The previous few posters are on the right track.
Good work using your intuitions.

The battery pack is smaller than you think.
The batteries are less than 200 pounds, but then there's the stainless steel case, electronics, cooling system, etc... that gives you nothing back...

While your cell phone may charge to nearly 100% each night, and drain to maybe 10% to 20% during the day... It only lasts about 2 years.
Your cell phone also charges gently ( over 1-4 hours ) and discharges even more gently ( over 12-16 hours ).

Your FEH battery charges in minutes, and dis-charges in minutes, using about 100 amps at a time ( about 100 household light bulbs, about 1000 cell phones... ) and is meant to last about 15 years! Pretty amazing in my book.

Yes.... 100% to 0% charge would give to 10 miles of electric only driving.
Who's ready to buy a new $3000 battery every 2 years? Not me.

Ford built a very good machine in my book. A very durable one.

-John