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A Look At The Engineering Behind The 2021 Mustang Mach-E

https://jalopnik.com/a-look-at-the-engineering-behind-the-2021-ford-mustang-1839911078


A Look At The Engineering Behind The 2021 Ford Mustang Mach-E

The 2021 Ford Mustang Mach-E is a huge deal. It’s the first high-volume Ford built on a dedicated electric vehicle platform, marking what could be a major inflection point for the company as the world shifts away from gas cars and towards EVs. I had a chance to talk with some engineers about the Mach-E’s tech; Here’s what I learned.

The Ford Mustang Mach-E started out life as a compliance vehicle—something that Ford was putting together to meet government CO2 and California’s zero emissions mandate. But then came a shift—a directive from higher-ups that changed the nature of the program from something boring into an EV “Mustang.”

This turned the Mach-E into a sporty vehicle meant to take design cues from FoMoCo’s famed pony, and it meant the name Mustang would adorn a vehicle with an all-new dedicated electric-vehicle platform; a sizable, skateboard-style battery pack between the axles; and electric drive units in either just the rear, or in both the front and rear.

That’s at least the story I heard from the 2021 Ford Mustang Mach-E’s Chief engineer Ron Heiser, who walked me through how the new “Mustang-Inspired” electric crossover is set up.


The Motors

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The 2021 Ford Mustang Mach-E’s drive unit is similar to what’s found in some Teslas, Volkswagen’s MEB cars, the Porsche Taycan, and other EVs. It packages a permanent magnetic synchronous motor with a gearbox that has a roughly 10:1 gear reduction, and it integrates electronics including a power inverter that takes the battery’s DC current and turns it into AC for the motor.


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Ford offers two motor variants, a 210 kW (282 horsepower) one with a max torque output of around 300 lb-ft, and a smaller 50 kW (67 horsepower) one making 111 lb-ft of twist. The rear-wheel drive Mach-E gets the larger motor only, the all-wheel-drive model adds on the little 67 horsepower unit up front, and the GT has a large motor at both the front and rear axles.


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Rear-drive Mach-Es make a claimed 255 horsepower and 306 lb-ft of torque when equipped with the standard range battery (more on batteries in a moment); with the bigger pack, the torque number stays the same, but horsepower goes up to 282.

With the standard-range battery pack, all-wheel-drive non-GTs, which get the big motor outback and the small one out front, make the same power as the rear-drive cars (255 HP), but offer significantly more torque at 417 lb-ft. Mating those two motors of different sizes to the larger battery pack ups the power to 332 horses, but torque remains at 417 lb-ft. Finally, there’s the GT model, with a 210 kW motor in both the front and rear; This results in a targeted 459 horsepower and 612 lb-ft of torque.

Zero to 60 mph acceleration ranges from the “mid six-second range” for the rear-drive car with the heavier battery to the “mid three second range” for the GT.


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The first two pictures in this section show the smaller 50kW motor, and the second two (including the one directly above) show the 210 kW unit.

Ford says the motors are custom designed, and that the larger one cools its stator with oil, which is sent through an oil-to-coolant heat exchanger. The smaller motor, Ford told me, features simply a water jacket, presumably around the outside of the motor housing. According to Ford, special valving allows for the heat from the motors and power electronics to be used to warm battery cells (there’s also a resistance-style heater to help with that).

Notice the “hairpin” stator design, which is also found in the Chevy Bolt and Porsche Taycan. According to Porsche, compared to a traditional “pull-in winding” stator assembly method, this design allows for tighter packaging of copper, improving performance for a given size as well as cooling.



Drive Units With Coaxial Gearboxes

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The Mach-E’s two motors make up drive units that are bolted to the rear (or front and rear) subframes. The images above and below show one of the drive units (the smaller 50 kW one). As you can see, the motor is packaged with a number of power electronics, and it’s mated to a coaxial gearbox.


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The coaxial, single-speed gearbox bolts directly to the end of the motor, and sits right on the axle centerline so that it and the motor are packaged directly between the wheels. In fact, one of the CV axles powering the wheels actually passes through the rotor inside the motor in order to hook to the gearbox.

This coaxial setup, also found in the Jaguar I-Pace and the Porsche Taycan, is nice and compact, offering a number of packaging advantages compared to the parallel arrangement—in which the motor sends power through the gearbox either forward or backward to a parallel drive axle—found in a number of electric vehicles including all Teslas.


