A Pegasus bus using the Zeus Z-19 Power Platform is expected to allow 5,000 pounds more payload capacity. That could mean 42-48 passengers, compared to the standard 30 in a Type A-2 school bus. -...

A Pegasus bus using the Zeus Z-19 Power Platform is expected to allow 5,000 pounds more payload capacity. That could mean 42-48 passengers, compared to the standard 30 in a Type A-2 school bus.

Photo: Zeus Electric Chassis

School districts seeking viable options may be disappointed with the limited number of battery-electric (BEV) Type-A school buses.

That’s not from a lack of interest from school officials or due to any shortfall of effort from bus body upfitters. School administrators, in fact, have driven much of the BEV adoption over the last three decades. That initial demand for electric school buses found its epicenter in California.

“Well, when I worked with the school district, we were always considered to be on the leading edge when it came to electric school bus adoption,” says John Clements, retired director of transportation for Kings Canyon Unified School District in California’s San Joaquin Valley.

Known in school transportation circles as the “Electric Bus Evangelist”, he points even further back to Ralph Knight, whom, according to Clements, was the original “electric bus guru” at Napa Valley’s Unified School District. “He was the pioneer because he actually had the first electric school bus back in the 90s,” says Clements.

In his 39 years as a school transportation professional, Clements has been an advocate for clean school bus technologies and operational techniques as a strategy for protecting children’s health. He led his department to receive grants totaling more than $10 million in funding, helping to demonstrate the feasibility of zero-emission, battery electric school buses in the KCUSD fleet operations.

“I had to fight to get the funding for the first electrics that were on the block, and I got that funding little by little, but then we had a failure at the manufacturing level,” Clements mused. “That's what happened on that first EV bus that I had built in 2011. NHTSA came along and said you should crash test that vehicle because the batteries are hanging on the sides, and they're not caged. And after all our efforts, that manufacturer declined to agree to the testing.”

Clements explained that he took his funding and the Trans Tech body he had originally specified and worked with Motiv Power to integrate their nickel sodium chloride battery system to convert four gas-powered Ford E-450s into electric buses.

“I actually went to see the Ford cab and chassis being taken apart, and the electric power system being installed,” says Clements. “And then they tied that in with the Ford braking system and the Ford radiator and Ford hydraulics for the power steering. Then the upfitted chassis would be shipped to Trans Tech for the body installation.

“I had Motiv’s second bus off the line because their first one was a shuttle bus. In many ways, they cut their teeth on my four school bus initiative.”

Clements describes his collaboration on the design and building of these early electric buses with affection and maybe a little nostalgia, but he observes that for any school system trying to obtain a Type A school bus, the puzzle-like complexity of such an undertaking remains.

“Today, folks are still starting with a gas or diesel platform and trying to make an electric Type A bus out of it,” says Clements. “It’s not optimal and I would have hoped things would have progressed further by now, particularly in this environment of BEV fervor.”

Limited School Choice

Thanks to folks like Clements, a lot has changed in the ensuing years and progress has been made, particularly with larger buses. However, Clements’ observation, at least when it comes to Type A school buses being a slow-moving wave, appears to be spot on.

“From a school bus standpoint, I think all the bus OEMs have been developing BEV products to bring to market for the last four or five years,” according to Joseph D’Urso, vice president of Toronto-based City View Bus Sales & Service, a bus dealership serving education, health care, and public transportation markets. “There are conventional electric Type C buses, and there are electric Type D buses which are only used in about 10% of applications. The higher sales volumes in these two categories have spurred on the more rapid development of electric versions.”

D’Urso suggests that smaller Type A-1 and A-2 school bus offerings, which are very similar to shuttle buses, have been slower to hit the market, because they are a lower-volume vehicle. He estimates that these smaller buses, with capacities of up to 26 passengers, have been in development for roughly the last two or three years.

“So now we’re seeing inquiries for these smaller electric buses starting to pop up more often and those require partnerships with third-party upfitters because the non-electric chassis for Type A school buses and shuttle buses are most commonly sourced from one of the big three, usually from either GM or Ford,” says D’Urso. “And GM and Ford don't currently offer an electric powertrain.”

Referring to Ford E-450, Ford Transit, Chevrolet Express, and the GMC Savana, D’Urso explained that all are solid chasses that have been around for years with periodic technical updates to the powertrain, so electrifying them seems logical, because they've been proven.

“It's the upfitters ability to package the battery pack and engineer the electrification which is the challenge,” D’Urso says. “And there is a lot of engineering involved in converting a gas or diesel vehicle into a truly functional BEV.”

Collaboration Yields Something New

A recently announced collaboration between two companies provides one way to approach the engineering challenges that are endemic with converting gas and diesel platforms to electric. The stated intent of their alliance is to change the trajectory of Type A school bus development, performance, and reliability.

Zeus Electric Chassis, Inc. is a White Bear Lake, Minnesota-based company that has engineered a versatile, severe-duty BEV cab and chassis dubbed the Zeus Z-19 Power Platform. Pegasus Bus Company is a Dunkirk, Ohio-based company spearheaded by veterans in the school transportation and manufacturing industries.

Together, the companies will use the Zeus Power Platform to deliver a Type A-2 school bus. The ground-up design of the Zeus Z-19 cab and chassis is purpose-built and optimized for bus body installation and system integration.

“Its robust frame rail construction and purpose-built electric chassis makes the Z-19 different right out of the gate,” says Brian Barrington, president of Pegasus Bus Company. “Honestly, those two things alone make it far better than what's currently out on the market.”

With all-wheel-drive, independent suspension and a gross vehicle weight rating (GVWR) of up to 19,500 pounds, its electric motors are expected to generate 290 horsepower and 2,040 foot-pounds of torque. It’s said to be able to operate in inclement weather, on challenging topographies, and should be able to transport a payload of up to 8,000 pounds within a standard range of 150 miles.

“Compared to the 14,500-pound GVWR of the standard gas or diesel conversion models on the Ford and GM platforms, the Z-19 gives us 5,000 more pounds of payload to play with,” says Barrington. “Most Type A-2 school buses will hold up to 30 passengers and we’ll probably be able to get to 42, maybe even 48, with the Zeus Power Platform.”

The Z-19’s Lithium Ion NMC batteries sit protected between the chassis frame rails and have an expected life span of approximately 3,000 charging cycles, which should provide school bus fleets with between eight to 10 years of service depending on their duty cycles. The system automatically heats and cools the batteries to maintain optimal performance. The charging configuration is designed to support Level 2 and DC fast charging, and the system has export power capabilities to suit customer needs.

According to Bill Brandt, chief revenue officer for Zeus, seamless system integration was at the forefront as the company designed the Z-19.

“Until now, everybody that's been upfitting a bus body on a modified gas or diesel chassis has had challenges converting gas- and diesel-engine-driven components, like HVAC, air compressors and hydraulics.” says Brandt. “In a traditional bus, the HVAC and all other subsystems are driven off the engine, so when you remove the engine, you remove the power source. Upfitters often try to repurpose some of the OE hardware or try reengineering their own solutions.”

Brandt insists that simple and versatile systems integration was a central issue at the start of the Z-19’s design and remained so throughout. He also believes the convenience and intelligence of this approach is key to Zeus’ value proposition.

“Our systems integration is more efficient, and a safer method that will minimize liability and warranty issues,” he says. “This will make the Zeus Power Platform attractive to companies like Pegasus, because it drastically reduces the amount of time and labor it takes to put a bus body on a chassis and to make all the systems work correctly.”

Meredith Brandt is the communications manager for Zeus Electric Chassis.