Lead for Hybrid 01
Lead-acid for Hybrid Vehicles
Can it make the grade?
by Shirley an Donald Georgi
Without making the case for hybrid vehicles, their expanding presence in both busses and automobiles suggests that some level of benefit and demand does exist for them. For purposes of simplicity, this presentation will only focus on the hybrid which does not have plug-in capability, obtaining all of its battery energy from a combination of IC engine charging and braking regeneration. It also does not seaparate the degree of battery assist. Hybrids achieve greater fuel economy by recovering braking energy and allowing the IC engine to operate in a more highly efficient domain to improve economy and reduce emissions.
Battery power in transportation has fallen into a perceived well of futility after the failure of pure electric auto power via California’s mandate. The vehicles did not offer the needed range, recharge convenience, cost or vehicle size because mandates could not produce the necessary technology.
At the Electric Transportation Industry Conference (ETIC) in Florida of December 2003, Dr. Pat Moseley (left) of the International Lead Zinc Organization and the ALABC, and Allan Cooper (right) of the European Advanced Lead Acid Battery Consortium discussed their work on the Foresight Vehicle, which is a Honda Insight being retrofitted with an advanced Lead-acid battery system. Allan Cooper presented the progress to date on this program. He will also be providing an update at the Battery Council International Meeting in May.
The European RHOLAB (Reliable, Highly Optimized Lead Acid Battery) project3 is in the U.K and is funded jointly by the European arm of the ALABC and the UK Government’s Foresight Vehicle Programme. It is focusing on removing the Nickel-metal hydride battery pack from the current Honda Insight and replacing it with the new RHOLAB system. In some respects this will make it a hybrid of the original Insight or a hybrid-hybrid. The battery system used is being supplied by Hawker Batteries having the CSIRO-Hawker patented technology. The system will be tested in order to gain a better understanding of the factors influencing the life and reliability of the battery in HEV applications. The research will also focus on the design and development of a high-performance battery management system (BMS) with the goal of increasing the VRLA cell life. The research also centers on the development of a new VRLA cell state-of-charge algorithm that can deal successfully with the complex hybrid applications. Because Lead-acid provides a cost savings in comparison with other chemistries, Allan Cooper and his colleagues feel it can be an excellent way to make the HEV an affordable choice.
Dr. Moseley stressed that creating a 36 Volt battery is not simply putting three 12-Volt batteries together but rather is an extensive technical project requiring new battery technology design and engineering, specifically tailored to the HEV. (Staff photo)
The rules have changed with the advent of the gasoline/battery hybrid vehicle. With the IC engine operating over a more efficient range and providing on-the-road recharging to the batteries, the battery pack no longer has to be of such enormous size that it eats up the back seat and trunk. Hybrid builders see the total battery pack cost go down because gasoline is the energy source allowing less cells to be used. This opens doors for higher cost high-tech batteries such as Nickel-metal hydride, Lithium-ion, or possibly Lithium-metal polymer.
But, is Lead (-acid) dead? Not if you observe the efforts being carried on by U.S. and European Lead-acid battery consortia. They want a Lead-acid hybrid in every garage and are willing to spend the money supplied by government, lead producers and battery manufacturers to prove they can be price and performance competitive. With hybrids using less than the full charge-to-full discharge range of a battery, the possibility of Lead-acid providing acceptable performance at an economical price may reopen the door of opportunity so cruelly slammed shut after EV failures. The road to success is far more difficult than merely packing today’s cells on the shipping dock. Lead-acid will have to prove itself on the not-always-friendly roads with performance equal to IC powered autos, while eliciting smiles on drivers’ faces in the showroom, at the gas pump and with acceptably infrequent visits to the service department.
