What's a good kw per mile range (on highway) for extended range battery?

[cyberman]

Energy required is proportional to the cube of the speed.
Regen is only helpful when it is being used in lieu of friction brakes. It is not responsible for better low speed efficiency.
Energy is measured in kWh, power in KW.

This isn't quite right. The force f holding back a vehicle, the so-called Road Load, is well known to be modelled accurately by a quadratic equation where the variable is the speed of the vehicle xdot:
f road = a + b xdot + c xdotsquared + m g sin(theta)
where:
a is a constant and corresponds to the constant rolling resistance of the vehicle, especially the tyres;
b is a constant that corresponds to the velocity dependent rolling resistance;
c is a constant that corresponds to the air resistance of the vehicle;
m is the mass of the vehicle;
g is the force of gravity;
theta is the angle of the road surface with respect to the horizontal; on a flat road theta is zero and sin(theta) is zero meaning there is no change as a result of going uphill or downhill.

So, the Road Load is a little dependent on vehicle speed through b and strongly dependent on the speed squared through c. It's this drag on the vehicle proportional to speed squared that kills the efficiency of any vehicle as the speed increases.

For my own interest I recently put together a spreadsheet of this equation for my Mach E AWD with Standard Range battery:

Road Power Load calculation
		g =	9.81​		m / s2
			f road =		a + b xdot + c xdotsquared + m g sin(theta)
Coefficients			Kinetic energy =	1/2 m xdotsquared
a	31.9​	lbf
b	0.3973​	lbf/mph
c	0.01956​	lbf/mph**2
Vehicle mass
AWD SR	2640​	kg
Driver	67​	kg
				1 lbf is equal to:	4.4482216​	N
Speed, xdot	mph	m / s	F road / lbf	F road / N	P road / W	P road / kW
	0​	0​	31.9​	142​	0​	0.0​
	10​	4.470272687​	37.829​	168​	752​	0.8​
	20​	8.940545373​	47.67​	212​	1896​	1.9​
	30​	13.41081806​	61.423​	273​	3664​	3.7​
	40​	17.88109075​	79.088​	352​	6291​	6.3​
	50​	22.35136343​	100.665​	448​	10008​	10.0​
	60​	26.82163612​	126.154​	561​	15051​	15.1​
	70​	31.29190881​	155.555​	692​	21652​	21.7​
	80​	35.76218149​	188.868​	840​	30045​	30.0​
	90​	40.23245418​	226.093​	1006​	40462​	40.5​
	100​	44.70272687​	267.23​	1189​	53138​	53.1​
	110​	49.17299955​	312.279​	1389​	68306​	68.3​

Here is what a graph of Road Load (kW) versus Speed (mph) looks like:

There are lots of observations that can be made from the numbers and the graph. Here are just a few:
1. The numbers are all rather low down at 10 or 20 mph. This is just the rolling resistance of the vehicle.
2. The Road Load at 50 mph is 10 kW but at 70 mph it is twice that: 21.7 kW
3. At 100 mph the Road Load is more than 5x its value at 50 mph. Don't expect much range if you drive at 100 mph!

I hope some of the above is helpful. It's not an exact simulation but it does use real numbers for the Mach E AWD SR taken from a dynamometer (I think).

Sponsored

 

[babgvant]

That is very impressive for a GT/PE.

In our GT (not PE) we usually get ~1.8 to 2.0 in the cold and 2.3 to 2.5 when it is warm, but that is at ~72mph - not 80! Anything above 75 and we are back down to 2.0 to 2.2. Only time I have seen anything approaching 2.7-2.8 on a trip is when we stuck to side street and 45-55mph.

What is your secret?

Part of it is that I live in the midwest, it's pretty flat around here, some of it is probably related to changing the tires from the summer to a high-quality all-season.

I don't know what the elevation change is from Chicago to Cleveland, but I can't imagine it's that large. We got 3.0 m/kWh on the way out (by way of Ann Arbor) and 3.2 on the way back (or maybe the other way around), there was a tailwind on the 3.2 leg and I was pretty aggressive about sitting 1 to 2 BC bars off the back of semis in both directions (for science, obviously ).

 

[mkhuffman]

Part of it is that I live in the midwest, it's pretty flat around here, some of it is probably related to changing the tires from the summer to a high-quality all-season.

I don't know what the elevation change is from Chicago to Cleveland, but I can't imagine it's that large. We got 3.0 m/kWh on the way out (by way of Ann Arbor) and 3.2 on the way back (or maybe the other way around), there was a tailwind on the 3.2 leg and I was pretty aggressive about sitting 1 to 2 BC bars off the back of semis in both directions (for science, obviously ).

