I've got a problems with my alternator charging my battery. When I crank it up, it's almost half on the gauge. Then I drive around for a minute and it starts to drop. It's keeping a charge, it's just like it's having a problem. The alternator is not even a year old and the battery was replaced not too long ago. On the interstate, it flucuates a lot and it seems like it would keep a steady charge since the rpms are steady. Anyone else have a problem like this?