Dead battery

shootin from the hip , your battery's no good ,a bad alternator will set a light on the dash , let us know what happens .

If its running fine with dead battery then alternator is good. So it should be fine to drive to get new battery anyway. Drive it for a while and do not turn it off until your at a place that sells batteries and installs them or your tools with you or drive back home without turning it off but if it dies on you and not battery power still then your alternator is bad too or bad connections.

I'm having the same problem for the second time in about six months

Mine left me set with zero indication of failure. (2014 Energi SE Luxury). Mileage was just at 45000 miles. It was the " starting battery" which in a normal car, is just the regular battery. Do not depend on the big battery pack to get you home under this condition. Call the Ford roadside assistance and have them bring you a new battery, or get it to the local dealer, let them replace it, and insist that they perform a system diagnostic to ensure that the visible links and other protective circuits aren't damaged. This is and should be covered under your warranty. (we bought ours used and got the extended warranty because parts are darn expensive) 2 years on, and no problems with batteries or charging system for the gas side of things. And other than cold temp low charge issues, zero problems with the EV side.

Sorry, answering from my phone. That's Fusible Links, not visible links.... auto complete got me