Is it normal for my volts 2 sit 3quarters way up gauge on batt meter on dash its highest wen i first strt the car but comes down 2 half way wen i put rear demister on, after about hlf an hour of driving it comes down an when idles drops below half way, could this b a knacked alternator thanx, amy x

 

sounds normal. When your car is first started say after it sits all night the RPMs are higher causing the alternator to turn faster producing more voltage. When the rear defroster is engaged it is using alot of amperage. After the engine warms up the idle slows down. Sounds like it operating correctly.

 

ive jus noticed ur message thanx for reply, silly me bought a new alternator ....and its the same but goin good haha