Image source: Ford Motor Co.
Remember when Chevrolet showed the zoomy Camaro-inspired Volt concept car that made the EV world lose its mind, only to roll out a disappointingly dull production model saddled with an interior seemingly supplied by RubberMaid?
Ford has gone the opposite direction with its upcoming Mustang Mach-E EV, which started life as what Ford terms a “compliance” car. That is, a palatable EV built to comply with California’s mandatory electric car sales. As such, it was seen as little more than an electrified Focus economy car.
But Ford executives recognized that electric car components still cost more than combustion engine components, and that if customers are going to be asked to pay more, the manufacturer should deliver something more inspirational for the money.
The Mustang Mach-E is Ford’s solution to this challenge, explained Darren Palmer, Ford’s global product development director for battery electric vehicles. Most EVs until now have been tall vehicles, with high prismatic pouch battery packs stowed beneath the floor contributing to the upright layout.
|Darren Palmer. Image source: Ford Motor Co.
This is an area where Tesla’s use of AA-like cylindrical 2170 battery cells rather than prismatic cells provides an advantage. Those smaller cells can be packaged beneath the floor without raising it to SUV-like heights. Ford wanted to use prismatic packs, but didn’t want them to be so intrusively tall that they would undermine its plans for a sporty looking Mach-E.
The solution was a partnership with supplier LG Chem to develop new prismatic pouches that are shorter in height but wider, trimming the cells’ height to 5.9 inches (150 mm). These shorter cells are suitable for use in a wider array of vehicles than ones that would only fit in tall vehicles, boosting their potential for high volume, Palmer said.
“Should one car be more popular than the others we can switch between them,” he pointed out. This flexibility increases the likelihood that Ford EVs will find customers in one vehicle segment, if not another.
“That gives confidence to our suppliers,” said Palmer. “When they are nervous, they give us prices that are not good.”
Ford and LG Chem negotiated a deal for battery prices that are so aggressive that Ford raised its sales forecasts for the Mach-E. That put different pressure on LG Chem, which now had to worry about making enough cells rather than being stuck with inventory. Nevertheless, “we convinced them to keep the price,” he recalled.
Image source: Ford Motor Co.
Ford apparently believes that customer concern about battery pack longevity remains a potential obstacle to purchase, so the company will apply an 8-year, 100,000-mile warranty to the Mach-E’s battery.
Ford made another key decision on its motor technology, selecting permanent magnet motors rather than induction motors for the Mach-E. Palmer described first encountering the astounding power of small permanent magnet motors in an electric radio control helicopter.
“You have a motor that is like one inch across that has a ridiculous amount of power for the size of it,” he said. The challenge is metering the power from such motors. “You have to carefully control it; that’s where the skill is. How smoothly you do that is the characteristic of the car.” The finesse that is possible depends on the number of coils built into the motor, as increased coil density provides more granular control of the motor’s movement.
Permanent magnet motors are also more efficient than induction motors, which is driving the industry to the same solution, Palmer said. “Others who started on induction are moving to permanent magnets.”