Battery light is ON only on first start
 

Hello,

My car is being weird recently.
When I start it, the first time, the battery light is ON. (cold mornings)

I turn it off, then I restart it. the battery light is gone :eek:

What would make the light of the battery turn on only in cold mornings and at the car's first start on the day. :confused:

Maybe the voltage regulator in the alternator going screwy?

My old Cavalier had a similar problem. Sometimes when starting the volts light would be on and it wouldn't charge. The mechanic showed me how to jump 2 wires at the alternator to give it a kick in the pants and get it to charge. It became so common that I wired a switch up to the dash so I didn't have to pop the hood every morning.

Might be a bad relay.

It is the alternator. When the battery light is on, it charges 11.3v and then when we restart again, it is 14v.

Looks like an intermittent fault in the voltage regulator circuit. Pull the board and post a picture of both sides for more troubleshooting.

I didn't mention, but I've replaced the alternator on July 2009, and it is on warranty. (except labor XD)
They will replace it next Friday (13 october)

In many power supply circuits, a common cause of intermittent failure to start up is a bad controller Vcc supply capacitor or resistor. If the resistor increases in value or the capacitor becomes leaky, the Vcc never gets high enough for the controller to start.