(slang) an artillery
term. A
gun, after it fires, is said to go out of
battery, which is to say, it recoils. Then after it is
fired it is supposed to revert to (go back to)
battery, which is sitting the way you see them in photographs. It is used as a
slang term to indicate somebody who will be
fixed up; he will be all
right for something, or what he has had will be over.
—Academy Level IV Glossary