FUEL CELLS

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As new fuel cell service and repair ... comprises groups of individual cells for series voltage output, has no moving parts. .... current Mazda Millenia model, so.
SERVICING VEHICLES BY STEVE FORD THE CAR GUY ®

The prospect of working on hydrogen-powered fuel cell vehicles has many technicians shaking in their boots. Truth is, servicing these cars won’t be all that much different or dangerous than what you’re accustomed to right now!

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fter more than a century of dominance by the gasoline-powered internal combustion engine (ICE), the idea of electric vehicles taking over our highways is admittedly distant. After all, the car didn’t simply replace the horse the instant the calendar changed from 1899 to 1900.

Photo courtesy American Honda Motor Co.

Still, there’s wide agreement that electric “propulsion,” as automotive futurists like to call tomorrow’s drive systems, will unseat ICE powerplants as the champion during the coming decades. The toughest critics of EVs point to the fact that most of them still generate pollution from burning coal or natural gas at remote locations to supply the

electricity they consume. Yet, according to statistics cited by author Jim Motavalli in his recent book, Forward Drive: The Race to Build “Clean” Cars for the Future, “...it would [still] take 13 EVs getting their energy from a fossil-fuel-burning [power station] grid to equal the volatile organic production of the average gas car, six [EVs] to equal its nitrogen oxide production, and 1440

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SERVICING FUEL CELL VEHICLES to match its carbon monoxide.” Yet, with such obvious advantages, EVs have been challenged most by the limited range of conventional batteries. “If the auto industry witnessed a breakthrough in battery technology— the idea of getting more than even half the “per-tank” range of gasoline-powered vehicles—few would dispute the idea that EVs would be expanding rapidly into our national fleet today,” said Zale Coffman, analyst with the Santa Barbara Electric Transportation Institute, in California. But what about the possibility of refilling a “tank” with electrons instead of recharging a battery with electrons?

Alternative ‘Energy’ for Alternative ‘Power’

the use of fuel cells that strip electrons out of hydrogen. Where conventional storage batteries rely on an external electrical charge to “fill up,” fuel cells supplant the battery and generate continuous electricity so long as

Power Without Moving Parts Even in the early prototype stages, fuel cells have demonstrated notable reliability. When the Chicago Transit Authority ran trial fuel cell-powered

Illustration courtesy DaimlerChrysler

As the alternative-power saga unfolds, a means to leapfrog the limited range of EVs appears to be arriving through

From a service perspective, the challenge is keeping the external fuel cell support system operating correctly to ensure balanced processing of the hydrogen and oxygen.

they receive an uninterrupted flow of hydrogen and oxygen. Of course, from a service perspective, herein lies the challenge: keeping the external fuel cell support system operating correctly to ensure balanced processing of the hydrogen and oxygen. As new fuel cell service and repair scenarios approach, perhaps this balance aspect offers our first fundamental comparison to ICE systems. Where we have concentrated on precise ignition to harness power from mixing gasoline and air, fuel cells parallel this emphasis, but with balanced metering of independent hydrogen and air instead.

The fuel cell stack, which comprises groups of individual cells for series voltage output, has no moving parts. With only an electrochemical process occurring, the fuel cell stack relies on external support devices for efficient operation.

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Yikes! Hydrogen? According to Scott Staley, chief engineer for Th!nk Technologies at Ford Motor Company, answering the hydrogen safety question is a principal educational goal in technician service training for fuel cell vehicles. “If gasoline were introduced as an all-new fuel to the EPA and Dept. of Transportation today, it would likely be scrutinized as much or more than hydrogen,” said Staley. “Consider the fact that gasoline is highly flammable as a vapor or liquid, poisonous to touch and toxic to the environment. Hydrogen does pose dangers, but just like gasoline, it requires that techni-

Photo courtesy American Honda Motor Co.

buses in extended performance evaluations, only ten of the 4500 fuel cells incorporated in the testing were reported to have malfunctioned. Moreover, even those ten cell malfunctions may have been preventable from a service standpoint. With no internal moving parts, fuel cells are individual catalyst plates, each of which produces approximately .7 volt. The voltage produced by each cell occurs when electrons are extracted from passing hydrogen in an electrochemical reaction with oxygen. Individual cells must then be connected together by the hundreds into what are called “fuel cell stacks” to produce the typical 320 to 450 volts required for EV drive motors. Again, similar to the dynamics of fuel and air in an ICE system, in the same manner that a lean air/fuel mixture can cause overheating and damage in a combustion chamber, an improper hydrogen/air mixture can cause a fuel cell to overheat. Conversely, too much hydrogen (a “rich” mixture) can literally “flood” the fuel cell with water from the humidity inherent in the hydrogen. Of course, just as there are parallels between ICE and fuel cell systems, there are important differences. One of the greatest areas of apprehension about fuel cells arriving in service bays is understanding hydrogen. Hydrogen took us to the moon, but can it take us to the corner market...safely?

