Alternative Drive Systems – Generation B
High involvement
“There are lots of teams involved,” explains Strategic Project Manager Anton Sonntag, who heads the B-Class F-Cell project from Sindelfingen and is himself a member of the Development department headed by Klaus Badenhausen. “Apart from Research and Development, all the relevant departments for product development have been in on the project from the very beginning,” he continues. “That includes sales, purchasing, quality management, and even aftersales and customer care.”
Keeping a low profile
The first test prototypes are already out and about on Europe’s roads. The only thing that distinguishes these vehicles from gasoline or diesel models is the unobtrusive “F-Cell” badge stuck on the rear. Not that the vehicles have anything to be ashamed of. On the performance front, for example, the electric motor delivers a peak power of 100 kW and maximum torque of 320 Nm, which translates into a top speed of 174 kilometers per hour. Likewise, doubling the pressure in the hydrogen tank from 350 to 700 bars has boosted the vehicle’s range to a very acceptable 400 kilometers. What’s more, the zero-emissions drive system consumes no more than the equivalent of 2.9 liters of diesel per 100 kilometers.
“Lab tests have already told us that the components function very reliably both on their own and together.”
Jürgen Friedrich, Daimler Research and Development
 
 
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Exacting tests under lab conditions:
In Nabern, the new F-Cell vehicles
undergo numerous trials
on a rolling-road fitted with special
measuring equipment.
In his office in Nabern, Jürgen Friedrich lifts his eyes from a stack of data and nods in satisfaction: “That all looks pretty good. Lab tests have already told us that the components function very reliably both on their own and together, and now that’s been confirmed in practice.” Friedrich is in charge of Operation and Service for the entire F-Cell test fleet, which now comprises over 100 test vehicles, prototypes, buses, and small-lot production cars. He is familiar with the kind of surprises that this technology has been capable of delivering, ever since NECAR 1, the first fuel cell research vehicle with the Mercedes star, first hit the road back in 1994. In the meantime, however, researchers and developers at Daimler have got a pretty good handle on this technology. That’s evident, for example, in the success of customer tests with the 60-vehicle test fleet of the predecessor A-Class F-Cell, which has been running since 2005 in California, Michigan, Tokyo, Singapore, Frankfurt, Stuttgart, Berlin and, most recently of all, Iceland, notching up a total of 1.7 million kilometers in the process. In particular, the fuel cell stacks have proved to be substantially more reliable in daily operation than was initially predicted. “One vehicle has completed 150,000 kilometers and 3,000 operating hours on just one stack, and virtually without any problems at all,” says Friedrich.
Just like Formula One
That said, the specialists from Field Service, who look after all the fuel cell vehicles during testing, are an integral part of the project. They’re responsible for putting together the practical know-how that will be handed on to selected Mercedes-Benz workshops and service points in the run-up to the market launch. That’s why each vehicle is equipped with a “black box” that sends all the data to Nabern via WLAN and the Internet. This is then rapidly analyzed by experts at Field Service. “It’s a bit like the technology used in Formula One racing,” says Friedrich. “Only we don’t get to be on prime time TV every other Sunday.”
One of the principal objectives of the winter tests in Sweden is to examine the stack’s resistance to cold. A classic problem with previous fuel cell systems was that the water produced during operation of the PEM fuel cell remained in the stack once the system had been switched off and then froze at sufficiently low temperatures, causing problems when restarting. “Water under the bridge!” says Thomas Poschmann with a grin. Poschmann, a project manager in Nabern, heads the project to develop the entire powertrain, including the hydrogen tank, fuel cell, battery, and electric motor. “The B-Class F-Cell uses the new generation of fuel cell systems, which has been developed in Nabern by NuCellSys, a joint venture between Daimler and Ford.” The stacks, meanwhile, are developed by Automotive Fuel Cell Cooperation (AFCC), the Vancouver-based successor of the automotive division of Ballard Power Systems. Daimler holds a majority stake of 50.1 percent in AFCC, which was founded in February of this year, and therefore has industrial control. Ford has 30 percent of the shares and Ballard holds the remaining 19.9 percent.
“Our colleagues at the Ulm Research Center first tested out the new technology in the F600 research car,” Poschmann explains. “This includes innovative gas-gas humidification of the cells with hollow-fiber modules, which gives us a cold-start capability of -15 degrees Celsius and lower. There’s no problem with freezing temperatures once the fuel cell system is running, since the stacks heat up to 80 degrees.”
In fact, the new vehicles have impressed the researchers not just with their cold-weather behavior but across the full range of tests in Sweden, as project manager Sonntag confirms: “Everyone involved in this development project is thrilled with the driving performance of the cars and the robustness of the technology. With the B-Class F-Cell, we’ve taken another major step toward the series production of a fuel cell car.” 
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