Ford Energi and miles per kilowatt hour

[DozerCSX]

Greetings,

As the previous owner of a Chevy Bolt, and current owner of a Ford Fusion Energi, I like doing EV calculations from an energy perspective:

 

- The efficiency discussion of autos should always be centered on ENERGY and not MATERIALS, i.e. “mpge” (miles per gallon equivalent) is silly, sort of like mphb (“miles per hay bale”); at the end of the day, it’s about kilowatts and kilowatt/hours, which hold across technologies.

 

- for the record, a gallon of gasoline contains about 33.7 kilowatt/hours of energy. My Chevy Bolt battery held 60 kilowatt/hours of energy. That’s roughly the energy of two gallons of gasoline. So think of a gallon of gasoline as essentially an energy dense but super flammable and dangerous battery! And this quick analysis shows how incredibly inefficient a gasoline engine is.

 

- the standard for full EVs is 4 miles per kilowatt/hour. My Bolt used to routinely turn in about 4.2 miles per kilowatt hour.

 

- interestingly, my 2020 Fusion Energi has a 9.6 kilowatt/hour battery - if I get 28.8 miles out of a charge, that is about 3 miles per kilowatt/hour. I find it fascinating that my Fusion Energi is only about 75% as efficient as a full EV.  I believe this is due to the inefficiencies in having a transmission in the energy path, simply dragging on the system. But your guess is as good as mine. Still, the math is what it is.

 

- from above, if a gasoline engine car gets 20 miles per gallon, that’s only 20 miles from 33.7 kilowatt/hours of energy from the gasoline - by the math, that’s a paltry 0.6 miles per kilowatt/hour! Incredibly inefficient when compared to either the Energi or a full electric vehicle. Our Energi’s are about 5 times more efficient, while a full EV is about 7 times as efficient.

 

Fun Stuff to dazzle your friends with.

 

[murphy]

When running in electric only mode you are dragging around a heavy engine that is dead weight. 

My 2021 Mustang Mach-E averages 3.7 miles per kWh.

[theterminator93]

Driving style has a tremendous impact on energy consumption. Higher speeds, faster acceleration and more intense braking that requires the use of the traditional friction brakes will increase energy consumption per mile. You also need to consider the actual energy used and not the total capacity of the battery when measuring - the 7.6 KWh battery in the 13-18s only has 5.6 KWh available for EV only miles. The 19-20s have 7 KWh available, owing to the 9 KWh battery. The extra 2 KWh is reserved for hybrid mode and battery safety margins.

 

When I did a battery draindown test this spring, I recorded 26.5 miles before the car depleted the "EV" portion of the HVB and switched to hybrid mode. It was a round trip to negate the effects of wind and elevation changes) and measured energy was about 4.95 KWh - 5.35 miles per KWh (or 180 MPGe). I kept my speed to a max of about 40 MPH and did my best to get 100% braking scores, so this is undoubtedly a best-case scenario.

Edited October 23, 2021 at 03:44 AM by theterminator93

[jj2me]

I'm unfamiliar with the derivation of EV's 4 mi./kWh. 

 

I'm also unfamiliar with the reserved "headroom" of the 9.6 kWh Fusion HVBs.  But for the 7.6 kWh 2013-2017 FFEs, there's 2.0 kWh not available for EV driving (EV/Auto use) on a fully charged HVB.

 

Assuming the 9.6 kWh FFEs also have the same 2.0 kWh headroom, that would leave 7.6 kWh for full EV use.  The monroney for a 2020 with that 9.6 kWh battery uses 26 miles for EV driving range.

Calculations:
Monroney: 26/7.6 = 3.42 mi./kWh
Observed: 28.8/7.6 = 3.78 mi./kWh

 

Assuming instead that the headroom is proportionally larger than what the 7.6 kWh FFEs', then that would be 2.5 kWh of headroom, and the calculations above would be 3.66 and 4.06 mi./kWh.

EDIT: Forget the following.  While true, it doesn't apply here because you didn't do any EV calculations that were derived from the 33.7 kWh figure, like MPGe or kWh/100 miles as listed on the monroney] 
Comparison calculations of gasoline cars vs. EVs need to adjust for the fact that the 33.7 kWh gasoline equivalent number is "in the tank" for actual gasoline burning engines vs. 33.7 kWh is what's seen at the wall for EVs.  For the Energi, which is supplied with a Level 1 charger, you need to adjust for the L1 72% charging efficiency.

Edited October 24, 2021 at 02:27 AM by jj2me

[jsamp]

On 10/21/2021 at 3:06 PM, DozerCSX said:

 

- interestingly, my 2020 Fusion Energi has a 9.6 kilowatt/hour battery - if I get 28.8 miles out of a charge, that is about 3 miles per kilowatt/hour. I find it fascinating that my Fusion Energi is only about 75% as efficient as a full EV.  I believe this is due to the inefficiencies in having a transmission in the energy path, simply dragging on the system. But your guess is as good as mine. Still, the math is what it is.

 

 

The 2019 and later Energi's have a 9.0kWh battery, not 9.6, but that doesn't change the calculation result a whole lot.  What does change it is you can't use the whole 9.x in the calculation.  You need to measure what you used to get that distance.  If your 28.8 miles is from 100% to the switch to hybrid mode, that would be ~7.0kWh, which would give you a result of ~4mi/kWh.  The best way to measure is to use a trip odometer and do a test where you don't use any gas.  Use the miles and kWh reported by the trip odometer to do your calculation. 

 

And yes, the ~2.0kWh reserve is the same as the old 7.6kWh pack.  1.5 for hybrid mode and .5 for charge buffer at the top end.  This was confirmed by some posters here on this site who did the full charge drive test.

 

For me in my 2015 with the 7.6kWh battery I can get as much as 6mi/kWh if it is all low speed backroad driving with few stop-starts.  On the freeway it is closer to 4mi/kWh.  Can be even less if you have a lead foot.  YMMV

[DozerCSX]

Here's a simpler view: the information screen does the validation on the fly. In this picture it shows 13.3 EV miles, and 3.1 kWhrs used, which computes to 4.3 miles/kWhr (this is my flat, City roundtrip commute to work) Pretty darn good for a 4000 lb Fusion!

Edited January 6, 2022 at 09:36 PM by DozerCSX
info update