Honda has been a major player in fuel cell vehicle technology. This FCX prototype was developed with both direct (hydrogen-fueled) and indirect (methanol-fueled) delivery methods in mind. The company says it will have a full-fledged production model ready for the masses by 2003.

cians learn and follow a specific set of safety guidelines. And when you consider the dangers of gasoline, technicians are already following fairly rigid safety standards,” he added. Here are a few quick facts to get you up to speed in the race to “fuel up” with this new energy source:

One area of apprehension about fuel cells arriving in your service bays is understanding hydrogen. It took us to the moon, but can it take us to the market...safely? •Hydrogen is the lightest and most abundant atom in the universe. •Hydrogen atoms are very small. With no neutron and only a proton and an electron, hydrogen atoms can slip through spaces and materials that

would otherwise restrict other fuel atoms. •Hydrogen can be carried on board vehicles in liquid or compressed gas form, although the compressed gas form is most likely in the near term. Sam Romano, principal investigator for fuel cell programs at Georgetown University, points out that perceptions about hydrogen fuel being easily explosive as an escaped gas tend to be exaggerated, too. “That’s another area of need for education in the service community,” said Romano. “There’s not as much potential for loose hydrogen to explode as some might think. First of all, because it’s so light, it wants to rise up quickly into the atmosphere. Second, since it wants to go up, it doesn’t ‘pool’ easily—which it needs to do in order to concentrate. And it needs to be concentrated to explode.” “Technicians should first be equipped with these background concepts about fuel cells and the nature of hydrogen to better appreciate fuel cell external support systems,” said Ford’s Staley. Which brings us to the devices that lead into and out of the fuel cell stack.

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SERVICING FUEL CELL VEHICLES Fuel Cells ‘On the Hook’ Now, when you consider the fact that hydrogen atoms are light, small and can be stored on board a vehicle, how does that shake out in service? Zale Coffman explained that techs should understand the two main forms of hydrogen delivery. “The technician will deal with either a methanol, or ‘indirect,’ delivery of hydrogen, or a ‘direct’ delivery,” he said. “The advantage of methanol is that it’s a liquid fuel that can be distributed through modified fuel stations— in contrast to hydrogen, which requires a whole new distribution infrastructure. The direct form of hydrogen delivery on board the vehicle tends to be simpler and more reliable, as the hydrogen can be stored on board and then pumped directly into the fuel cell,” added Coffman. According to Coffman, since the fuel cell can process only pure hydrogen, use of methanol requires processing through a device called a reformer, which strips the hydrogen out of the methanol. “The reformer adds a degree of complexity and new service requirements above ‘direct’ hydrogen,” said Coffman. “Simply stated, the reformer uses heat and water from a steam process to extract hydrogen from the hydrocarbon molecules in the methanol.” Coffman also noted that when running either the indirect (methanol) or direct (hydrogen) form of external support systems, a fuel cell vehicle will most likely break down due to a malfunction in a more conventional device outside of the fuel cell rather than the fuel cell itself. Staley agrees, saying that “fuel cell failures are typically caused by malfunctions in auxiliary devices, such as pumps, regulators or cooling systems.”

Similar Skills, But More Electronics Another important area in expanding technician knowledge about fuel cell architecture is the aspect of increased on-board electronic controls. According to Georgetown University’s Romano, the differences between repairing today’s automobiles and ser-

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vicing 21st century fuel cell vehicles are evolutionary, not revolutionary. “When you consider today’s automobiles, you find that you’ve got a growing number of microprocessor systems—heating and air conditioning, engine controls, body electrical and new telematics,” said Romano. “With the introduction of fuel cells into cars, you’ll see similar auto technician skill requirements with increased emphasis on dealing with electronics. For example, optimum fuel cell operation requires integration of four electronic control systems—fuel cell stack controls, fuel cell reformer controls, propulsion or ‘drive system’ controls and, finally, an interfacing of these systems with total vehicle electronics.” Romano explained that fuel cell

When a fuel cell vehicle breaks down, it will most likely be due to a malfunction in a more conventional device outside the fuel cell rather than the fuel cell itself. system controls will incorporate new embedded microprocessor programs, and include their own fault codes and diagnostic strategies. “Technicians will have to know about processors, as they already do today,” he said. “They’ll have to know what systems to check and how to check them, but they’ll use many of the exact same tools and techniques they’re using today. “The fuel cell itself will be a ‘black box,’ meaning that if the technician isolates a fault to the internals of the cell, that technician will simply remove it as a modular component and ship it to the manufacturer for repair—much like other devices today, such as a microprocessor,” he noted.

Pumps, Sensors & Seals Amidst the added on-board microprocessor controls will be an array of new pumps, sensors, lines, junctions and high-pressure seals, says Ford’s Staley. “Since compressed hydrogen tanks store hydrogen at approximately 3600 psi,” he said, “technicians will need to prepare to deal with new high-pressure lines, regulators, filters, pressure sensors and safety-sensing devices. At the same time, many technicians are already familiar with similar devices on propane and natural-gas-powered vehicles. So again, fuel cells bring many familiar technologies. “Additionally,” added Staley, “when you look at the fuel cell car, you’ll find that the majority of components are used out of existing vehicle applications. For example, many of the components in the high-pressure fuel delivery system are similar to those used in production naturalgas vehicles. And the air compressor we use (to pump air into the fuel cell) is the supercharger from our current Mazda Millenia model, so technicians will deal with many familiar devices.” Staley continued: “So, you can see that there’s no need to retool the whole industry here for fuel cells. We’re going to use existing service infrastructures with today’s technicians retrained in fuel cell safety procedures and equipped with required new tools.” The days of the dwell meter and the timing light may be gone, and the advent of new technologies does bring new challenges. Still, what started as microprocessor control of electronic ignition has turned into EFI, ABS and dozens of other new acronyms. We’ve adapted before and we’ll adapt again. Fuel cells introduce another dimension, but not another universe. Visit www.motor.com to download a free copy of this article. Copies are also available by sending $3 for each copy to: Fulfillment Dept., MOTOR Magazine, 5600 Crooks Rd., Troy, MI 48098.