We are probably over-analyzing this, but in your original, you said "the batteries."
My assumption, if I read it without any context, would be that whatever you're running COULD use batteries or could use something else (like a power cord). I come in and find my husband using my laptop and it's not plugged in. I know the battery doesn't last that long: "You're running that thing off th
Diddy, it would help-it always does-if you would frame your question about the phrase by first using the phrase in a complete sentence. Otherwise, it's too confusing to know what you are really asking.