Bad Battery?

[Gene K]

I have a 18 F150 3.5 Ecoboost with start/stop system and AGM Battery. The system doesn't always keep the battery 100% charged because of fuel economy programming designed to reduce alternator drag.

For the last 3 days the start/stop system has refused to function. After one hour driving I pulled over and cut off the truck and accessories and put the truck in Engineering Mode to check voltage. The voltage was 12.2v with engine off which my references list as 40% charged for an AGM Battery. The voltage registers 14.0v with engine running.

I think the battery is bad.
Opinions?

Truck has 10 months of bumper to bumper - free battey replacement -warranty left.

 

[samven]

You could take it in and have them test it but I have noticed that just turning on the key will drop a good battery that was sitting at 12.6 down to 12.1 or 12.2. The easier route may be to put a charger on and make sure that you are getting it charged all the way up and then retest it to get a baseline. I notice that I need to put my battery on a charger every couple months to keep it starting strong even though the shortest trip I ever make is 22 miles its just not enough to make up for the parasitic draw and the start.

 

[MNgopher]

What reason does the truck give you for not engaging stop start when you think it should?

My 16 F150 will give the generalized reason on the screen in the dashboard. ( I have a 2.7 that had start stop back to 15)

Forscan can show you the detailed exact reason.

 

[Gene K]

What reason does the truck give you for not engaging stop start when you think it should?

My 16 F150 will give the generalized reason on the screen in the dashboard. ( I have a 2.7 that had start stop back to 15)

Forscan can show you the detailed exact reason.

Double Palm Plant Moment!

Until you mentioned it I had forgotten all about the option in the menu to leave Auto Start/Stop as the monitored function. I never use it. Usually on trans temp or instantaneous fuel mileage bar.

 

[Wolf359]

I have a 18 F150 3.5 Ecoboost with start/stop system and AGM Battery. The system doesn't always keep the battery 100% charged because of fuel economy programming designed to reduce alternator drag.

For the last 3 days the start/stop system has refused to function. After one hour driving I pulled over and cut off the truck and accessories and put the truck in Engineering Mode to check voltage. The voltage was 12.2v with engine off which my references list as 40% charged for an AGM Battery. The voltage registers 14.0v with engine running.

I think the battery is bad.
Opinions?

Truck has 10 months of bumper to bumper - free battey replacement -warranty left.

That reference list is for a battery at rest at 70 degrees with no load. As mentioned above, take the battery out and put it on a charger then measure the voltage after the charger is disconnected for a few hours. That voltage should match up to the state of charge chart. I did that to one battery and after I connected it to the car, the voltage dropped .3 volts. Your battery could be fine. Get it load tested.