The requirements of a battery in a hybrid vehicle are not the same as that of a SLI or a deep discharge battery. The SLI battery starts at full charge, emits a pulse of energy, and reverts back to a state of rest to receive a top off charge, never seeing significant depressions in state of charge unless it is in a poorly tuned Minnesota auto during an Alberta clipper. The deep discharge battery provides a lower current, but it does so until most of the stored energy is removed, after which it is usually fully recharged. The hybrid battery, while called upon for relatively short bursts of high charge currents to augment vehicle acceleration, must also be ready to accept high levels of regenerative energy from braking and spends most of its life in the region midway between full charge and discharge without achieving either condition. This profile is both good and bad, for the charge limit below full state of charge and above full discharge adds cycle life. However the hybrid battery is called upon for thousands of these partial cycles as the vehicle accelerates and decelerates. For the battery the unanswered questions are: “ under these new conditions what is the cycle life?” “Are there other effects which will reduce life and performance?”
Europe - A Choice Location
for VRLA Lead-acid Research for HEVs
If the numbers in the market research by Frost & Sullivan come to fruition, hybrids are set to capture one-tenth of the European market by 2015. Long term forecasts predict the market penetration rate to triple between 2010 and 2015. Julia Reuter of Frost & Sullivan said Toyota will focus on full hybrids while Renault and Fiat are likely to concentrate on mild hybrids. Honda is currently the only manufacturer selling mild hybrids in Europe, and with the launch of its Civic Hybrid in the spring of 2003 is likely to lead the mild hybrid market until 2005. Germany, France and the UK are expected to establish the strongest markets, with petrol-powered HEVs likely to take the lead.
Because the European Union is more focused on cutting carbon dioxide than nitrogen oxide emissions, the European market will follow the mild HEV route, compared with Japanese and North American markets that favor full hybridization. Full hybrids are unlikely to penetrate the European market before 2008, when French manufacturers Renault-Nissan and the PSA Group are expected to release full HEV models.
(Information is courtesy of Frost and Sullivan’s report, “Analysis Of The European Market For Full and Mild Hybrid Electric Vehicles.)
Can cost, including replacement, be isolated from perceived value? A lesson from the SUV market.
Assuming the hybrid provides the needed road performance the project bean counter will commandeer the spotlight adding that higher
ALABC Projects that VRLA Will Be a Key Player in Hybrid Vehicles
Last November the ALABC (Advanced Lead Acid Battery Consortium) announced plans to conduct its next phase of its research program (Jan. 2003 -Dec. 2005). The focus on this new phase is centering on high-rate partial state-of-charge operation for 36-Volt and hybrid-electric applications.
The need for VRLA Lead-acid to prove its capabilities is now. Already, Nickel-metal hydride is making its presence known in vehicles such as the Ford Escape HEV, the Honda Insight, the Honda Civic Hybrid and Toyota Prius. Toyota is so confident of its success of the Prius in the marketplace that it has stated that its goal is to well 300,000hybrids by 2005.
Dr. Patrick Moseley, the program manager for ALABC, states that VRLA Lead-acid must respond to this market now since Nickel-metal hydride has already taken a foot hold in these markets. “We are already seeing a positive market response to the introduction of HEVs powered by other battery chemistries. So, the need for the Lead-acid battery to respond to this incursion by Nickel-metal hydride has never been more urgent than it is now.”
ALABC’s Rob Putnam added, “Following the successful progress of RHOLAB, the team was encouraged to add a further application to the Foresight Vehicle Programme to adapt the results of the RHOLAB work to the potential demands of the vehicle with a 42Volt electrical system. This project will be carried out in a new phase of the ALABC and will be referred to as the ISOLAB42 program. This work will involve FIAMM and Exide Technologies.”
costs will make or break the project. In a product which lasts for more than 10 years and has a history of money. making follow-on service and repair, the deeper cost question involves an unquanitfyable overlapping of sticker price, performance, product image, and the acquisition of perceived owner/driver power and status. When the time comes to replace batteries what will they cost or will they be covered by a warantee?
Returning to the auto hybrid, there is no doubt that it will give higher gas mileage and reduce harmful emissions. Although theseattributes are the cornerstone of the hybrid design, average consumers usually pay lip service to ecological choices by others, but they don’t consider those values in their personal buying habits which show SUVs to be the most popular vehicle configuration with over a 40% market share.
