the alternator/generator has nothing to do with a car starting its there for the sole purpose of recharging the battery.
if you r voltage on your battery is dropping after recharging it then your alternator is definately at fault here. its not working .
first see if any of the power wires from the alternator are loose or corroded. my buddy replaced 4 alternators on his se-r everytime i told him to see if his wires where good then finally the 5th time he told me he tugged on the wire and it just came off.
so check the easy stuff first <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt='
'> main problem is near your alternator