(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 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 is now
fixed up; he will be all
right for something, or what he has had will now be over.
—SHSBC Binder 20 Approved Glossary