If your boyfriend was unarmed and assuming the battery was not on a pregnant person, an elderly person or public official such as law enforcement, Battery is a misdemeanor of the first degree carrying up to 1 year in jail. It can be charged as a third degree felony if your boyfriend has prior battery charges. Assault is a second degree misdemeanor carrying up to 60 days in jail. I suggest you consult with a local Criminal Defense attorney to discuss the facts in greater detail and learn your boyfriend's options. He may have some valid self defense claims. Good luck.
Is he still on probation? If so, there would be a new VOP.
If this is just a new charge, and these new charges are misdemeanors, he could face up to a year jail for the battery, and 60 days jail on the assault.
If he is charged with a misdemeanor battery than it is up to a year, if he has any prior batteries or is being charged with a felony battery than he can get between 5-15 depending on the charge. I would advise you to speak with an attorney asap to get more information.