I have two new batteries, replaced alternator, replaced ground wire from alternator to block, replaced ground wire from battery to block, all of the lights light up on dash when I turn key on to position 2. The alternator does charge the battery some because I can see the voltage rising at the battery with my multimeter while idling. However, something is severely draining the battery when I am driving down the road. Usually by the time I drive to school 25 miles away and back, when I pull into the driveway in the afternoon the battery is completely unable to start the car. I have to carry an extra battery in the trunk because I have been stranded too many times.

Any ideas what the problem is here?