AUTOMATIC 12V BATTERY CHARGE CONTROL: System Description: Description
WARNING: This page is about a different car, the 2011 Nissan Leaf. However, it is still accessible from the selected car via links, so may be relevant.
The automatic 12V battery charge control is a control to reduce the frequency of battery discharge by automatically charging the 12V battery in case the 12V battery voltage is low when the key switch is turned to ON or the vehicle has been left unattended for a long time.
When VCM recognizes a need of automatic charge, VCM controls the DC/DC converter and the system main relay and charges the 12V battery using the Li-ion battery power.
NOTE:
When setting the system to "READY" or starting Li-ion battery charge during automatic 12V battery charge, the automatic 12V battery charge is cancelled.