[Plugin: WP-PostRatings] How to make it work with w3 total cache

I think you have to exclude the plugin’s java / ajax files from the minify feature. Or disable Minify entirely. (This is not a professional answer, its a suggestion only).

minify is disabled, but it doesn’t work

Did the WP Post Ratings author explain how the plugin should work with caching?

Nope.

Referring to the author’s website forum, there is information on how to make WP-PostRatings work with WP-SuperCache. This might be helpful.

https://forums.lesterchan.net/index.php?topic=4281.0

AJAX implementations are definitely the way to go when page caching is in place.