I had a similar problem with my 1G. It turned out to be the Alternator fuse in the engine bay by the battery. My battery kept dying even after installing a new alternator. Anyway, from the top view the fuse looked fine, but once removed you could tell it was fried from the side - only way you can see it is by removing it. Hope this helps.Well I think I have an idea. One day I thought I’ve connected everything to the battery but forgot to connect the alternator wire. The car idles until I lost all voltage needed to run (battery died). Then I took off my alternator thinking that it was bad and had it checked (like 5 times). It passed all 5 times. So when I decided to put everything back together I realized that the alternator cable wasn't connected to the battery. I connected ALL the wires and the car charged (14v at idle and 12v when off). 2 days later, after thinking that I’ve fixed it, I tried to turn the car on and the battery is dead. Before I connected everything the battery could stay in the car for a couple of days without dying (alternator wire not connected).
I saw my alternator and compared to other DSM and some cars has their alternator grounded. My alternator is not grounded; can it cause the battery to die?