Plurals amplified
Incorrect: battery's charged (from a sign, of course, meaning more than one battery)
Correct: batteries charged
Note the spelling at the end of the word changed, too. HOWEVER, just when I think I have an all-inclusive rule, I remember (or my wife reminds me) "Yes, dear. The battery's charged." The contraction apostrophe strikes again. You probably won't have a contraction in a well-written resume, though.
I agree; there are too many inconsistent rules. Asking people to use a paper dictionary may be too much, but typing the word into Google will do the job a good bit of the time. Asking a friend whose grammar you trust to proofread your documents will help even more, particularly if that friend is good at looking up stuff she/he doesn't know.
