anyone else have this problem?? mine has just started doing this..with all accesories on such as radio with amp .. lights .. neons. blower motor etc it reads about ten volts at idle.. which is not the case .. i used a test meter at the battery and it is about 13.8 at idle.. the battery itself is at 12.45 without the engine running.. i am assuming the gauge is just old and worn out and wonder if a new one will fix the prob.. where do they ground to if anyone knows. thanks.. Dave..