I found this in the manual. "NOTICE : The hybrid system contains many electronic components. High voltage components, such as cables and other parts, may emit electromagnetic waves. Even when the electromagnetic cover blocks electromagnetic emissions, electromagnetic waves may have an effect on electronic devices. When your vehicle is not used for a long period of time, the hybrid system will discharge. You need to drive the vehicle several times a month. We recommend driving at least for 1 hour or 10 miles. When the hybrid battery is discharged, or when it is impossible to jump start the vehicle, we recommend that you contact your authorized HYUNDAI dealer ". It also says this about the 12 volt system - "Battery : The vehicle is composed of a high voltage battery that drives the motor and air conditioner, and an integrated 12V lead battery with the HEV battery that drives the lamps, wipers, and audio system. • The integrated 12V battery is automatically charged when the vehicle is in the "ready" mode." If this is accurate, the 12 volt battery is only maintained when the car is powered on, so my suggestion about charging up the traction battery may not be helpful.