ok i was testing my alternator and when im run my car with 65watt bulbs my volts drop from 14.3 to 13.6 and varies up and down when i turn the heater on it goes to 12.10 anyone know if this means my alternator is going bad or something else my alternator powers at 14v on idle but doesnt seem to charge fast someone said i may need a rebuld anyone else have some appinions