NIST, NASA Launch Joint Effort to Develop New Climate Satellites
Audi A1 e-tron: Extended Range Electric Vehicle for City Driving

Voith Turbo Selects Maxwell Ultracapacitor Modules for DIWAhybrid System for Transit Buses

The DIWAhybrid system is based on Voith’s DIWA transmission. Click to enlarge.

Voith Turbo, a leading producer of heavy vehicle drive systems, has selected Maxwell’s 125-volt BOOSTCAP ultracapacitor modules (HTM125) for braking energy recuperation and torque assist in its DIWAhybrid parallel hybrid-electric transit bus drive systems. The DIWAhybrid system enables transit buses to improve fuel economy by as much as 35% compared with standard diesel buses, according to Voith.

Voith and Maxwell have entered into a strategic supply agreement through which Maxwell is Voith’s exclusive supplier of ultracapacitor modules assembled in the United States to meet local content requirements.

Voith inverter and energy storage system. Click to enlarge.

The HTM125 is encased in a rugged, splash-proof, IP 65-compliant, aluminum chassis, weighs less than 60 kg and measures 315x425x744mm. Integrated monitoring capabilities and a highly efficient cooling configuration enable it to sustain continuous current of up to 150 amps with minimal temperature increase in high-temperature environments.

Its modular design makes it a versatile building block to satisfy various application requirements, and up to 12 modules may be linked in series to deliver a total of as much as 1,500 volts. Maxwell also offers a complete line of standard 15- to 75-volt multi-cell modules.

Voith has booked various hybrid system orders for the California based transit bus manufacturer, Gillig LLC. Gillig has also completed system tests at the Altoona Bus Research and Testing Facility, a test center for new model buses and technology and I’m very pleased with the overall durability and performance the system has shown.

—Robert Wiss, Voith Turbo’s VP Road Division for the US market

DIWAhybrid. The DIWAhybrid is based on Voith’s DIWA heavy-duty transmission, which has more than 100,000 units installed worldwide. The parallel system operates on a power split principle.

The asynchronous motor/generator in the system delivers constant power of 85 kW, with maximum power of 150 kW. During braking, the motor works as a generator and optimally complements the DIWA secondary retarder.

Voith also offers the ElvoDrive—a serial hybrid concept developed for buses with lower average speed.

Voith Turbo, a provider of hydrodynamic drive, coupling and braking systems for road, rail and industrial applications, as well as for ship propulsion systems, is a Group Division of Voith AG. Established on January 1, 1867, Voith is now one of the largest family-owned businesses in Europe, with 39,000 employees, US$7 billion in sales, and more than 280 locations worldwide.




If a rather small box of super caps can lower fuel consumption by 35% on a large class 7 or 8 truck, it should do much better on a pick-up, SUV, large cars etc.

Cost wise, it could be about the same as a 20 to 24 Kwh battery and it would certainly last much longer.

As it been tried?


On a transit bus a box of super caps can lower fuel consumption by 35% because of the necessary stop-and-go nature of its driving cycle. In a private vehicle the goal is to do a more-go-and-less-stop driving cycle.

Certainly, where that's not possible, any hybrid system will lower fuel consumption and a system that can cycle brake energy in&out with less losses more quickly (like a flywheel or super cap) will save more fuel.


Caps in transit buses make sense to me. The battery life and performance on take off would be the issues. Regenerative braking should be good. Perhaps this is Maxwell's niche market.


City buses &taxis & garbage trucks could be good candidates?


Trash trucks have lots of power hungry hydraulics that is not easily replaced by motors although you could power the hydraulics with a motor. The range might not be good, but they might be quiet which would be worth the effort.


All city vehicles should have some kind of energy recuperation, be it hydraulic, kinetic, electric or even just stop/start.

I suppose some of the manufacturers are small and do not have the engineering bandwidth to implement it rapidly.

As the techniques become well known, and packaged solutions become available, we should see it coming up

When the standard Ford Transit has energy recovery, we will have made some progress.

As well as lowering fuel usage and CO2, it will also lower noise and "local" pollution such as NOx which would be very good for city dwellers.

It seems like a no brainer to me.

The comments to this entry are closed.