There is no data suggesting that SUVs provide competetive cost effective, safety promoting, emission reducing or foreign-oil-dependence-reducing transportation. The perceived image of power and size creates the U.S. market for a population which has immense discretionary and recreational wealth. To this end, it makes sense to apply hybrid technology to SUV’s, for if gas consumption can be reduced by even a small percentage, it could make a significant reduction in the total oil used and pollution generated for a given number of miles traveled. The greater selling price added to the hybrid SUVs may be little hurt by the additional cost of components since these vehicles are in a much higher price category than average sedans and mini-vans.
Less than one percent of all the vehicles sold by Honda (Insight and Civic)and Toyota (Prius) last year in the U.S. were hybrids. However, between 2001 and 2002 hybrid sales increased by 77 percent.
Perhaps these numbers will soon escalate even faster if gasoline prices remain over $2.00/gal., especially in California. On March 23rd, in an article, “More Auto Buyers Going Hybrid,” LA Daily News, Amy Raisin interviewed the sales manager, Jimmy Camuso, of Power Honda of Valencia. He said, “ Six months ago, we very rarely sold a hybrid. Now with gas prices through the roof, I can’t keep them in stock. I’d say that of every ten phone calls we get now, two or three are for the hybrids.”
For hybrids, the greater question may be whether the added costs of showroom schooners will add to the customer required feelings of
power, status the image of cleaning up our economy and air. A massive public advertising and education campaign would be necessary to make any hybrids ‘trendy.’ If it could be done, the hybrid owner might show-off his/her car by parking it in the driveway rather than hiding it in the garage. This advantage could extend to the automaker which could offer the vehicles at a lower profit (or loss) to gain the image of being ecologically responsible. Although many would weep over reduced profits, the giant auto company could add ‘special’ pricing to other models to achieve its total profit and could shift public relations budgets. Government incentives based on reduced oil demand and pollutants to both car companies and consumers further improve the case for the production and sale of hybirds.
Hybrids of the Future
In 2002, hybrids made up less than one percent of all vehicle sales. About one third of the sales were in California; sales in the Midwest were almost nonexistent.
In discussing vehicles of the future, John Berry, a senior research director of Roper ASW and co-author of the book, The Influentials, states that the new vehicles will have to be “practical for families with kids.” Apparently, the soccer, football, basketball and hockey moms want to drive an SUV.
To suit American tastes, planned releases of HEVs will include the following:
DaimlerChrysler Dodge Ram Pickup 2005
Ford Escape SUV 2004
General Motors Saturn Vue SUV 2005
Chevy Silverado pickup 2004
GMC Sierra pickup 2004
Chevrolet Tahoo SUV 2007
These perception factors greatly complicate the cost issue, but after removing all this smoke, if Lead-acid can do the job at lower initial cost, even though it may require more vehicle lifetime replacements, manufacturers may figure ways to meet buyers’ price expectations while satisfying perceived needs.
The consumers’ lack of understanding regarding battery replacement issues is presently being played out in the Personal Digital Assistant (PDA) market where most new devices have factory-only replaceable Lithium-ion or polymer batteries. These little two to six hundred dollar handhelds give such great perceived image of status to the owner that the ensuing problem of the compromised or worn out battery will either require device disposal or a long out-of-service return to the factory for battery replacement. At the time of purchase, this is not considered as the buyer gladly parts with the money for the gleaming device which is usually called on to do the same as, or little more than, a pocket note pad and pencil. When replacement time comes, there maybe a bit of gnashing of teeth. Similarly, if Lead-acid hybrids require battery exchange at the nominal four years as experinced by the present SLI batteries, the owners’ preconceived understanding and the economics must be acceptable or public opinion could turn away from hybrids.
We will leave the cost argument with the assumption that Lead-acid life will be shorter than competing chemistries, (BD has no data on Nickel-metal hydride or Lithium-ion calendar life.) but Lead-acid’s subsystem cost must be significantly lower, too. Drivers have become used to replacing car batteries at about the four year point, so a first target for Lead-acid hybrids may be in the same ballpark. What the
Matsushita also has explored VRLA for mil HEVs.
