Report From AABC 2006
At the time of the first AABC (Advanced Automotive Battery Conference) in Las Vegas in 2001, it was widely expected that the 12-volt automotive battery (14-volt PowerNet) would progressively be replaced by a 36-volt battery (42-volt PowerNet), in order to cope with increased electrical loads. Since then there have been improvements in the output available from high output 14-volt alternators, and also some success in engineering lower power solutions. It was also found that the total cost of switching from a 14-volt to a 42- volt PowerNet would be too high for mass market automobiles. A general switch from 14-volt (12-volt battery) to 42-volt (36-volt battery) for conventional automobiles is now regarded as extremely unlikely.
The emphasis has now switched to hybrid electric vehicles (HEV), the best known of which is of course the Toyota Prius. At this years AABC meeting, the greatest interest was in high voltage hybrid electric vehicles and plug-in HEV's. Once again, Menahem Anderman – the Conference Organiser – provided an excellent "road map" of the range of hybrid-vehicle configurations:
My own background is in lead-acid battery technology, so it was disappointing to hear that lead-acid will have a limited application in the HEV market. It is likely that it will be suitable for micro/mild hybrids only, but most of the current HEV developments are for strong hybrids. NiMH is the only clear battery choice for current vehicles and for new vehicle developments through to 2010. However, from 2010 onwards, Li-ion may start to replace NiMH. The high price of nickel will continue to have an impact on the cost of the NiMH battery, whereas eventually the Li-ion battery should see cost reductions and will be able to compete with NiMH on price. There are still concerns about Li-ion, partly technical, partly safety. NiMH still has issues with self-discharge and low temperature performance. Even with strong hybrids, a 12-volt lead-acid battery may be used for starting, because of the poor low temperature performance of NiMH and Li-ion in comparison with lead-acid.
Panasonic (Matsushita) and Sanyo are the major suppliers of NiMH batteries for existing hybrids. They are also developing Li-ion batteries for HEV's. These are claimed to have a longer life and higher power performance than currently available Li-ion batteries. However, the existing manufacturers of small Li-ion cells/ batteries (e.g. for consumer applications) see the potential market for Li-ion batteries in hybrid electric vehicles as unimportant compared with their existing markets.
A great deal of research effort is being poured into improved Li-ion battery systems, particularly in respect of reliability and safety. For example, A123 systems have a version of the phosphate based lithium ion battery technology, in which an aluminium electrode inside the battery is coated with nano-scale particles (a few hundred atoms in size), of lithium metal phosphate. They claim that this battery has a greater tolerance to overcharge and improved safety. However, the system cost and complexity for a high voltage HEV is still not clear.
One of the most interesting sessions was the one on plug-in hybrids. Interest in this concept seems to have increased significantly in recent months. A larger battery is needed, dependent on the electric-only range requirement e.g. for 20m or 40m range. This adds cost and weight and may require a compromise with passenger and/or luggage space. The plug-in ability can offer the benefits of significant fuel savings, dependent on the duty cycle. The owner does not have to utilise the plug-in feature, but any fuel saving benefit will be lost if he does not do so. Also, from the viewpoint of overall efficiency, it may be better to use blended power throughout the drive cycle, rather than all electric for the first 20 or so miles. Battery life also becomes more of an issue if the battery is regularly deeply discharged. This is an interesting concept, and has gained US Government funding for further development. However at the moment it is not clear whether a cost/ benefit analysis will show a net benefit for this concept compared with existing strong hybrids. Certainly Toyota seem very cautious about this concept. Toyota's view on Plug-in hybrids is that they may offer reduced life cycle CO2 and reduced fuel consumption. However, to reach this vision, breakthroughs in battery technology are needed, including capacity, durability and cost. Toyota believe that with the state of the current technology, Plug-in HV is not commercially or technically feasible.
This Conference was very much geared to US experience and markets. Neither USA nor Japan has a significant market for diesel automobiles, whereas in Europe up to 50% of the market is for diesel engine vehicles. Some studies in the UK have even shown that a diesel engine auto can show fuel economy equivalent to a similar sized hybrid. For US automakers, the strategy is also to develop hybrid power trains for the least fuel-efficient vehicles rather than for the smaller, high volume conventional autos. My personal viewpoint here in the UK is that I really cannot understand the American love affair with gas-guzzling SUV's. However, the point was made that the American love affair with large SUV's is unlikely to end any time soon, in spite of rising gas prices. In order to gain a "greener" image the major automakers are developing hybrid SUV's with better fuel economy than conventional SUV's. However, the hybridisation of the power train of SUV's is also aimed partly at improved performance, not just fuel economy.
Toyota are still the market leader in the development of electric vehicles. They estimate sales of 1m vehicles p.a. by early next decade. The Toyoto Prius is the best known, and the Lexus RX 400h, Highlander Hybrid, GS 450h, and Camry HV have all been added to the HEV product line-up. The GS 450h has been designed with performance in mind rather than fuel saving.
Ford HEV sales could be 250k/y by 2010. Sales of the Honda Insight have been much lower than the Toyota Prius (~50k/y). Production of the Honda Insight will cease in September, they are planning to replace it with a new, hybrid-only model. Other automakers are lagging way behind Toyota in HEV development, but General Motors, DaimlerChrysler and Nissan all have HEV plans in the pipeline.
The chart below from Anderman's presentation shows the HEV battery market growth from 2001 – 2009:
It can be seen that the current market is dominated by Panasonic EV Energy (PEVE) NiMH and Sanyo NiMH. By 2009, these two manufacturers of NiMH batteries will still be dominant, but there will be some market penetration from Li-ion, manufactured by PEVE and NEC. Cobasys NiMH may also have a small market share.
Finally, Ragone charts showing Specific Power vs. Specific Energy for different battery systems are always interesting, and several presentations included Ragone plots. I have included a screen shot from the JCI/SAFT presentation.
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