Hyundai Repair: battery/altenator problems, realistic possibilities, fuse box

Question
I have a '99 Accent.  Went to start the car... nothing.  Got a boost and the car started up.  Unhooked the battery while car was running to check to see if it was the alternator... car ran fine.  Replaced with a new battery... worked like a charm.. at first.  Later that same day, went to start it up.... nothing.  Got a boost... started perfect.  Took the car for a long run to charge up the battery, went to start it again... nothing.  Also, may be related or not, but the wiring from the fan of the heater seems to be suspect.  I have the heater on full, then go over a bump, and the fan drops down a few notches.  Could wiring problems from the fan be affecting the wiring from the alternator to the battery?   Please Help.  

Answer
The blower motor should only be powered up when the ignition is on, so it's not likely this is the cause of your battery woes.  I think there are three realistic possibilities for the cause of your problem:

1.  The main 100A fuse in the underhood fuse box is blown.
2.  The alternator is working only intermittently.  This is often accompanied with an air bag warning lamp due to incorrect system voltage.
3.  There is a significant current draw on the battery while the vehicle is off.  Current draw when the vehicle is off should be less than 50mA.  More than 100mA often leads to issues with the battery running down.