Electrical problem
1994 Ford F150 6 cyl Two Wheel Drive Automatic

I hope someone can help me here. As the description says I have a old 1994 Ford F150, in great condition expect for big electrical problem, the battery will not hold a charge. I have replaced the Alternator, Alternator wiring harness, Volt Regulator, and the battery but the problem still remains. I have to charge the battery every night just to drive for the day! I have gotten ideas from a bad grounding to a draw on the battery.

Also a mechanic friend looked at for me and found that the battery had more power when the truck is off then on. Now I'm just looking for more information on what the problem can be or a solution to this problem. I really need some help! Either more ideas or a cheap and easy way to fix it. Please!