Just a thought, but I had problems viewing an icon I installed for my SMS. The problem was the Summerboard theme I was using. It had a lock on the icons. IF you're using Summerboard, try changing your theme to the default and see if it works then.
do u have an original png image in the folder. u should have a x.png, x-1.png,x-2.png, x-3.....and so on using x as just an example, so yurs might say batman.png or something but the name of the file is not important. the -1 parts of the file are all of the different stages of the battery up to 16 or 17, but u have to have a preview pic in the folder as well, so make sure u have a .png file for the battery because thats the image that will b used for the preview when u look under customize.
the battery isn't working because your files are not formatted for customize..
the format goes as follows..
if the battery name is "batman"
then you should have batman-1.png, batman-2.png...batman-16.png in increasing order of course..and the full battery image should be simply called "batman.png"
so in all u should have 17 images..the full battery image called "batman.png" and the rest in ascending order from batman-1.png to batman-16.png
really..thats very odd. r u not able to c the preview or is the battery itself not working? just a curious question though, does your battery files have a dash (-) or an underscore (_) after the batman part of the file? in customize, all the files must be a dash or it wont work. if yur trying to replace the main system battery not using customize, the file must be an underscore. thats the only other thing i can think of.