I agree: probably something is wrong with the kindle if it drains a battery so quickly. HOWEVER, just to be sure -- did you put lots of books on it all at once? In that case perhaps it is indexing? That does drain the battery more quickly, although maybe not quite so fast. My k1 still charges easily in 2 hours with a year-old battery (wall charger, not usb to computer) and takes several days to start showing a discharge. Remember too that the battery charge image is not linear.
Also, it is true that the K1 was never meant to charge via usb.