At EVS 18 in Berlin, Ayako Hirao of Matsushita Battery Industrial discussed their work to satisfy the mild-HEV application battery system. They have developed a three monoblock VRLA battery (L-260 mm x W-173 mm x H-204mm). The 36V battery incorporates a number of features, including minimized electrode thickness and other structural enhancements for reduced internal resistance, as well as unique construction details which allow for effective heat transfer from the battery via cooling air flow through the battery structure and via integral cooling fins on the battery exterior. The battery has an output power capability of 8.6k. Under a typical HEV driving pattern life cycle, which incorporates 10 charging currents and 150 A discharge current levels, this battery achieves > 200,000 cycles.
replacement cost will be and who will foot the bill still needs to be determined both at an introductory level and a high volume level. Battery producers and car companies anticipate Nickel-metal hydride or Lithium-ion hybrid battery costs should sink to under $300/ kWh when volumes reach 100,000 packs per year. Such numbers, whether achievable or not, put the target for Lead-acid at something below this figure. Even murkier is the cost of the complete battery subsystem which includes the package, charging, temperature controlling and safety elements.
One might say that government incentive pressures have a major impact on the price and success of the hybrid, but in the long run, history shows that while government funding at the R & D level stimulates new technologies, it is not good at legislating economic supply-demand forces.
Why will the consumer buy a hybrid?
According to a 2002 study, and a repeated study in 2003, by Autobytel, 90% of on-line auto shoppers surveyed might consider buying a hybrid vehicle if it was offered in the exact same model as the car or truck they currently drive. Autobytel survey-takers said their number one reason for not buying a hybrid was the unavailability of a hybrid in the model they liked. Last year, only 10% indicated that they were willing to accept a differently styled or sized vehicle, and only 16% were most willing to compromise some performance features such as horsepower and acceleration.
In the 2003 survey, “model comparability (i.e. styling and features) outpaced performance comparability as the factor that would not compel them to buy - with only 36% of respondents citing ‘confidence that the hybrid will perform comparable to a traditional gas-powered car’ as their most powerful incentive to buy.”
Are consumers well informed about hybrids?
According to the 2002 study, most on-line car shoppers were simply uninformed about hybrids. About 44% of women indicated that they were ‘not very informed,’ or have only heard the word, ‘hybrid,’ for the first time when taking the survey. Women said their No. 1 reason for not purchasing a hybrid is simply not knowing enough about the vehicles. About 31% of the men responded having little or no knowledge. But by 2003, only a quarter of the respondents said they did not have the knowledge base on hybrids to consider purchasing them.
Would tax incentives help?
In 2002, only a small majority (9% of women and 13% of men) indicated that a tax credit of $1,500 or more would influence them to buy a hybrid.
Does environmental-friendless affect their decision?
43% of women surveyed in 2002 said they would be willing to pay an extra $1,000 to $2,000 for a hybrid which uses less fuel. However, only 34% of the men would be willing to do so.
Do hybrids link with national security?
In relation to national interests in 2003, 46% of respondents said they would be most influenced to consider buying a hybrid if they could get styling and features desired. (Ed. note: This might be interpreted as lttle to no perception of hybrids’ ability to reduce energy dependence with national security.)
Information is courtesy of Autobytel.com, “Research Area.”
EALABC to Prove Performance
Powering hybrid vehicles with commercially available Lead-acid batteries is being demonstrated by the European Advanced Lead-Acid Battery Consortium, (EALABC) Hawker Batteries Ltd., Provector Ltd, the University of Sheffield and the University of Warwick. Their program will incorporate Hawker Lead-acid battery packs in a direct replacement for the Nickel-metal hydride packs in a Honda Insight. This ‘Foresight hybrid will be a test and demonstration platform for Lead-acid in real world conditions.
