You do not need to disconnect the battery cables to charge it while it is in the vehicle. Remember, certain vehicle settings may be lost if the battery is disconnected without another power source going to the vehicle. We advise using a smart multi-stage charger which can vary the charge rate as needed by the battery.
Make sure the charger is turned off and the vehicle ignition is off. Then connect the charger’s positive cable to the battery’s positive terminal and do the same with the negative cable and terminal. When complete, turn off the charger and disconnect the negative charger cable and then the positive one.
Always read the manual for both your vehicle and the charger for specific safety information.