Defective alternator or internal voltage regulator is bad.
how to reset the batterie light
A bad belt, a bad regulator in the alternator or bad brushes in the alternator.
Defective alternator or internal voltage regulator is bad.
Check volatages everywhere, there could be a short somewhere. Also, check the tension on the belt that drives your alternator. That belt might be slipping due to a faulty tensioner and not spinning the alternator fast enough.
Bad voltage regulator
The positive cable between the alternator and the battery has an open circuit or break. There also is a set of wires that plug into the alternator that turns it on when the car is running. Wiring problems here can cause a alternator not to charge on the vehicle but works fine on a test stand. Some cars the alternator light in the dash causes the alternator to kick in when the engine is started. A burned out light in the dash causes the alternator not to charge.
same problem what the answer
could be a bad battery
Charge it, replace it,test the alternator,Charge it, replace it,test the alternator,
Any alternator will charge at idle.
Worn brushes, bad Regulator, or Likely a bad connection or wiring.
alternator is bad