I have a '07 Focus and had to replace the Motorcraft battery recently because the car failed to start. Even the radio failed to start because it said ‘low battery’. I took the battery to Autozone so that they can test the battery and they said it had a bad cell. Got a Duralast battery and the car has been running ok for a month. The only thing I notice is that on a really hot day, I first turn on the AC and I hear a small tttt(maybe that is normal and just being paranoid)
When I put that other battery, the guy at Autozone did a load test where he had me crank up the AC and turn on my headlights. The voltage of the battery went down from 14v to 13.something(dont remember). He suggested I have the alternator checked because he says the alternator might not be charging correctly.
I then took it to Advance Auto Parts and they did a load test. The test revealed the Voltage went from 14.25V to 13.62V. The guy there said that is normal and that I should expect the voltage to go down a little. I also took it to a mechanic and they did a test too and they said its ok.
My question is it if the voltage going down to the 13.62V should be normal under a load test?
I’m taking the car for scheduled maintenance on Saturday to a Ford dealership and was probably going to mention about the alternator. Thanks.