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You’ll notice that the power electronics are packaged on the same subframe as the drive unit. Based on my discussion with a Ford engineer, the first case just above the stand-in subframe is the charger, the case on the top left is the power inverter, and the little box on the top right is the DC-DC converter charged with converting high-voltage power to 12-volt power for interior accessories and lights. Here are some closer images of those electronics; you’ll notice that they all feature coolant ports:


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The Suspension

At the debut on Sunday, I slid under some Mach-Es to try to catch a glimpse of the hardware packaged in-vehicle, but I couldn’t see much, as the entire underbody is covered in aerodynamic shielding. Still, the photos above and below show the Mach-E’s independent rear multilink suspension with what looks like a stamped steel lower control arm, and you can see a bit of the drive unit’s cast aluminum case towards the center of the axle.

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Up front, the Mach-E features a MacPherson suspension design, with what looks to be an aluminum lower control arm and an aluminum steering knuckle.


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Here’s another angle. That black shaft with the large rubber CV-boot is the axle that transmits power from the coaxial transmission to the wheel hub:

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Here’s another angle, which shows the steering tie rod (which also features a black accordion-shaped bellow) in the foreground and the axle shaft in the back:

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I tried to get my camera deep into the suspension bits to have a look at where the drive axle actually enters the gearbox, but the photos below are the best I could do. Notice how the drive unit looks to have some sort of black cover over it:

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The Body And Battery Pack

Ford didn’t talk much about what makes up the Mach-E’s body structure, and in fact, the company hasn’t even released a curb weight figure yet. What I did learn at the reveal is that the body is predominantly steel, and with the larger of the two battery packs, I bet it weighs a lot.

That larger, “extended range” battery pack is shown above. It features a 98.8 kWh capacity thanks to 12 battery modules (which are not all the same size) with a combined 376 cells. The smaller “standard range” pack has only 10 modules and 288 lithium-ion cells, for a total of 75.7 kWh of capacity.

You’ll notice at the far left side of the image above that there’s actually a second tier. On extended range Mach-Es, those two modules on the second level sit under the rear seat. The standard-range cars simply have a void in that location, as the two battery sizes share the same case.

The cells, which are pouch-style lithium ion cells from LG, are arranged in “3P96S” and “4P94S” configurations, meaning the smaller pack has three parallel sets of 96 cells arranged in series, while the large pack has four parallel sets of 94 cells arranged in series. Overall system voltage is close to 400 volts.

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The battery pack itself is a large cast aluminum unit, with some sorts of extrusions welded to the bottom of the tray, Ford’s battery engineer told me. The pack is bolted to the chassis from below.

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The pouch cells in the pack (one of which is shown below) sit upright in the tray, with each sitting against aluminum fins that pull heat down to the heat exchanger below.

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I must admit that I’m not entirely sure how the battery cooling setup works on the Mach-E, and Ford engineers were very light on details. Is there a cooling plate below the battery pack floor? Or does each individual module (or perhaps each row of modules) have its own cooling plate?

I’m not sure, though I could tell based on Ford’s display that the second tier of modules had its own cooling plate, which makes sense:

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As for the first layer, I don’t know how the heat exchanger is set up, but I bet the pack floor is a big heat exchanger, with coolant running through it, taking heat away from the batteries and dumping that heat out at a chiller. (The chiller is just a coolant-to-refrigerant heat-exchanger that uses the condenser and compressor already in there for the air conditioning).

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As I understand, there are only two heat exchangers in the front of the vehicle: A Condenser and a radiator. The motor, battery, DC-DC converter (which changes high-voltage to a lower-voltage for in-cabin use), charger, inverter, and other power electronics are all part of a main “low-temperature” cooling loop using presumably some sort of glycol-based coolant.

There’s a bunch of valving that allows the motor to warm up the battery and there’s a resistance heater to aid on that front. Plus, the valving allows for the batteries to dump their heat into the refrigerant in the chiller in the AC system. I’m definitely looking forward to learning more about the cooling system setup.

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Range estimates for the standard pack are 210 miles for the all-wheel-drive non-GT and 230 miles with the rear-drive model. Extended range non-GT Mach-Es can drive an estimated 270 miles when equipped with all-wheel drive or 300 miles in rear-drive form, while the GT can go an estimated 235 miles without running out of juice.

The base “Select” trim, which is offered with the standard-range battery only, offers charging at 115 kW, while other trims offer 150 kW charging. Ford discusses charging rate in its Mach-E press release, writing:

With peak charging rate of 150 kW, the Mustang Mach-E with an extended battery and rear-wheel drive can add an estimated average of 47 miles of range in approximately 10 minutes while charging on a DC fast charging station.⁷ The standard-range Mustang Mach-E is estimated to charge from 10 percent to 80 percent in approximately 38 minutes while charging on a DC fast charging station.

But you don’t have to use a plug to re-charge the Mach-E; Like all EVs, the motors can be used as generators to shove electrons into those battery cells. Ford says it offers various levels of brake regeneration, including true “one-pedal driving,” which means letting off the accelerator yields a strong deceleration as the car uses the vehicle’s kinetic energy to charge the batteries.



