Rover Controller Status Modes

During 'MPPT', the battery is charging from some starting pt until the battery gets to Boost voltage.
Max power point of the panels is transformed to battery voltage, the battery accepts all the power and its voltage rises.
This continues until the battery has risen to boost voltage. There is no set voltage for this mode.

During Boost and Float the controller is maintaining a constant battery voltage.
Battery acceptance determines how much the controller limits power to the battery to maintain its voltage constant.
During Boost, less and less power is needed to maintain voltage as the battery approaches full.
Little power is needed to maintain Float voltage.

During Boost and Float there should be excess power available for other use (other than charging).

Baby its cold outside! the cold jacks up the voltage due to temp correction! Chemical reactions slow in the cold so it takes more voltage to get the juices flowing. in short boost voltage is the controlling voltage for charging.