[mylesdw]

During normal driving it should be in the middle or very slightly to the positive side.

After starting the car, you should see a fairly large charge into the battery and then this will disappear within a few minutes.

When you switch on something like the fans which draw a bit of current, you should see the needle flick to the negative side and then recover immediatly (as long as the engine is running). It should never show a continual discharge.

It does sound like a problem with the charging system.