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Proterra selects Toshiba SCiB cells for next-gen electric bus

Proterra Inc. has selected Toshiba as the battery supplier for its next-generation, all-electric bus from Proterra Inc. The new fleet will use Toshiba’s Rechargeable Batteries (SCiB), a safe rechargeable battery solution with high-rate performance and long-life capabilities that is used in a wide range of applications, from EVs to grid energy storage. (Earlier post.)

Featuring a Lithium Titanate Oxide (LTO), Toshiba’s SCiB batteries have excellent thermal performance, enabling their high-rate charging capability. The lithium-titanate chemistry contained in SCiB makes the batteries highly resistant to thermal runaway and lithium metal plating, providing exceptional battery safety characteristics.

The 20Ah prismatic SCiB cell has a nominal voltage of 2.3 V, with gravimetric energy density of 90 Wh/kg and volumetric density of 177 Wh/L. The cell can charge from 0% SOC to 80% in 6 minutes. SCiB cells also offer high continuous power output.

SCiB products also offer minimal capacity degradation and are capable of 10,000 or more charge-discharge cycles, depending on operating conditions. 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.

With a rapid recharge capability and outstanding life performance, Toshiba’s SCiB battery is ideally suited for zero-emission public transit.

—Greg Mack, Vice President of Toshiba International Corporation’s (TIC) Power Electronics Division

In addition to having nearly six times the fuel economy per kilometer/mile (when translated into conventional fuels) of a diesel bus, Proterra electric buses feature a fast charge system that takes less than 10 minutes to charge during regularly scheduled route stops, making the buses well-suited to transit applications.


Juan Carlos Zuleta

This is great news for lithium producers since it's well known that this type of Li-ion batteries use much more lithium per kWh than other Li-ion batteries because it requires lithium not only for the cathode and the electrolyte but also for the anode.


Proterra may have to use aluminum buses to offset the relative Heavy weight of these batteries.

However, their extra ruggedness, very quick charge capabilities and longevity (10,000+ charge-discharge cycles) will certainly help to make these e-buses a success.

Batteries will continue to evolve and improved units will certainly be available by 2020 or so.


I expect Davemart to be gloating niw, big time as he's one of the early proponents of the Toshiba batteries.


I found the specs exciting, but progress has been slow, as it has in battery energy density in general.

What really got me though is that the Honda Fit which uses them has a very large reduction in range in cold weather.
The specs were supposed to mean that it had good performance down to -30c.

The energy density doesn't seem to have improved either.

Very disappointing from Toshiba.

Proterra is getting hammered by BYD for volume too.

Juan Carlos Zuleta

Or perhaps these buses may have to use something even better than aluminum: magnesium?


Altair Nano used to make the batteries for those buses, I wonder what happened?


Aluminum-magnesium alloys and various light weight re-enforced carbon-plastics could certainly reduce the total bus weight by 4 to 6 tons.

Our city used locally built aluminum buses between 1936 and 1958 before it switched to GM heavier steel buses. A lot of politics were involved. The six (6) local large aluminum factories can certainly supply all the aluminum required. Political decisions do not always make common sense.


Aluminium, let alone magnesium, would cost far too much for vehicles which are for everyday, cheap transport, not luxury Audi sedans.

BYD just builds buses by the thousand and sticks in loads of cheap LiFePo batteries for good range.


Juan Carlos Zuleta


As far as I know, BYD has not been allowed to commercialize its buses in the US as yet. So Proterra may have monopoly there for the time being. Only problem is that their buses cost twice as much as BYD's ones.


There have been some hiccups, but BYD buses have now passed US safety tests:

'The 40-foot version of BYD’s electric bus passed the Altoona Bus Research and Testing Center’s structural integrity program, which has the backing of the Federal Transit Authority. Altoona found the bus meets Federal safety standards, meaning it can legally operate on U.S. roadways. There had been some concerns regarding the quality of the BYD’s buses after pre-production models developed cracks from subpar welding.'


I thought I had read somewhere that Proterra was using a composite monocoque body already. Their website suggests its balsa wood and fibreglass, at least in part.

The were using Altair Nano lithium-titanate, maybe they are just sticking with what they know?


Recent steel 40-ft ICE city buses weight between 36 and 40 tons. It is possible to trim 4 to 6 tons off by using aluminum, aluminum alloys and composites.

The weight saved by removing the heavy diesel ICE and associated support components + fuel and by using lighter materials for the body is more than enough to offset the weight of very large low performance batteries such as those from Toshiba.

City buses are ideal vehicles to be electrified because they can carry loads of batteries without affecting their performances and can be easily recharge at each end of their routes if required.

BYD, Proterra, Volvo, Man and many others will mass produce city e-buses by 2018. Polluting diesel city buses will be mostly phased out by 2030.

Juan Carlos Zuleta


If your information is correct, I would envisage the advent of wireless "super duper charging" for all-electric buses fairly soon", just like I suggested for cars in an EV World blog some time ago (See: http://evworld.com/blogs.cfm?blogID=1156).


Wireless charging could eventually take a high percentage of the private and public chargers market. People will be willing to pay a bit more for the added convenience.

I can see two basic requirements for city e-buses:

1. invisible wireless charging facilities at selected e-bus stops and e-taxis stands

2. wired, variable high capacity charging facilities for longer stops at bus route ends.

City buses will be electrified by specific routes over 12 to 15 years.


"Proterra introduced its all-new, fast-charge, 100% electric bus in 2014. The all-new, 40-foot bus expanded on the EcoRide’s industry-leading design and engineering and delivered a longer, lighter and more fuel-efficient bus.
The second-generation bus measures 40-feet and weighs approximately 27,500 lbs., which is less than any other 40-foot transit bus on the market today."



At 27,500 lbs, 4 to 6 tons of batteries could be used, or enough for a full shift or double shift without recharge?


The 27,500 pound figure for the 40 foot bus that can transport 60 people includes the battery weight. Think of four people per 5000 pound SUV, here you can seat 40 people which would be 10 SUVs totaling 50,000 pounds, 27,500 pounds seems light to me.


If batteries are included in the 27,500 lbs total weight, Proterra must have used ultra light composite materials and ultra light batteries?

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