Maybe I'm blind but the Energy Cubes and the Induction Matrix only show how much energy they are currently Storing and not how much they can store.

Not blind, I was just looking at my induction matrix thinking the same thing. Would be a nice bit to add both on the power tab [bottom left] and also on the statistics screen in the case of the matrix.

I agree, it can be even shown as
%stored%/%total capacity%

Reopened as I've only done energy, not the fluids.

This request has been added to the master list at #5322

In order to keep issue numbers under control this issue will be closed and used as future reference.