C battery vs electric battery

C battery and electric battery both are nouns.

Word	Noun	Adjective	Verb	Adverb
C battery	Yes	No	No	No
electric battery	Yes	No	No	No

As nouns, electric battery is a hypernym of C battery; that is, electric battery is a word with a broader meaning than C battery:

C battery: battery used to maintain the grid potential in a vacuum tube
electric battery: a device that produces electricity; may have several primary or secondary cells arranged in parallel or series

Other hypernyms of C battery include battery.

C battery (noun)	electric battery (noun)
battery used to maintain the grid potential in a vacuum tube	a device that produces electricity; may have several primary or secondary cells arranged in parallel or series