Car loses a volt as the engine warms up..., weird one Options

[anthony]

Ok, here's the situation. When I start the car cold I get 13.2 volts across the battery terminals. Perfect, right?

As the temperature gauge moves towards the middle of the gauge I slowly loose more voltage until I'm down to 12.2 volts.

Is this normal? I'm thinking that at full operating temperature with no accessores (lights, brake lights, etc) I should have full charging voltage. It seems that something is kicking in as the engine warms up and draws a full volt.

Are there any D-Jet components that would draw voltage as the car warms up.

The voltage drop is gradual. As the temperature gauge goes up the voltage gauge drops in sync. And this is not a faulty voltage gauge issue. I've verified this with a volt meter across the battery terminals.

[davep]

Engine not running, the battery should read 12.8 Volts. Running, about 13.8 volts.
It is a good sign that the idiot light appears to work normally.
Still, you will need to find out what the alternator output is at the alternator. You could have high voltage drops on both the positive and ground circuits between the alternator and the battery. I believe you can unplug the regulator from the board as well as the harness from the battery and just plug them together; in effect you bypass the relay board and that could be a soure of the problem. Try your spare VR as well. Essentially the car runs off of the alternator when the engine runs; the battery serves as a voltage reference and gets recharged while the engine runs.

I don't fool with my alternators. I get a local shop to rebuild them to 75 Amps output from the 50 amp original. That way it is rebuilt like new.