2014 3.5 na Charging Issues

[Rckid143]

Long time listener, first time caller.
I have a 2014 XLT 2wd 3.5 135k that I've been having some slight charging issues with.

Preface is when driving in snow or heavy rain the battery stops charging, voltage drops eventually to ~11.5v and eventually the alternator starts charging again. When it does this the vehicle load sheds as id expect. It will do this for 5-10 minutes then eventually settle down and charge like normal (13.9-14.1v)

I was attributing this to a worn belt/tensioner.

Last week I took a trip, 3 hours 200 miles. Half way into the trip the voltage dropped to 12.5 and stayed there. Stopped for gas and voltage came back up to 13.9 for a few minutes then back to 12.5.

Same behavior on the 3 hour drive back home.
I did not notice any load shedding.

I've never had any warnings or codes pop up from this, but it's slightly worrying as I'm taking a 900 mile road trip this weekend.

Any thoughts?

 

[peterk9]

Welcome to the Forum.
It's just a guess but I'd say that the issue is with the alternator. If the belt is slipping, then it would affect the alternator's performance. Have yo changed the serpentine belt? Does it look frayed/worn?

Peter

 

[Turdle]

How old is the battery?

 

[Rckid143]

Welcome to the Forum.
It's just a guess but I'd say that the issue is with the alternator. If the belt is slipping, then it would affect the alternator's performance. Have yo changed the serpentine belt? Does it look frayed/worn?

Peter

Belt is original, and slightly worn. I attribute the belt squeal when wet and changing state from not charging to charging (when driving in snow or heavy rain). I plan on changing belt and tensioner asap, I've had the parts for a few weeks.

How old is the battery?

Definitely not new. At least 5 years old. Resting voltage seems to live around 12.1-12.2.
Old battery made me wonder if on a longer trip does the charging strategy determine it needs to charge at lower voltage based on some calculated SOC.
For example, many newer GM vehicles charge at lower voltage to increase mpg as part of their load shedding, but I've never experienced that with a Ford vehicle. I've also never had any issues with capacity or slow starting.

 

[Rckid143]

Update:
New belt and tensioner fixed the belt squeal and not charging. Drove through multiple flooded roads in Myrtle Beach today and not a single issue.

The low voltage charging is 100% intentional. After a few hours voltage dropped from 13.9 steady to 12.5-12.7v for the rest of the trip. Going down hill, off throttle on the overrun voltage goes back up to 13.9v.

 

[Ironworker40]

12.1 - 12.2 volts at rest means the battery is bad. Should be 12.6or higher. I would put another battery in it and see how it acts.
How do you know when its sheding loads?