This situation suggest one of two causes, although there could be other explanations.
You need to have a qualified automotive electrical Technician troubleshoot the entire wiring system of your vehicle, identify the defect, and properly repair it.
Have you checked the fuses?AnswerMay be a bad voltage regulator. alternator is no good without a voltage regulator. that's what "turns on" the alternator.
If the alternator is good then the battery is bad.
The battery may be defective and not able to take a charge.
put in new alternator but it will not charge battery. alternator was tested and found to be good. why wont it charge the battery?
If the alternator is good and the battery does not charge, then the battery may be bad. There could be problem with the electronics. You will need to take it to a place where they sell batteries. They have equipment to check out the battery and the wiring.
That is the purpose of an alternator. The keep the battery charged and to run all the electrics on the vehicle. However it is never a good idea to allow the alternator to charge a dead battery. This will put a strain on the alternator and may damage it.
It could be two things. As you know, the alternator charges the battery so it will not drain. If the alternator is not working properly to charge the battery, the battery will continuously drain. Have the alternator tested at your local Auto Parts store (NAPA or Advance Auto) If it is good, have the battery checked.
If you are 100% sure the battery and alternator are good and the battery is loosing it's charge then something is on pulling power from the battery. Can be any light or any relay on the vehicle.
The official charge of a battery is measured by the specific gravity of the electrolyte. For a good battery and alternator, full charge is noted when the alternator output current is just enough to carry the load, plus a bit to maintain the battery, and the battery voltage is normal.
The head lights, radio, and eveything else works, but the car will not start. I checked the starter and it was good. The battery is good, but whatever it is causes the battery to have a low charge. Could it be the alternator
is your battery Low or poor?? Charge your battery on slow charge for 8hrs to give it a good deep charge, Installing an alternator on a low or dead battery will ruin it and also not charge your battery properly.. An alternator is not a battery charger its a battery maintainer!!
Charge and load test battery- it may be not able to take a charge and need to be replaced You may a have blown fuseable link preventing alternator from charging battery