Recharging 12V battery

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.

When electromotive force α (unit: V) of the solar cell module exceeds 12V battery voltage in the sun, the 12V battery is recharged at a current responsive to α.
The 12V battery is not recharged when electromotive force α falls below battery voltage.