Question: what is the function of the alternator in a car
[{'answer': 'charge the battery', 'provenance': [{'wikipedia_id': '40400151', 'title': 'Alternator (automotive)', 'start_paragraph_id': 1, 'start_character': 46, 'end_paragraph_id': 1, 'end_character': 64, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'power the electrical system when its engine is running'}, {'provenance': [{'wikipedia_id': '40400151', 'title': 'Alternator (automotive)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 126, 'bleu_score': 0.9067110266941041, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6231991075657931474}, 'section': 'Section::::Abstract.'}]}]