I replaced my battery in Feb 2015, the alternator last month Oct 2015, because headlights seemed to get less bright while driving at night. I have almost 168K miles on original alternator. Worked fine for a couple weeks and then things started getting weird. Battery indicator needle spikes to high, CHECK CHARGING SYSTEM warning comes on, ABS light and traction control light flash. I think maybe I got a bad alternator from AutoZone. Belt is good (replaced less than 2 years ago), all pulleys good, all connections good, no corrosion, secure, so I am guessing I got a faulty alternator. I saw in threads elsewhere with things like 'Ford did not engineer the grounds right...you need to add additional grounds to the system'...but no definitive answer to flickering headlights and CHECK CHARGING SYSTEM warning problems.