BYD electric bus provides 30-h service on single charge

  • 30-Jan-2014 01:49 EST
BYD All-Electric Bus.jpg

The BYD electric bus tested at MTA offered an average range of 140 to 155 mi (225 to 250 km) between charges. Charging takes 3 to 4 h to return to full capacity and was done at night during off-peak hours.

BYD Motors and the New York Metropolitan Transportation Authority (MTA) recently announced some findings from a two-month pilot test on a 40-ft (12-m) BYD battery-electric bus conducted in Manhattan from Aug. 25 to Oct 25, 2013.

“The general purpose of the program was to evaluate how an electric bus could perform in New York City’s heavy traffic, whether the electric bus can meet the twin challenges of operating in the stop-and-go traffic of Manhattan while maintaining high levels of passenger comfort and operational performance,” MTA spokesman Kevin Ortiz said in a statement.

The bus tested at MTA offers an average range of 140 to 155 mi (225 to 250 km) between charges. Charging is intended to be completed only at night during off-peak hours to reduce demand on the grid, and takes 3 to 4 h to return to full capacity, according to the bus maker.

Testing was conducted on various routes throughout Manhattan, including M20, M42, M104, M98, M60, and Bx27. The total distance covered during the trial was 1481 mi (2383 km). BYD claims that its all-electric bus had an average battery consumption of 1.4 mi (2.25 km) per % SOC (state of charge), translating to more than 140 mi (225 km) per full charge in heavy traffic. The average speed of the electric bus was about 4 mph (6 km/h).

After two months, the electric bus’s average battery duration was 0.3 h per % SOC, or 30 h of operation per full charge. An advantage of electric buses, compared to diesel bus technology, is that they do not idle when in heavy or stopped traffic, thus conserving “fuel” and reducing greenhouse gas emissions.

Another advantage is that because BYD buses do not have an internal-combustion engine or transmission, along with other conventional components, maintenance costs (and labor) can be reduced “significantly,” according to the company. Regenerative braking also reduces normal brake-pad wear and maintenance.

BYD and MTA claim that the expected operating-cost-per-mile of an electric bus is about $0.20 to $0.30, compared to $1.30 per mile for an equivalent diesel- or natural-gas-powered bus in New York.

BYD also recently completed the first phase of a 10-month trial, which commenced this past summer in Gatineau, Quebec, and Ottawa, Ontario, again using a 40-ft BYD-supplied electric bus. The evaluation was performed by the Société de transport de l'Outaouais (STO) in conjunction with AVT (the Société de gestion et d'acquisition de véhicules de transport). Salah Barj, Director of Planning and Development at STO, presented partial findings at a recent conference in Canada.

“The BYD electric bus...was able to run our required 8-hour shift in service with only a night-time single charge at our bus garage,” said Barj. “BYD’s bus itself has onboard chargers so that only 60 kW of grid ac power was delivered at night to the bus through a power interface. This made for very convenient charging of the electric bus so that no peak-rate power was consumed.”

STO found that the average speed of drivers on Gatineau and Ottawa routes was about 23 km/h (14 mph), and the resulting distance the bus could travel at this average speed was 250 km (155 mi)—the equivalent of 1.3 kW·h/km without air-conditioning on and 1.5 kW·h/km with A/C, and full passenger loads.

The range achieved in both the MTA pilot and the Canadian trials is attributable to the sizing of BYD’s iron-phosphate battery. The company claims to provide the largest battery available, with a 324-kW·h total energy storage capacity. BYD also claims that when average speeds increased to the maximum speed of 70 km/h (44 mph), the overall bus efficiencies increased to 0.75 kW·h/km (1.2 kW·h/mi) traveled, and the difference between “with” and “without air conditioning” is lessened.

All of the EV componentry used in the electric-bus trials is production-ready, according to Micheal Austin, Vice President of BYD America. He noted that more than 1000 12-m electric buses “of this approximate design” had been manufactured by the end of 2013.

One particular challenge was presented by the colder temperatures during the trials in Canada, Austin shared.

“Cold-weather heating was very challenging. The bus ran fine, but supplemental [diesel] heating systems are required in Canada for passenger comfort—and maybe [in] New York this week,” he said half-jokingly, referring to the “polar vortex” that brought frigid temperatures to the Central and Eastern U.S. in late January.

BYD continues its electric-bus evaluations in partnership with the Société de transport de Montreal (STM) until spring 2014.

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