There is a light. The problem is if only 1 is charging, you'll still see the "charging" light while the other slowly loses battery.

I've dealt with this occasionally, from what I suspect is some buildup on the contacts due to sweat on my headphones from running. I find taking a cotton swap with alcohol to clean off the contacts every so often solves the problem.

The light only indicates the case is charging, you can take out both airpods (or have them not contacting properly) and the light will still come on.