Beyond Fossil Fuels: Test Driving Mack's MD Electric

Mack entered the medium duty BEV market in March 2023 with the launch of a battery-electric MD model. It was unveiled at the National Truck Equipment Association 2023 Work Truck Show in Indianapolis. Last week, Mack dealers and trade media reporters got a closer look at the truck during a ride-and-drive event at the Sonoma Raceway in Sonoma, California.

Mack also revealed details of a new "truck-as-a-service" subscription program intended to make the transition away from fossil fuels much easier for even really small fleets.

Mack's MD Electric is offered in Class 6 (26,000 ln GVW) and Class 7 (33,000-lb GVW) configurations. Each is available with either a 2-battery or 3-battery setup, offering 150 or 240 kWh capacity. Mack's published range estimates of 140 miles for the 150 kWh configuration, and 230 miles for the 240 kWh version put the MD Electric squarely within 80% of its documented customer use profiles.

In fact, the North American Council for Freight Efficiency (NACFE) believes that nearly the entire medium-duty box truck market segment is, right now, ripe for electrification. That's about 380,000 vehicles, according to NACFE, representing a possible avoidance of about 7.7 million metric tonnes of CO2e or “carbon dioxide equivalent” annually.

Not only are weight and range limitation largely inconsequential for medium-duty trucks, the total cost of ownership (TCO) turns positive in a much shorter period.

“Light- and medium-duty are the ideal applications for [electrification] right now,” said Lydia Vieth, a research analyst in electrification and autonomy at ACT Research. “Our analysis already shows there’s a positive financial case for switching from diesel to electric.”

Based on some generalized and simplified calculations, Mack says the sweet spot where TCO turns positive on the MD model is about three years.

"The three year mark is where you get the positive TCO," said Mack vice president and e-mobility business unit leader, George Fotopoulos, speaking at the Sonoma Ride and Drive event. "Obviously, this is going to grow through the fourth and fifth year marks, and the delta is going to get better all the way out through 10 years."

Mack based its assumptions on factors such as 30,000 annual miles, $40,000 IRA tax credit, equal maintenances cots between diesel and electric, slightly higher insurance costs, a 9% interest rate on financing for a diesel and energy costs of $0.12/kWh versus $4.00 diesel.

Operational Considerations

Mack believes the MD Electric will be a one-for-one replacement for existing diesel trucks in most applications. Fleet will not need two or three electric MDs to replace a diesel because of weight and range restrictions or availability constraints imposed by charging times.

Mack studied its existing customer use profiles while building the business case for the MD Electric. It found that 80% of its customer base currently running diesel MDs ran less than 250 miles a day, while 50% of that group ran less than 125 miles per day.

Further, they tend to stay within those mileage silos. They do not tend to run 125 miles one day and 250 miles the next day. That makes spec'ing a truck for a given run much easier.

Unlike a diesel truck, which can be fueled anywhere at any time, planning to integrate electric trucks into the fleet takes some planning. Mack representatives will analyze existing use patterns and make recommendations based on individual routes in some cases. If the MD Electric's capabilities fit within the parameters, it's a go.

"Each one of our customer projects starts with an advisory services session where we get an idea of the customer's short- and long-term aspirations, what their current utility infrastructure looks like, and to get an understanding of what their operational goals are," said Ryan Saba, Mack's energy solutions manager. "And then we make recommendations based on what those goals are."

Of course, some contingencies are built in for weather, terrain, and payload. Mack says it has done extensive range testing, but stresses the published range estimates are just that, estimates — though probably pretty reliable.

"The range test that we do is based on diminishing loads -- out fully loaded, return to base empty," said Fotopoulos. "And since climate is a range-determining factor, we did our tests in the Greensboro, North Carolina area in ambient temperatures that are pleasant for human beings. However, cold or really cold weather could shorten the estimated range by 10-20% respectively."

That said, it's possible to add 10-15% to the truck's estimated range through recuperative or regenerative braking. That's impossible to predict until the truck is in the field, on the route and is driven by a fairly proficient driver. And overly aggressive driver could also cut the estimated range by not conserving energy or making full use of the regenerative capabilities.

Mack says the MD electric with the 150 kWh battery configuration will be just 1,000 pounds heavier than the diesel version. The 240kWh battery spec will weigh about 3,000 pounds more than its diesel counterpart. That extra weight could be a limiting factor for some fleets, but payloads would be considered early in the spec'ing process.

AC or DC? — Charging Options

The MD Electric comes wired with a CCS 1 connector, enabling both AC and DC charging. AC charging takes longer than DC charging, but many customer facilities, small manufacturers or bakeries, for example, my not have ready access to 480-volt three-phase electrical service. For that group, the more typical 240-volt service is adequate for AC charging.

The on-board AC charger is 19.2 kilowatts. A full charge, depending on the state of charge at the end of a run, would take 6-11 hours. On the DC side, Mack has an 80 kilowatt charging system so it can deliver a full charge in just a few hours.

