A second CDV battery charge within a year is a serious situation and the repeat nature of it is what changes the calculus most significantly.
Judges take a dim view of domestic violence repeat offenses, and a second charge within twelve months tells the court that the first charge produced no behavioral change. That pattern is exactly what drives harsher sentencing decisions. The leniency that sometimes exists for a first offense is largely gone by the time someone is standing before a judge on the same charge again.
The variables that determine the actual sentence are significant. The severity of the injury sustained by the victim, whether any weapons were involved, whether children were present during the incident, and what happened at sentencing on the first charge all factor into what the judge does this time. If the first charge resulted in a suspended sentence, probation, or a diversion program, the court is now in the position of deciding whether any non-incarceration option is still appropriate given the repeat conduct. In most cases the answer is no.
County jail time is a near certainty for a second offense of this nature. Whether it stops at county or escalates to state prison depends on how the charge is classified in the jurisdiction, what the first sentence looked like, and how aggressively the prosecution pursues it. Enhanced sentencing provisions for repeat domestic violence offenders exist in many states and can significantly increase the exposure beyond what the base charge carries.
He needs an experienced criminal defense attorney immediately. The prior charge, the timeline, and any victim injury documentation are all factors that require skilled legal navigation before this reaches a courtroom.