define a array of image id like this
int[] p = {R.drawable.image1, R.drawable.image2....}
now for different condition use member of this array like
Battery.setBackgroundResource(p[0]) // or p[1]
or you can use ENUM to make it more readable..
But.. I think you should think in another way. instead of using 100 different image create a custom progressbar to show different state of your battery.
To know the basics of Progress bar see doc here and to create custom progressbar you can check this so question