An AC charging installation is less expensive and less complex, so it's ready option for fleets wanting to dip their toes into the electric pond, and it fits nicely into an application where the trucks are parked overnight and can charge during off-peak times.

"If you're a baker or a florist with two or three trucks, you operate six to eight hours a day, you're down the rest of the time, we're going to recommend a couple level two charging stations," said Saba. "It's an easier setup with lower upfront costs and far fewer "moving parts" if you will."

The Truck

MD Electric is available in 4x2 configurations, and it's well suited to the task. It features a short 103-inch bumper-to-back-of-cab (BBC) measurement and a ZF steering gear for sure steering and a sharp wheel cut in tight urban settings.

The battery packs are located between the frame rails in three locations: under the hood, under the cab, and directly behind the cab. Customers opting for the 150 kWh 2-battery configuration will not see the battery directly behind the cab.

"That's a safe position for the batteries, and it leaves the side rails free for truck equipment manufacturers to mount things they might need. It makes body mounting easier," noted Mack Trucks' senior product manager, e-mobility, Scott Barraclough.

The frame rails are clean for the most part, with just a small about of space on the right-hand side just behind the cab occupied by the 24-volt two cylinder reciprocating air compressor for the trucks air brake system. Over on the left-hand side lives the cooling module for the batteries, motor, and the power electronics.

The Drive System

The Volvo Group does not offer a "medium-duty" electric powertrain per se at this time, so Mack reviewed several available powertrain options at the onset of the project. The company decided ultimately on the Sea Electric solution. It was determined to be the best fit for its medium duty product in the North American market," Mack said.

The batteries are air cooled but that is supplemented with temperature monitoring software that will automatically derate the output of the motor or slow the charging rate a little if any of those components starts to get a little warm. There's no radiator up front under the hood, leaving that space open for improved air flow over the sensitive electronics. That also means there's no cooling system maintenance needed.

Further back on the frame, just forward of the drive axle is the motor. It's connected directly to the drive axle. There's no transmission. It's direct drive, but the axle has a 5.75:1 reduction. It can manage a top speed of 70 mph but there's still tons of hill-flattening torque available at startup.      

The top of the frame is flat, of course, and all the components are mounted below frame level. It's business as usual for the TEMs and body installers. Mack has also used existing bolt patterns where possible to minimize confusion during production and body installation. 

It's worth noting that the weight distribution of the truck has hardly changed. It's only 3,000 pounds heavier than a diesel. It picked up a little more weight on the steer axle than the drive axle, but customers won't have to worry if existing payloads are within spec for the truck.

In the Cab

The MD Electric features a stylish cab based on the Mack Anthem on-highway model that puts the truck back into medium duty. It's bound to attract interest from drivers on that count alone. The cab is roomy and comfortable with great visibility and really good ergonomics. On top of the optional air-ride main suspension, cab air suspension and an air ride driver's seat are standard equipment.

The dash panels and the instrument cluster remain largely unchanged from the diesel version. Gone, however, is the tachometer and some of the monitoring gauges, like oil pressure, coolant temp and of course, the fuel gauge.

That tachometer is replaced by a Power Meter. It illustrates graphically the level of current flow into or out of the battery. There's also a battery start-of-charge indicator that is sensitive enough to show positive results during regen braking. Drivers will immediately see the benefits of making the most of every deceleration event, too.

Driving the MD Electric

I had the opportunity to drive the diesel version of the MD a couple of months after it launched in March or 2020, just as the pandemic gripped America. It impressed me then, and that holds true for the electric version. I noted at the end of that test drive story that the MD was a truck perfectly suited for electrification. Mack wasn’t making any predictions at that time, but here it is; an all-electric MD.

It has an impressive list of standard driver comfort features, and I remarked at the time how quiet the cab was. It was right up there with most of the high-end Class 8 models I had driven, including the Anthem. I also really liked the steering and handling of the truck.

"The steering was a delight, and the handling on S-curves and less-than-perfect country roads was remarkable," I wrote. "It was right at home on downtown city streets. A right turn from the curb lane, owing to the length of the truck, required me to cross only slightly into the adjacent lane to complete the turn. Good marks for maneuverability."

During the ride and drive event, we drove a couple of laps around the track at the Sonoma Raceway. It wasn't a full length test drive, but it still left me satisfied. There were several grade changes to the track and some good twisting turns.

The recuperative braking was really nice. It has a three-position steering column mounted selector that allows drivers to choose the level of retarding power needed, much like an engine brake. Position three (full) was a bit aggressive for the lightly load trucks we drove, but with a bit of weight in the box it would be well on its way to being a one-pedal truck in the hands of a skilled driver.

Obviously, it was super quiet and really torquey. It's electric after all, and all BEVs share those attributes. But the MD is quiet to begin with. I think drivers will love working full shifts in relative silence.

And maybe the best news of all: the Class 6 version does not require a commercial driver’s license to operate for non-hazardous payloads.