I have a 2014 F150 5.0 with an intermittent alternator issue. It started with the battery going bad and since then I get an occasional battery warning symbol on the dash. I’ve replaced the battery and the charging system tested ok. I have a phone charger plugged into the cigarette lighter that shows voltage. It mostly reads 14.4 but a couple times it has read 13.3 or so for 30 minutes during my trips to work. Since I replaced the battery the battery alert has only come on two or three times in 2 1/2 weeks. The one time I had the phone charger showing the voltage it read 14.4 when I looked over at it. I don’t know if the voltage is good even when the alert is turning on or if it is a momentary drop in voltage that I haven’t been quick enough to see or test. My understanding is that below 13.5 volts is out of spec for my truck. I’m guessing the regulator is going bad but since I haven’t been able to test the voltage when it’s low enough to trigger the warning I hesitate to spend the money on a new alternator. What does this sound like to you?

 

Did you reset the BMS after you swapped the battery, or let the truck sit for ~8 hours to let the BMS "learn" the state of the new battery? Did you pull any codes? I assume the battery light should trigger a fault being stored.

For reference, I frequently see my voltage drop to ~13V at times due to the BMS adjusting charging voltages to maintain battery health. This has never caused a battery warning for me.

 

If your 30 minute drive to work is the longest drive you do and you have lots of other shorter drives, this can drain your battery.