Sitting at red light, ac off, blower on 2, rear defog turned on. Both wipers on, head lights and fog lights turned on. Battery light came on. Turned off defog switch and withen a couple seconds battery light went off. Battery is 6 months old. Is this light triggered be a low voltage event? (like load was more than alt put out at idle and voltage dropped Is this an indicator my altinator is going bad?