Charging via petrol

[ehsbcn]

Straight forward question:

Is it worth it to charge the electric battery while driving in a highway on petrol?

Further questions:
Should I deplete the battery and then switch to petrol on long distances?

Is there a maintenance reason to have always some battery left?

 

[Jto]

1 cost a lot to charge the battery from the engine so not recommended
2 on doing a long distance leave the car on auto so it decides which to us