UQM for the Motors and Controllers, Eaton for Two-Speed Transmission
As 100% Battery Electric 40-Foot Proterra ‘V2’ Bus Replaces Its 35 Footers
Proterra has selected Toshiba to supply SCiB brand lithium titanium battery modules for its new line of fully electric 40-foot transit buses, which are to replace the Greenville, S.C.-based firm’s 35-footers. The second-generation “V2” buses have motors and controllers from UQM Technologies, and a two-speed transmission developed with Eaton.
Eaton also furnishes the high-power DC chargers used for in-route charging of the Proterra buses. The strategy allows a full-size transit bus with to perform a full work day without interruption.
The Toshiba batteries, designed to accept repeated fast charges, help make the Proterra in-route charging strategy possible.
“Toshiba’s SCiB batteries have excellent thermal performance, enabling their high-rate charging capability,” the manufacturer says. “The lithium-titanate chemistry contained in SCiB makes the batteries highly resistant to thermal runaway and lithium metal plating, providing exceptional battery safety characteristics.”
“With a rapid recharge capability and outstanding life performance, Toshiba’s SCiB battery is ideally suited for zero-emission public transit,” Toshiba International power electronics VP Greg Mack said in a release.
Toshiba’s SCiB products “offer minimal capacity degradation and are capable of 10,000 or more charge-discharge cycles,” the company says. “This operational life often exceeds that of the applications in which they are used, eliminating the need for battery replacement and reducing the environmental impact of waste batteries.”
100 Kilowatt-Hours Per Bus
“We see the SCiB battery as key to expanding environmentally-friendly modes of transportation with optimum power performance in North America,” Mack said.
Proterra has configured the 40-foot V2 with eight active liquid-cooled Toshiba SCiB modules affording 100 kilowatt-hours of energy storage. The Toshiba units, with BMS/battery management system designed and programmed by Proterra, is located is the bus undercarriage, improving center-of-gravity and vehicle handling and easing access for maintenance.
“We are very deliberate in each part we select for our buses, putting vendors through a rigorous qualification process,” Proterra CEO Ryan Popple says in the Toshiba announcement. “Battery quality is critical to the performance of electric vehicles,” he said. “SCiB technology will enable Proterra to offer its customers the highest-performance, safest, and most reliable urban transit vehicles.”
50 Mile Nominal, 30 For Sure
Single-charge range is a “nominal” 50 miles, but Proterra prefers to state it at a conservative 30, Popple told F&F – a figure operators can count on even if hauling a full load of 70 passengers, running air conditioning or heating, at the highway speeds necessitated for some suburban routes.
With the two-speed Eaton gearbox, he says, “You get a tremendous amount of low-end torque for city driving [and hills], and shift to highway speeds with high efficiency for suburban drive cycles.”
Two of Proterra new 40-footers have been ordered by Proterra’s largest customer, Foothill Transit in Southern California, and two with options for 200 have been ordered by King Country Metro in Seattle (F&F, September 9. The V2 bus is 1,000 pounds lighter than the firm’s 35-footer, approximately 60 of which are either in-service or on-order, Popple says.
A Few More 35s
“Transit,” he says, “can have a zero-emission future.”
The 40-foot Proterra V2 is priced at $825,000. Deliveries are to start this year or early next. Production of the existing 35-footer – Popple calls it the V1.5 – is now expected to extend into early 2015, he says, behind follow-on orders from existing operators.
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Source: Toshiba with Fleets & Fuels follow-up