We bought a brand new alternator and battery and the battery light keeps coming on. I have a 2011 GMC Acadia. The alternator isn’t keeping the battery charged but it is brand new and I had them test it twice and they said it’s good. I don’t understand. Once the battery goes dead the car won’t start. If it’s charged it starts. Please someone give me a opinion. Thanks.

this is not helpful because as I stated, the alternator ans battery are new and was tested before they were purchased, the alternator is not keeping charge, in return it is draining the battery. We I charge the battery it cranks right up but still the alternator will not keep charge.

Check all connections and use a volt meter at the battery and the main feed at alternator big wire and see what voltage you have