I figured out how to get an almost new battery to replace my poor 3.9kwhr - but I don't recommend it at all: a '97 F250 missed the fact that traffic had stopped; he did not miss me.
I've given Ford a lot of grief over their battery management (and rightfully so, I'd say) (and of course I'd say that), but even with a 90s era Big ol'Truck slamming almost straight into the back at ~35mph ... the crumple zone protected the battery: missed it by 2-3 inches. Insurance still totaled my sweet girl.
I expected my 2013 to last me for 15+ years. By then, all sorts of electric, nuclear, flying wonders would be available, and I would never buy Ford again.
Just as it was in 2013, nothing on the market today can match what the Cmax Energi was to me. All in all, in 5.5 years, I spent $2,606.52 total on everything for that car: that's all fill ups, all service, 2 tires... car washes.... Even with a reduced battery, that car was a good car.
So I bought a 2016. Missing a few of the features of my 2013 (I never did use the auto park), but I tested the capacity before buying, and it is a much more healthy 5.2kwhrs. (Of course, the dealership didn't have it charged for my test drive … how do you expect to sell a partially electric vehicle without selling the electric part???) (then again, that's Ford for ya).
I'm still in the Energi family, but I know a lot more now. This battery won't suffer like the last one did.
Oh, and be careful with junkyard batteries: my old one is out there somewhere. Use the cells, not the whole battery.