Such an exchange is far from just being a quick battery swap exercise; because to be successful, the Lead-acid batteries must address a number of issues to prove the ability to compete as a hybrid power sink and source. While looking at the Lead-acid performance in the Insight, the observer must be cautioned to not overgeneralize on applicability to all hybrids, because as shown in the detailed analysis of Toyota Prius and Honda Insight by the National Renewable Energy Laboratory1, battery state of charge under the EPA’s Urban Dynamometer Driving Schedule (UDDS) varies considerably from the Insight to the Prius.
Why select the Honda Insight?
When comparing the battery in the Honda to Toyota’s Prius hybrid, the charge discharge requirements differ because of each system’s design configuration. The Toyota relies totally on battery power to begin motion and does not call on the IC engine until speeds of between 13-25 mph are achieved. The Insight battery provides motive power and simultaneously starts the engine as it begins to move. This difference will put unique demands on each battery system, so while the vehicle road driving profile may be the same for the two vehicles over a single course, each battery system will be called on for different charge/discharge performance.
The system Voltage is 144 Volts in the Insight and 273.6 Volts in the Prius. Because multiple cells have to be series connected to achieve the bus Voltage, only 72 cells will be needed provide the 144 Volts while it would take 134 series cells to feed the Prius. In a pioneer program, selecting the lower bus Voltage requirement limits the risk imposed by cell failure and conditioning. Then too, the lower nominal energy of 936 Wh also means less cells than that required for the 1778 Wh of the Prius. With less cells, the challenge becomes more manageable. It appears to be a walk-before-you-fly approach.
Using the Base Method, all component costs are treated at the cost of labor and materials. Manufacturer and dealer- markups are applied to all component costs. Costs for vehicle development are also added. Information was gathered through focus groups in Los Angeles and Orlando.
The Focus group participants providing their views in the study were told to assume that HEVs had been sold for 5 or more years and that they were safe, reliable and had the same performance as conventional vehicles.
(Data is from EPRI study, “Comparing the Benefits and Impacts of Hybrid Electric Vehicle Options for Compact Sedan and Sport Utility Vehicles,” 07/02)
Why select the Hawker Cyclon Cell?
The cell itself is important both as a single cell and as a cell within a system of cells. To simultaneously invent a new cell and qualify it in a hybrid application is risking too much, so the EALABC is calling on the Hawker Cyclon sealed design which uses pure lead thin plate grids and enjoys decades of successful performance. Hybrid operation asks for high power, both during discharge and during dynamic braking. Simultaneously, hybrid start/stop operation places the requirement of great cycle life on the cell. The best operating region for such give and take operation is in a partial state of charge. Failure mechanisms2 in this state will be one of the outcomes of the Foresight Program so that even more robust batteries can be built. Early gassing which could reduce cell capacity will be reduced with advanced separator materials. Sulfation reduction of the negative plate will be pursued with improved carbon materials. Recharge resistance reduction is facilitated with the cell twin tab configuration and will be further pursued with revisitation of the material purity issue and the possibility of a synthetic expander.
The Honda Insight was the first HEV to be available for public purchase . The two-seat sport care was introduced across the U.S. in late 1999. The EPA mileage ratings are 61-mpg city/70-mpg highway. The Insight is powered by Honda’s patented Integrated Motor Assist (IMATM) system, which combines a 1.0-liter, 3-cylinder gasoline automobile engine with an ultra-thin electric motor.
In test1 by the National Renewable Energy Laboratory, the amount of battery (Nickel-metal hydride) energy used by the electric motor to assist vehicle propulsion during acceleration was 3% of the fuel energy used by the gasoline engine. This level occurred during the aggressive driving cycle. (Photo reprinted by permission of the European ALABC from the ETIC presentation by Allan Cooper)
The Lead-acid cell selected for the Foresight hybrid has a successful history coming from the original Gates pure-lead cylindrical cell of the late 1970s. The design has a starved electrolyte and 99.99% pure lead grids with 0.6% tin added for deep discharge recovery. The separator is absorbing glass mat. The plates are pasted with lead oxides and assembled with a relief valve in a polypropylene case and metal can. First introduced by Gates in the late 1970s and then purchased by Hawker Siddley in 1988, the company was recently acquired by EnerSys and the battery is still sold under the ‘Hawker Cyclon’ name. (Graphic reprinted by permission of Enersys)
How detailed must the testing be?
