They can also test the alternator by giving it a high load and see if the alternator us producing the correct amount of amps under load , all while being in the car , for free . As long as the person nows how to use the quipment , they can normally tell you if it ' s the battery of the alternator . Edit I say the alternator spelling ? Because you say the battery slowly comes back up to voltage . A poorly working alternator could be having a tough time replenishing the power your car is drawing while at park low rpm . <| sep |> Yea this price is a bit high . They usually sell at 25 keys <| sep |> I feel like some of the lyrics to ' Dance to It ' are relevant here ' What do you want to hear repeatedly on the radio this year ? Something that sounds like the music I already listen to , but with different words '