Detroit has just 36 wins after 138 games this season and need to win seven of their last 24 to avoid the dubious worst-ever record held by the 1962 New York Mets, who finished with 120 losses.
The Tigers have played much better of late, splitting their last 10 games after Halter's heroics. He won the game with his ninth homer, driving a 1-0 pitch from Santiago (1-2) off the outer edge of the left field pole.
Jamie Walker (4-3) recorded the victory after getting the final two outs in the 11th. Detroit was one out away from winning in the ninth before Fernando Rodney gave up a game-tying single to Ben Broussard.