Proterra Catalyst E2: All-Electric Bus With 560 Km Range

Haven’t heard of Proterra before? The California-based automotive start-up is on the run to eliminate fossil-fuel based transit buses with zero-emission electric vehicles without compromising on vehicular performance or uptime. The company has recently unveiled new range of electric city buses – Catalyst E2 – that promise a nominal pure-electric driving range up to 560 kms (350 miles) per full charge or equivalent 18 hours of break-free operation typically required for toughest bus routes in US.

electric bus proterra battery technology

One of the world’s most energy-efficient transit buses ever made, the Catalyst E2 series are run by Lithium–titanate battery pack of 440 – 660 kWh housed under the floor board, and requires around 3.5-5 hours to replenish from nil charge, via either in-depot plug-in chargers or on-route overhead fast chargers developed by the company. The bus with 77 passenger capacity can hit a top speed of 104 kmph (65 mph), with 0-30 kmph in 6.8 seconds – a biggest accomplishment for an EV of this size. Further, such nimble drivability is very important for start-stop-start nature of urban transit systems, thereby reducing the operating time and energy consumption.

The zero-emission electric bus is built on tailor-made EV chassis from lightweight and durable carbon fiber composite. Together with other weight-saving efforts, the bus weighs a mere 17.6 tonnes in spite of a heavy battery pack. It is powered by a 220 kW peak permanent magnet drive motor with a roof mounted cooling system. The power is delivered to the wheels via 2-speed auto-shift EV gearbox designed by Proterra. There is also an integrated battery management system to monitor the whole electric propulsion system. Featuring air disk brakes in all wheels, the Catalyst E2 is equipped with standard ABS with optional traction control. The bus rides on a multi-link air suspension.

Also Read: BYD Electric Double-Decker Bus On London Streets – All You Need To Know

The Catalyst E2, rightly named as Efficient Energy (E2), appears to offer a no-compromise alternative to diesel/ CNG buses, as the claimed nominal driving range of 400 to 560 kms is adequate to meet the daily mileage needs of our city transit buses. Yet, driving range is a tricky things as it is influenced by a number of factors including driving style, constant braking, topography, temperature, traffic, etc. In a recent closed-track testing, the Catalyst E2 has achieved an unbelievable mileage of 965 kms (600 miles) on full charge. However, test conditions are far different from real-life scenarios, and that’s why Proterra is sure of a modest 560 kms range that even electric cars like Tesla can’t win over for now. The latest 2017 Chevy Bolt EV achieves a top-class range of mere 383 kms on full charge, that too for a tiny car! What Proterra promises for a giant EV is simply a ‘revolution’, and may lead to widespread market adoption of all-electric transit buses in the years to come.

Proterra offers the Catalyst E2 in 10.6 metre and 12 metre specs, along with 6-year battery warranty. The company also manufactures EcoRide BE35 range of electric buses along with the Catalyst. With its assembly situated in California and South Carolina, the Proterra is active only in the North American region with more than 312 pure-electric transit buses sold to 35 different operators in the region.

Also Read: Tata Ultra Electric Mini-Bus from 2016 Auto Expo

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Dhiyanesh Ravichandran

Editorial consultant (Automotive and Technology), academic, and blogger based in India. He can be reached at

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