The complicated operation of the battery does not allow simple bench life cycle definition such as that from the PNGV Power Assist Life Cycle and the EUCAR Power assist Life Cycle, which only defines current with time for a typical cycle. From the rich base of dynamometer and road testing, specifically for the Insight, more representative bench test profiles are established and find definition in the RHOLAB ‘Real-data’ definition, making bench test results more representative of real world operation. This more realistic bench test is another of the walk-before-flying steps in a scientific approach to quailfy ing Lead-acid for hybrids.
The final test is on the open road, combining the demands of charge and discharge with the harsh realities of actual stop/go acceleration/deceleration, overlayed with temperature, shock and vibration. Not only will the batteries see calm smooth roads such as those in beautiful Thousand Oaks, California, but also the bone-shocking potholes experienced in Chicago, Illinois’ working streets. If hybrids are to be ubiquitous, they must eventually function in Minneosota’s forty below (Faherenheit) winter wonderland and Palm Springs’ 120 degree (Faherenheit) sauna. Only with a real world Lead-acid hybrid can all these conditions, already accommodated by today’s ICE autos, be experienced.
To increase the high current capability of the E size design, dual tabs on each end of the cell have been added (below), resulting in the improved performance shown above when cycled under the Rholab profile. (All graphics reprinted by permission of the European ALABC from the ETIC presentation by Allan Cooper)
Where does 36/42 Volts fit in?
It is most likely not a curiosity that 144 Volts can be made up of four 36 Volt modules in series for the Insight. From the experience to be gained in this high Voltage application, the 36 Volt modules will gain valuable experience for the 42 Volt bus which it is anticipated will replace the 12 Volt batteries completely by the year 2010. If validation can show the Hawker 36 Volt modules suitable for the Insight, it will go a long way to open the doors for use in 42 Volt autos, whether hybrids or non-hybrids.
This data shows that conditioning Hawker cells produces nominal 10% increases in cell capacity within the 19 cell pack.While in the Rholab test phase, after each 10 cycles, the pack is stripped and each cell undergoes the following individual conditioning profile:
1. Discharge at 1.53 A to 1.7 V @ 25 0C to remove remnant capacity
2. Charge at 2.45 V. at 10 A current limit for 16 hours @25 0C.
3. Discharge at 1.53 A to 1.7 V @ 25 0C to measure capacity
4. Charge at 2.45 V., 10 A current limit for 16 hours @25 0C.
5. Impedance measurement with 90 mA galvanostatic at 10 frequencies
in the range of 0.01 Hz to 10 kHz.
By early April, the pack had reached 261 Rholab cycles with no reported failures. (Graphic reprinted by permission of the European ALABC from the ETIC presentation by Allan Cooper)
A critical failure mode is to have one cell fail in a series string.. A single cell failing to a high resistance state would eleiminate the module and the entire supply. To accommodate failure possibilities and off-pack conditioning, the Rholab module has 19 cells, allowing one cell to be off the circuit for conditioning. By allowing any of the cells to be off the bus, it appears that the pack could accommodate a single cell failure and still provide full 36 Volt operation. For such intelligent control, the module dedicates a separate microprocessor to each cell on the pack, complicating the hardware, but providing reliability and honing the individual cell with on-board conditioning.
The Hawker cells with tabs on both ends are electrically and mechanically mounted to printed circuit boards on each side to make assembly convenient to minimize distribution power losses and to facilitate charge acceptance and discharge performance of the cells.
Nineteen, 2 Volt, 8 Ah cells are assembled into each pack, allowing one of the cells to be undergoing a conditioning cycle while the others operate. The cell microprocessor and related circuitry reside on the board next to each cell. When compared to the 6.5 Ah capacity of the original Insight batteries, the higher capacity of the Hawker cells may change the way the batteries contribute to the hybrid cycle.
When assembled into the casing as shown at the the left, a cooling fan is attached to facilitate airflow around each of the cells.
