge while stopped, sorry it's sideways..couldn't figure out how to fix that.. any input would be appreciated. Thanks!

OneCoolGT

Anyone?? Is this a normal voltage with no accessories on.. lights, a/c and just fan running?

Red Gt

The car running with lights on and no ac it will read 13.45 volt.

RedGT

OneCoolGT

Thanks for the replies, when the lights are on with no a/c it will be around 12 with the fan running and 12.5-13 without.. I've never gotten a battery light or dimming of the lights, could the gauge be bad?

stupidgenius36

That sounds pretty normal for the most part. However, anything under 13V would have me questioning if the alternator was *starting* to give out. It may test ok now, but I'd keep an eye on it.

You won't get the battery light and "check charging system" warning in the cluster until you get under 11V.

The only precaution I can recommend would be to clean up and grease the battery terminals if there's any corrosion.

Cavero

The PCM will vary the amount of charging depending on under hood temperatures. Check out this thread ( start halfway down after I got a new battery)

https://themustangsource.com/forums/f637/p0622-code-charging-system-datalog-539499/

it would make sense your voltage would decrease sitting in traffic, the temperatures climb pretty quick under there when you're not moving

07 Boss

Put a meter to the battery and compare it to the gauge.

OneCoolGT

Thanks for the info! I notice it drops when the temp is hot out and been driving it for about a half hour or so, I'm gonna bring it in to a local shop and have them compare it to their readings. Think I might go with a 3-phase alternator when the original stocker calls it quits..

Cavero

You have a voltmeter? I'd check it yourself first like 07 Boss said, just as a sanity check to make sure the gauge doesn't have a bad ground or something either. If you have corrosion on the terminals, a higher temperature will increase its resistance and you'd get a lower reading. If you have an XCAL or OBD2 adapter you can read the voltage off the car's PCM too.