BYD’s Type D Electric School Bus Might School Traditional Buses

It's a wonder that all-electric school buses have taken this long to become a consideration. The constant stopping and going, the short range most school buses drive, and the long periods they sit for makes them the perfect choice for an electrified powertrain. That's what makes this Type D School Bus from BYD, which debuted in 2021, so compelling. And due to its choice of battery, it's less likely to catch fire than your average Tesla.

The Type D is a large bus capable of carrying up to 84 people plus the driver thanks to its 36.32 to 40.5 feet length options. Obviously, the shorter length will mean less people to carry. No matter how long the bus, the wheelbase remains 274 inches (22.83 feet). When you compare that to your typical rear-engine, forward-control school bus, the need for space for the engine, its transmission, and ancillary components at the rear means the rear wheels go further back the longer you make it because those parts need space to exist. That can be up to 5 feet or more of lost space and additional rear overhang, as well as the emergency rear exit being cumbersome to get out of because students would have to climb through a long but narrow window or panel. The other solution to gain rear space is to build a front-engine forward-control bus, but now you're taking space away from the driver due to needing a large dog house to house the engine and transmission. Even worse for some areas is that you'll need to use a smaller engine that's usually less powerful than what you could fit in a rear-engine bus.

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The in-wheel motor the rear axle uses on the BYD Type D allows it to gain much of that rear space back because the motor is no taller than the inner diameter of the wheels. The cooling components for those motors, the inverter, the motor controller and the batteries are then the only parts you need to find space for, and most of these components require no more than a couple of cubic feet of space. The heat exchanger would be the tallest part out of those listed, but it's also a thin part that's no different from your radiator in your car. A battery pack can easily fit under the floor and between the front and rear axles of the bus.

Going with a BEV also allows the Type D to have an easy-to-use and exit rear emergency door that is also lower to the ground (when compared to the typical rear-engine, forward-control school bus). This also reduces the height from the ground to the bottom of the emergency exit, which is around 40 inches on the Type D. That's roughly the same drop height as a front-engine school bus.

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You also get far more torque than you would using an ICE. At 201 hp and 406 lb-ft of torque at each rear side of the rear axle, the BYD Type D has a total output of 402 hp with 811.32 lb-ft of torque. This allows the 28,880-pound school bus to easily hit its top speed of 65 mph and tackle a grade of up to 20 percent. Also, due to being a forward-control bus, its turning radius is 34.3 feet for its 36.2-foot length, and 37.8 feet for its 40.5-foot version, which are rather impressive numbers for their lengths.

All versions ride on an air suspension system with mechanical leveling valves rather than leaf springs to ensure your children aren't bumped around too much after a long day of learning and carrying those very heavy book bags. They are also treated to relative silence when compared to a diesel-powered bus, so what they learned isn't removed by the external stress one feels during a loud bus ride. The electric motors and battery packs also reduce the service costs related to running an ICE-powered school bus. There is no oil to change regularly, no diesel to fill every day, no grease to apply to a driveshaft after many hours of service.

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Then we get to another advantage of building an all-electric bus: the lower floor height. Your typical school bus, forward-control or otherwise, is built on a C-channel or box frame as that has been the industry standard for decades. It also requires steep steps to enter and exit this type of bus, meaning those who have mobility disabilities can't easily enter or exit. The BYD Type D still has steps as the floor still sits above the tires, but not as high as a conventional school bus, so the steps aren't as steep, making the Type D safer to enter.

Another huge advantage of the BYD Type D versus other school buses, even other electrics, is that it's capable of bi-directional charging. When the bus is done driving for the day, it can hook up to the school's power system and help reduce the load on the grid while class is in session. Just before school ends, the buses can be charged to capacity and drive up to 155 miles on a single charge with its 255-kWh (230 kWh net) battery pack. When it is charging, the charging time ranges from 2.1 to 2.6 hours on its DC Fast Charge 110-kW rate or 11.9 to 12.4 hours on its 19.2-kW AC charge rate.

For those of you pointing out that we mentioned not filling with diesel every day, keep in mind that the BYD is less expensive to run per mile in terms of refueling costs even in states where electricity is particularly expensive. We also need to remember that EVs are capable of energy recuperation while coming to a stop, which reduces how much more charge you need to add once its day is done. That's something a school bus will do many times on its run, and is another factor in the Type D's reduced costs in service as the disc brake system would only need to be used sparingly to bring it to a stop.

The Type D also doesn't necessarily need a person to hook up a cable to charge. According to BYD, it can use a wireless inductive charger or the SAE J3105 overhead charging station. The J3105 is a standard where either the bus will raise a small crane to connect charging leads to the charging pod of the station or a charging station will lower a one with charging leads that make contact with the leads on the roof that connect to the battery. This way, while the bus is not in motion it can charge without the need for someone to physically connect a charger lead into the bus. Best of all, the process can be fully automated and require no human intervention to charge the bus, not even as much as a switch to engage the system by the driver.

While you might be concerned about lithium-ion batteries and fires with your children on board, as rare as they actually are, the BYD Type D is equipped with safer lithium-iron-phosphate (LFP) batteries that have a far lower risk of fire due to thermal runaway, puncture shorting, or even severe bending of the battery pack.

That's not the only safety advantage that the Type D has. For your kids, the Predictive Stop Arm monitors approaching traffic and tells students when it might be dangerous to cross the road. For the driver, there is an electronic stability control system, a collision avoidance system, and a 360-degree monitoring system to make sure the Type D won't potentially hit pedestrians and cyclists when operating at slow speeds. Finally, the BYD school bus is equipped with a four-corner disc brake system with ABS to make braking predictable, fast, and safe.

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This is why it's a wonder why it's taken so long for an all-electric school bus to become a viable alternative to its ICE counterpart. Fully electric and hybrid transit buses have been common for nearly a decade or longer, while school buses have mostly relied on carbon-based fuel technologies (including some CNG or propane options). With BYD using what it has learned from its own transit bus line, we're finally seeing a true alternative to the diesel-engine school bus with its Type D. Tie in lowered costs for servicing and maintenance, along with the advantages of bi-directional charging with the safety of an LFP battery pack, and the days of a clattering and rough riding diesel school bus are potentially behind us.