Battery can be a misdemeanor or felony depending on what type of injuries were sustained. If they live together (or used to), are married (or used to be to each other), or have a child together and the defendant caused a visible or "traumatic" injury, then it is likely a felony. If they are not living together and/or married and the Defendant caused no significant injury, then it's a misdemeanor.
CA Penal Code 243(e)(1) States:
"When a battery is committed against a spouse, a person with whom the defendant is cohabiting, a person who is the parent of the defendant's child, former spouse, fiance, or fiance, or a person with whom the defendant currently has, or has previously had, a dating or engagement relationship, the battery is punishable by a fine not exceeding two thousand dollars ($2,000), or by imprisonment in a county jail for a period of not more than one year; or by both that fine and imprisonment."
CA Penal Code 273.5:
"(a) Any person who willfully inflict's upon a person who is his or her spouse, former spouse, cohabitant, former cohabitant, or the mother or father of his or her child, corporal injury resulting in a traumatic condition, is guilty of a felony, and upon conviction thereof shall be punished by imprisonment in the state prison for two, three, or four years, or in a county jail for not more than one year or by a fine of up to six thousand dollars ($6,000) or by both that fine and imprisonment. (b) Holding oneself out to be the husband or wife of the person with whom one is cohabiting is not necessary to constitute cohabitation as the term is used in this section. (c) As used in this section, "traumatic condition" means a condition of the body, such as a wound or external or internal injury, whether of a minor or serious nature, caused by a physical force."
Many times we can get these cases dropped, without court