With enthusiasm for electric school buses rapidly growing, more operators may be interested in fleet electrification, but be curious or concerned about what that entails for maintenance.
Although there are some differences, many maintenance elements remain the same, as sales representatives from The Lion Electric Co. demonstrated on Saturday at the California Association of School Transportation Officials’ (CASTOs’) annual conference, which was conducted virtually this year.
John Vaughn, sales manager; Peter Tuckerman, director of sales; and Edwardo Gonzalez Caamaño, sales manager, conducted a virtual walk-through of a LionC bus and detailed the similarities and differences between electric school buses and those powered by diesel, gasoline, propane, etc.
Drivers may be hesitant to try these relatively new buses, but many components, such as steering and the throttle, should feel very familiar, Caamaño said.
From the entrance to the rear doors, the bus is essentially the same with a key ignition, switches, and a dashboard. Under the hood, electric buses still include components such as coolant and hoses.
They also perform similarly to buses with a diesel engine, with a capability of 335 horsepower and 1,800 ft-lb. of torque.
Additionally, in tandem with the high-voltage battery back used for propulsion, the electric bus uses 12-volt batteries to power auxiliary systems just like a conventional bus. If the bus’s batteries die, for example after a long period of storage without a trickle charger, they still need a jump-start, same as with a diesel bus.
One crucial difference to be aware of in maintaining an electric bus, is, obviously, the batteries. They also have several converters and inverters, including high-voltage cables, that transmit electricity from the batteries, starting at 60 volts, Vaughn said.
Most importantly, when performing maintenance, the technician must disable the batteries because they still have energy stored.
If, for example, a mechanic is drilling hole in a bus’s floor, they need to disengage the contactors in the batteries in every battery pack (the LionC has four) and wait 15 minutes before performing maintenance.
As added safety precautions, electric buses include a high-voltage battery disconnect system located inside the bus beside the driver’s seat, as well as a red button to press to stop the flow of coolant in the event of a coolant leak, Tuckerman said.
Other maintenance tasks are reduced in an electric school bus: there are fewer fluids to maintain, including windshield wipers and those to regulate the temperature of the bus’s interior. There are about 20 parts in an electric motor versus 2,000 in a diesel engine, which will create maintenance efficiencies in the long term as well, Vaughn said.
“Eight to 10 years down the road, you won’t need to take the bus to a third-party mechanic,” he added.
Another difference under the hood: electric buses have a noise generator since the buses run so quietly, to alert students and other drivers of their presence.
Behind the driver’s seat is a screen that mimics a dashboard and features diagnostics such as battery range, miles per hour, the state of battery charge in each pack, troubleshooting fault codes, and the heater temperature. This feature also collects more data on driver performance, which operators can use to improve mileage.
Without a transmission, there is no hill hold feature. The driver steps on the brake, releases it, and has three to five seconds to transition to the accelerator pedal to avoid rollback. (The bus is programed to creep forward if the driver eases off the brake.)
With electric buses, there is four to six times more brake and tire efficiency, depending on driving habits and maintenance practices. (Lion offers air brakes but recommends hydraulic braking due to greater efficiency.)
Caamaño recommends hypermiling — using driving techniques similar to those used to reduce fuel consumption — to improve speed and efficiency, noting that electric school buses can get up to and beyond one kilowatt-hour per mile. It comes down to the driver avoiding hard braking to take advantage of regenerative braking, he said.
“Let off the throttle so the vehicle slows down a bit,” Caamaño added. “That generates power from batteries and can add an extra 20 miles to the range. “
In addition, it is important to ensure the wheel bearing isn’t adjusted too tightly, so the bus can coast easily, Vaughn says, and check the alignment so the brakes aren’t dragging, which affects battery power consumption.
Operators can program when to charge the bus, for example, from 11 p.m. to 6 a.m., when energy costs are lowest, for maximum efficiency.