The group of four modules in the pack occupies slightly more space than the original Nickel-metal hydride pack which fits inside the straight line of the IMA frame. To accept the Lead- acid modules, the Foresight vehicle frame has to be modified, using additional space over the spare wheel ordinarily used as a small storage compartment in the Insight. (Graphic reprinted by permission of the European ALABC from the ETIC presentation by Allan Cooper)
Coordination, standardization and safety
The combination of usability, cost effectiveness and safety for any technology is expanded when there is industry-wide coordination and standardization. For Lead-acid in hybrid applications, the work done and being done to facilitate 42 Volt automotive systems will improve its focus in providing product. For years now, the Industry Consortium on Advanced Automotive Electrical/Electronic Systems facilitated by the Massachusetts Institute of Technology with Dr. Thomas Keim4 as its Principal Reserach Engineer has made 42 Volts a coordinated rather than a fractionated effort.
Other Potential Lead-acid Batteries for HEVs
Eagle-Picher Industries, Inc., a diversified manufacturer and marketer of advanced technical and industrial products, has announced the formation of a joint venture with Horizon Batteries, Inc. (formerly Electrosource). The joint venture will develop, manufacture and distribute a breakthrough, high performance sealed Lead-acid battery.
This new battery is based on a patented, woven-grid process technology that reduces internal impedance for greater efficiency, faster recharge and higher cold cranking power. Eagle-Picher states that the new battery will have the highest specific energy (>45 Wh/kg) of any Lead-acid battery on the market today. It will be ideal for the emerging hybrid electric vehicle (HEV) and the industrial electric vehicle (IEV) markets in which high power, lightweight, long life and quick recharge time are critical.
Production of the Horizon battery was scheduled to begin by late April this year. The product will be made in both China and the United States. To fully support Horizon, Eagle-Picher will significantly expand their global manufacturing, sales and marketing organization. (Photo is courtesty of Eagle Picher.)
Another contender for powering hybrids might be the Thin Metal Film Lead Acid battery by GP Batteries. Purchased in December 2001 from its initial developer, Bolder Technologies, GP saw its initial application as a superior emergency starter battery for the automotive industry. However, for the longer term, GP Batteries says the technology holds promise in high-powered applications as well as for the emerging hybrid EV and 36-Volt automotive batteries. (photo reprinted by permission of Eagle-Picher Industries, Inc.)
Also in the 36/42 Volt realm, is the American Society of Testing Materials (ASTM) which has formed a new subcommitee D09 to develop new test methods and standards for conducting tests in road vehicle applications. For mor details on D09, see the Questions and Answers provided by George Zguris in his ‘Ask George’ column added to our website this month.
Other ASTM and Underwriters Laboratories (UL,) and Society of Automotive Engineers (SAE,) Institute of Electrical and Electonic Engineers (IEEE) testing standards will facilitate development and safety of the higher Voltage batteries.
A word of caution regarding safety must be applied to the impression of standards regarding the electrical circuits of hybrid vehicles. While battery modules generate 36 Volts, the
Competition for Hawker and their VRLA battery
Using a Nickel-metal hydride batteries, Honda is warranting its Civic hybrid battery pack for 8 years/80,000 miles. Thus, the thought of a potentially high cost (several thousand dollars) replacement pack is not so worrisome to the consumer.
Toyota, also using a Nickel-metal hydride battery pack, is providing a 100,000 mile warrantee . However, “Toyota predicts that the Prius’s battery will last the lifetime of the vehicle.” (“Are Hybrid Vehicles Worth It?” by Lester Lave and Heather Maclean, IEEE Spectrum, 03/01)
GM’s hybrid engines are going to be built with standard Lead-acid batteries which are at least 25 percent less expensive than Nickel-metal hydride batteries. GM plans to produce a hybrid version of its Saturn Vue SUV in 2005.
Ford has selected Sanyo Electric Co. Ltd. as their “exclusive” supplier for the 300 Volt Nickel-metal hydride traction battery pack and battery controller for their Escape SUV HEV, debuting this year.
