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]

Something is very wrong. A fully charged battery will give 12.8 volts across the posts. Your alternator is not charging the battery properly. You will have to use a voltmeter to find the various voltages around the system. Even check such things as the voltage difference between the negative post and the alternator housing ( the alternator is grounded through its case to the engine case, to the tranny, the tranny ground strap, the car body and the ground lead between the body and the battery post. A quick check may be to ground the battery post directly to the fan shroud to see if that makes any difference. You need to get close to 14 volts at the battery posts to have proper charging. The heat of the engine can cause resistance to increase along the current path. You will have to find out where. What state is the battery in? Does it have water?