Also traffic has a big impact. If you run into some slower traffic, the efficiency isn't really what you are getting at 80 mph. Ideally, you would want to run the car at 80 mph with no slow slowing down, no speeding up, just maintaining the exact speed for a very long distance - like 50 or 100 miles. And no drafting! Then the efficiency should be more representative of what the car can really do at that speed.

I get 2.4-2.5 mi/kWh when I set the cruise on 80, but it is rare that I don't run into slower traffic. Very rare.

 

[HuntingPudel]

Efficiency is very particular to terrain. If you drive on a flat highway at 70 - 75 mph, you'll see very close to 3.0. If the road is gaining altitude, and then losing altitude, it has a big impact. You see absurd figures posted by people in Florida on flat roads, or Arizona. In upstate NY, your roads aren't flat, so I would expect 2.8 or so.

Any GT getting anywhere close to 3.0 at 70 on a flat, level road is highly unlikely (downhill, maybe). The GT nose has way too much drag. Those “air curtains” Ford touts are called “drag ducts” in most racing circles. The larger splitter on the GT also makes more drag than on the other models.

I have mostly flat and level ground on my commute and I don’t get anywhere near 3 unless it’s slow and go or a constant speed somewhere around 60 using the cruise control. I got low to mid 2s per KWh on my trip to/from WA, mostly on cruise control, with a max speed of 72 (much slower when it was snowing).

 

[Ken Josing]

Hello all,
Can anyone explain what good highway range should be on the extended range battery? took a 120 mile trip yesterday and paying attention the KW usage it seems like 2.7 miles per KW was about average if I was going 75 mph or less anything more than that and it dropped down to 2.2 to 2.4 Around town it seems to be in the 3.1 to 3.5 Is this normal use?

Everyone is different and the answer to your question will have different answers. Let’s take me for instance. I have RW drive and the ER battery. I’m old and drive in “Whisper” 100%, use one-pedal exclusively. In Ventura County California I travel at 72 on the freeways. I keep an excel file on all the charging/driving. To date on my 2021 I have driven 12,219 miles, used 3,461.92 kWh and averaged 3.53 miles per kWh. In the vehicle on the “My trips” this number is always higher than actual, usually 3.7/4.1.

 

[EELinneman]

Hello all,
Can anyone explain what good highway range should be on the extended range battery? took a 120 mile trip yesterday and paying attention the KW usage it seems like 2.7 miles per KW was about average if I was going 75 mph or less anything more than that and it dropped down to 2.2 to 2.4 Around town it seems to be in the 3.1 to 3.5 Is this normal use?

And, in colder weather, expect a significant reduction. Your utilization rate seems about the norm.

 

[babgvant]

Any GT getting anywhere close to 3.0 at 70 on a flat, level road is highly unlikely (downhill, maybe). The GT nose has way too much drag. Those “air curtains” Ford touts are called “drag ducts” in most racing circles. The larger splitter on the GT also makes more drag than on the other models.

I have mostly flat and level ground on my commute and I don’t get anywhere near 3 unless it’s slow and go or a constant speed somewhere around 60 using the cruise control. I got low to mid 2s per KWh on my trip to/from WA, mostly on cruise control, with a max speed of 72 (much slower when it was snowing).

Was that a PODH? It kind of felt like a PODH .

Unfortunately, I couldn't go further back than 30 days in the app, so had to roll with what I'd screenshotted before.

 

[River Rat]

Part of it is that I live in the midwest, it's pretty flat around here, some of it is probably related to changing the tires from the summer to a high-quality all-season.

I don't know what the elevation change is from Chicago to Cleveland, but I can't imagine it's that large. We got 3.0 m/kWh on the way out (by way of Ann Arbor) and 3.2 on the way back (or maybe the other way around), there was a tailwind on the 3.2 leg and I was pretty aggressive about sitting 1 to 2 BC bars off the back of semis in both directions (for science, obviously ).

All savings from drafting are lost when the semi's shreds a tire

 

[timbop]

I get 2.4-2.5 mi/kWh when I set the cruise on 80, but it is rare that I don't run into slower traffic. Very rare.

Aren't school zones a PITA?

 

[babgvant]

All savings from drafting are lost when the semi's shreds a tire

The 1-2 following distance is safe-ish, obviously you'll want to watch out for tires .

Sponsored