(slang) an artillery
term. A
gun, after it fires, is said to go out of
battery, which is to say, it recoils. Then it is supposed to go back to
battery, which is sitting the way you see a
gun 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 33 Approved Glossary