In discussing Lead-acid two years ago at the Advanced Automotive Battery Conference, Fritz Kalhammer of the HEV working Group said, “Key issues surrounding possible HEV applications are whether the technology (Lead-acid) can survive well over 100,000 shallow cycles and also meet the calender life requirement of 10 years or more; the achievement of the cost goal is likely to be a challenge as well.”
total bus Voltage in the Insight and Prius are much higher. Forty-two Volts was subjectively selected as a new automotive bus standard because it is an upper limit of acceptable working Voltage where a careless maintenance/repair person should not be dangerously shocked. When two or more 36 Volt modules get tied in series, the total bus Voltage goes into the region beyond casual safety concerns for which the 42 volt battery module cannot be held liable. At this point, the higher Voltage must be addressed with standards beyond those of 42 Volt systems, and only allow limited access by trained professionals to eliminate the shock hazard which could be fatal. (Ed. note: electrical shock hazard is not easily specified. From the viewpoint of applying electricity to the skin of a normal person, the variable conductivity of the skin is usually the greatest barrier. At 42 Volts, to achieve a current of 10 mA, sometimes identified as the threshold of ‘can’t let go’ current, the body/skin resistance would have to be 4,200 ohms. Assuming internal tissue to be very low resistance and skin as a series element, each contact point would be 2,100 ohms, not unachievable with hands wet with sweat or contaminated water. If these numbers do not capture the reader’s interest, consider first that the trip limit of a ground fault interrupter is 5 milliamps of fault current and if that is not enough, UL Standard 544 limits patient contact leakage of medical devices to the AC line (and ground) to 10 microAmps. The bottom line here is that even at 42 Volts, a person should understand and take standard precautions to eliminate the possibility of electrical shock.)
John Olson, Vice President of Technology - Boundless Corp., states that “VRLA batteries have shortcomings in a high power HEV application, where typical cycling at intermediate state of charge and large discharge and charge current pulses are encountered. In spite of their limitations, the size of the batteries required for HEV buses and the economics of batteries nearly demands that the application be met with high power Lead-acid batteries.” Dr. Olson will be speaking on this topic at the conference, “Advancements in Battery Charging, Conditioning, Monitoring & Testing,” in Denver on June 11th and 12th.
Let the Games Begin
With the Insight and Prius, Nickel-metal hydride has struck a feasibility stake in the ground for hybrid power, but its success has not eliminated competetion because further experience including data on self discharge and calendar life along with lower production costs need to be determined. Lithium-ion and Lithium metal polymer need high visibility successes to make them a contender. From the work Lead-acid hybrid researchers have completed, have in process and have planned for, results may show a bright future which may be due to more than just cleaner air.
General Motors Corp., Vice Chairman Robert Lutz doubts that General Motors (GM) would be able to sell one million hybrid (gas/electric) vehicles by 2007. He reasons that with the high costs of production the vehicles may not be profitable to build because many consumers are not willing to pay a premium for them.
Earlier this year at the Detroit Auto Show, CEO Rick Wagoner announced that by 2007 GM would have manufacturing capabilities to produce three different hybrids with volumes as high as one million a year. However, in referencing hybrid development, Mr. Wagoner also added a conditional clause, “if the market wants them.”
1.) Battery Usage and Thermal Performance of the Toyota Prius and Honda Insight for Various Chassis Dynamometer Test procedures. National Renewable Energy Laboratory
2) High Rate Partial State-of-Charge Operation of VRLA Batteries. BCI Session on 42 Volt Battery Systems, 2002
3.) The Development of a Reliable Highly Optimized VRLA Battery for HEV Applications. The EVAA Electric Transportation Conference, 2002
4.) Technical and Cost challenges for 42 Volt Implementation, BCI Session on 42 Volt Battery Systems, 2002.
5.) From a long lost Latin document which used the word ‘Tinquor’ in a way which could be loosly interpreted as ‘tinkerer,’ making the phrase ‘Those who mess with higher Voltages should use caution, lest they fall prey to being knocked on their posterior regions.’