The Doors And Aerodynamics

The Mach-E has some pretty interesting aerodynamic features. Notice in the photo above that there appear to be literally zero grille openings. That big mouth in the front may look grille-like, but it’s fake. Down below, though, there are six grille shutters:

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Behind those grille shutters sit the condenser and radiator. And based on my conversation with a Ford rep, the two sets of grille shutters do not function independently, sharing an actuator (I’ve reached out to Ford to confirm this).

The point of the grille shutters (which you also find in cars with internal combustion engines) is to avoid producing unnecessary drag by sending airflow through a rather un-aerodynamic engine bay. If the motors, batteries, electronics, or passengers don’t need cooling, there’s no need to send air through the heat exchangers and incur a range penalty.

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Another fun aero bit is the opening in the lower corners of the front fascia, which is meant to create a curtain around the wheel openings.

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Ford described the advantages of an “air curtain” in an F-150 press release back in 2015, writing:

It’s not obvious to the eye, but rotating wheels are a major source of drag. Enclosing the wheels in skirts to smooth the flow isn’t necessarily practical or attractive – especially on a vehicle as hardworking as F-150. So Lietz and team adopted a different approach.

Horizontal slots underneath the headlamps channel air from the front of the truck through ducting to openings in the wheel wells – directing it across the outer surface of the wheel and tire. The wall of high-speed air works much like a skirt to reduce drag, while still leaving the alloy wheels fully exposed.


Another aero enabler is the ridiculously flat under-floor. Here’s the front:

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Here’s the center, which is just the bottom of the flat battery pack:

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And here’s a look from behind:

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Then, of course, there are the doors, which don’t have traditional handles or buttons. In fact, the rears don’t have a handle at all, and Ron Heiser says this could provide an aero benefit since a traditional handle might cause flow from the side of the vehicle to detach.

Heiser says in our interview above that there are actually supercapacitors in the doors to allow for a user to enter the vehicle even when the battery is dead. If the super capacitors don’t work, Heiser told us, there’s another way of entering that involves accessing the frunk and jumping the battery.

As for getting out of the vehicle when there’s an electrical failure and the electronic door latches no longer work, the front two doors feature tiny handles that you can pull back a bit to actuate the electric latch or pull back farther to actuate a mechanical release.

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Anyway, that’s about all I know about the 2021 Ford Mustang Mach-E. Ford uninvited me to their tech deep-dive, so my time with engineers was limited, and even when I did talk with engineers, they didn’t seem to want to go into depth. So we’ll have to wait a bit before I can get into the nitty gritty.
 

Popeye

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This info is an amazing find! I wonder if there is a way you can disable AWD and use RWD only. The range takes a major hit when running the AWD, and there are actually 2 motors, one for the front and one for the rear. So I wonder if you can disable the front motor to optimize its range.
 

RyZt

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This info is an amazing find! I wonder if there is a way you can disable AWD and use RWD only. The range takes a major hit when running the AWD, and there are actually 2 motors, one for the front and one for the rear. So I wonder if you can disable the front motor to optimize its range.
The front motor adds weight. I'm no expert, but I suspect that's where the majority of range loss come from. Therefore, I doubt that the ability to turn off front motor would be of any help.
 

Falc'man

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This info is an amazing find! I wonder if there is a way you can disable AWD and use RWD only. The range takes a major hit when running the AWD, and there are actually 2 motors, one for the front and one for the rear. So I wonder if you can disable the front motor to optimize its range.
Ford have been quoted as saying that it is never a 100/0 or 0/100 torque split. Typically it's 30/70 and varies depending on circumstances.
 

frinesi2

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David Tracy does great tech writeups. Thanks for sharing.
 

Mister Mitch

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Impressive write up. Thanks for sharing.
 

w3rkn

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This info is an amazing find! I wonder if there is a way you can disable AWD and use RWD only. The range takes a major hit when running the AWD, and there are actually 2 motors, one for the front and one for the rear. So I wonder if you can disable the front motor to optimize its range.
It is not 4-wheel drive, it is AWD.

AWD already "disables" when not needed and uses what wheels are. That is why it is called AWD because it changes instantaneously as you drive..... just like you are asking.

If the front is not needed, then it won't use the front as much, depending on how it's programmed, etc.
 

wesk1318

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Any idea if the electric motors/components are Ford designed/built? Or are they sourced from Rivian or another company?
 

buzznwood

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Any idea if the electric motors/components are Ford designed/built? Or are they sourced from Rivian or another company?
Will have to wait for someone to tear one down, but I would guess it is probably an off the shelf part from someone like bosch.
 

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