Synonyms for Batty (same or very similar meaning)
WordNet sense 1 (informal or slang terms for mentally irregular):
balmy, bonkers, buggy, cracked, crackers, daft, dotty, fruity, haywire, kooky, loco, loony, loopy, nuts, nutty, wacky, barmy, kookie, whacky, around the bend, bats, round the bend
WordNet sense 2 (afflicted with or characteristic of mental derangement):
insane
From the ODE community, based on WordNet
add/edit