The battery does not pull amps from the turbine.
The turbine forces amps into the battery.
Depends on the wind turbines open voltage at the time. The turbine's open voltage has to be higher than the battery voltage for amps to flow into the battery.
Sounds like the turbine has the battery mostly full charged, but has not done any charging in the last day or 2. The battery has gone down to standing voltage, which is about 12.65V when 'full'.
G-