I recently traded my 2010 5.4 in on a 2012 Ecoboost. Had a battery problem with an accessory, now removed, and have been monitoring battery voltage with a digital gauge that plugs into the lighter socket since. I just turned 1000 miles.

The battery seems strong, I see 11+ volts on startup. After start the voltage goes up to 14.25 volts or so. After a while I will see the voltage drop to about 13 volts. I assume this is after recovering from startup load. On subsequent starts this behavior repeats itself.

I have verified the voltage readings with a handheld meter so I think it is correct. I also did a search online that did not provide any help.

Is this normal behavior on this model? Or do I have a possible regulator issue? Or something else?

Thanks
Rod

 

Seems the charging system is operating correctly. If anything the battery itself maybe weak if it was deep cycled too often. Standard batterys don't recover well from being deep cycled often. If anything have your battery load tested to verify it's life.
I had a similar situation on my 2010 where the battery had been run down during the winter -- of course the colder it gets the worse it is on the battery. Took into the dealer --- they load tested it and had to replace it under warranty.

 

New Batttery, replaced under warranty.

 

Battery voltage is dictated by battery temperature algorithm in the pcm. As the battery temp increases, voltage decreases.

 

Good stuff -- I suspected that would be the case.

 

hmmm -- interesting ?!?!?
Care to expand on how the pcm monitors the battery temperature and dictates the battery voltage based on temperature ?

 

Key words are algorithm. Perform a bunch of tests you can predict battery temp off coolant temp and ambient air temp. During testing you measure actual battery temps and adjust the algorithm parameters to perform best in all operating scenarios. It is more accurate than you would likely guess.