my auto zone now has a hand held load tester and volt meter.
you want to test the battery car off, its volts, and then load test it. if it fails the load test its done. unless its just weak form the alt not charging.
next they should check the battery voltage car running, this should be over 13 volts, some cars charge at 14 plus volts. mines any where from 13.3-13.9 depending on how much stuff is running in the car.
i did have a 03 gmc that took 3 new alt's till it liked one, every one was charging over 14 volts and the dash kept saying charging failure. 3 rd alt charged at 13.5 ish under 14, and it worked.
