I did ask this question a while back and the consensus was it doesn't put extra charge into the battery but rather by using the coasting of the car to drive the alternator which then puts power into the battery and not using fuel to drive the motor which drives the alternator.
In Green mode, pending on how cold the engine is, when you take your foot off the accelerator and 'coast' down a hill, you will either see a 'coasting' symbol on the screen or a 'battery' symbol.
The coasting symbol will show when the car reaches a certain operating temp. The car will disengage the drive (like being in Neutral) to minimize drag and you can basically maintain speed while going down a hill.
The battery symbol shows when the car is not up to temp, the car wont disengage the drive but as described above used the alternator to charge the battery with no engine input. The symbol also shows if your coasting and you touch the brakes or are under a certain speed, the gear will re-engage so no more coasting but the battery symbol will appear.
Hope that makes sense.
In Green mode, pending on how cold the engine is, when you take your foot off the accelerator and 'coast' down a hill, you will either see a 'coasting' symbol on the screen or a 'battery' symbol.
The coasting symbol will show when the car reaches a certain operating temp. The car will disengage the drive (like being in Neutral) to minimize drag and you can basically maintain speed while going down a hill.
The battery symbol shows when the car is not up to temp, the car wont disengage the drive but as described above used the alternator to charge the battery with no engine input. The symbol also shows if your coasting and you touch the brakes or are under a certain speed, the gear will re-engage so no more coasting but the battery symbol will appear.
Hope that makes sense.