Q: Battery light on when you turn on car

Hi There, Cold weather can be especially harsh on batteries as you may know. The battery light will usually come on for a few seconds upon start up as it does a system check, however it should turn off after about 5 seconds or so. If it stays on longer than this, it may indicate you have a failing or weak battery or something else wrong within your charging system such as a faulty alternator or voltage regulator. The voltage regulator is a unit that regulates the charging of the battery by the alternator and maintaining a certain amperage while the engine runs. When the alternator is not working properly, this may result in the battery quickly losing charge and the car losing all power as you have described. You may also notice a whining sound as a result of the bearings inside the alternator begin to fail. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your charging system.