I had this issue months after purchasing the car back in 2020. It was under warranty, so I had the battery replaced. It happened again today in January of 2023! The car was running fine the day before, and this morning it wouldn’t start. Battery showed 8V, so it drained overnight. Just had the car towed and the tow truck driver said this happens all the time. Every two years expect the battery to die. I haven’t seen a recall from Ford or any solutions for this problem. I’m looking into replacing the 12V with an Optima battery.
Suggest to not depend on that diagnosis. Most likely causes are either the 12 volt battery isn’t being charged properly (hybrid control-system problem), or 12 volt battery is draining overnight b/c something remains turned on. After you park, doors/windows closed, everything “off”, wait for a couple of hours, go back out and check if any lights are on, brake lights, glove compartment, interior, trunk, engine compartment etc.
I have had 2 Fords that ate batteries. One because of a weak alternator and tne short trips we were taking. The second because of heat. The battery would be fine to drive to… but an hour later, nothing. No lights, no crank, could not be jumped. If you live where is is hot most of the time… Florida, Arizona, Texas, it IS normal. Buy 36 month batteries with no pro rated life.
If the tow truck driver says its normal… it is because the driver has towed a LOT of these cars.