a volt- or multi- meter would be handy here, although not necessary. you should be showing +12V with the car not running and +13-14V with the alternator spinning.
most auto parts stores will test your battery and / or alternator and starter for you if necessary.
and, as Bob says, cleaning contacts can't hurt.
The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
Government schooling is about "the perfect organization of the hive."
H.H. Goddard, Human Efficiency (1920)