Battery Options for Hybrid Vehicles and Electric VehiclesBy Tom Bartley • Apr 30th, 2009 • Category: Battery Technology for Hybrid and Electric Cars
The Institute of Electrical and Electronics Engineers (IEEE), the Society of Automotive Engineers (SAE), and others periodically publish magazine articles that provide update summaries on the leading candidate energy storage technologies. Research and Development (R&D) and production is on the upswing getting a kick from increased funding and tax credit support for electric vehicles (EVs) to reduce oil consumption and the generation of CO2 and other air quality contaminants. The American Recovery and Reinvestment Act of 2009 (ARRA 09) has designated $400 million for electric transportation technology and $2 billion for advanced car battery manufacturing.
Batteries or battery packs can make or break a hybrid or electric car. Here’s a look at the different battery options and their characteristics together with notes on key manufacturers. The list is in no particular order.
Lead-acid or valve regulated lead-acid (VRLA)
- Most widely used for starting engines.
- Cheapest option.
- Good power capability.
- Low energy density making it too heavy or too low capacity for some applications.
- Reduced capacity at low and high temperatures.
- Lead must be recycled.
- Good shelf life.
- Poor cycle life unless SOC (state of charge) range is limited during operation.
- Improvements are still being developed, look for various “hybrid” energy cells.
- Requires desulfation charge to extend the life an extra 25 to 50%.
- Deep cycle versions are used for electric vehicles to keep the cost down.
Nickel Cadmium (NiCad)
- Is going away because the biggest problem is the recycling of heavy metal cadmium.
- Has a memory problem without deep cycling.
- Requires watering maintenance.
- Average cycle and shelf lives, power and energy densities, with reasonable temperature performance and cost.
Nickel Metal Hydride (NiMH)
- Today’s standard for power and energy capacities and densities.
- Millions of packs in use.
- Shelf life requires charge maintenance.
- Cycle life several times better than lead-acid, but SOC range must be limited during cycles to attain HEV and EV life goals.
- Performance falls off at low temperature.
- Cooling is required for high current charge and discharge cycles.
- Panasonic is dominant producer and Toyota Prius dominant user.
- U.S. producer Cobasys has yet to prove it can supply good reliable packs.
Lithium Ion (Li Ion)
- High energy and power capacities and densities (lightweight) ideal for hybrid and EV applications. Ten-year shelf life and extremely high cycle life if SOC range is limited (40% to 70% or tighter); some low temperature performance drop off. Look for widespread production use by the middle of 2010.
- Most of the world supply of lithium carbonate source material is located in Bolivia, Chile and Argentina. Early abundance reports suggested the supply was insufficient to supply the potential global demand. Later reports suggest otherwise.
- Widely used in small electronics, early chemistries had a potential thermal runaway problem that led to a few explosions. More recent recipes must pass rigorous cell testing and have all but eliminated the problem, however there remains some residual concern about heat generated in pack designs.
- Nissan now in partnership with NEC to develop and produce an in house pack design for an EV starting with fleet deliveries in 2010 and the general public in 2012. A 26-minute “quickie” is one of the charging options. Nissan and others will offer pack leasing to control fears about the cost of replacing a failed battery pack.
- Magna Steyr in Austria is in volume pack production using A123 batteries for some European vehicle manufacturers. A123 is also developing some of its own pack designs.
- Toyota delayed introducing Li Ion packs, but may do so in their new plug-in Prius.
- Valence Technology Inc in Texas is in high volume production for electric bikes and scooters and has supplied larger packs to a limited number of plug-in hybrid school buses. The one negative is that these batteries tend to be a bit pricey. But I guess for extended EV range you get what you pay for at least for now.
- ThunderStruck, a Chinese company, is in high volume low cost cell production with limited quality control; about 10% of delivered cells are bad.
- Altairnano is leading the way in fast rechargeable cells with the lithium titanate chemistry. They give up some energy density to gain fast charging and high cycle life.
Nickel Zinc (NiZ)
- Powergenix, headquarters in San Diego and production in China, offers AA and sub C size cylindrical cells with D size in preproduction testing.
- The primary application so far is hand held power tools where they are a less expensive alternative to Li Ion and NiMH cells.
- Higher energy density than NiMH because of higher cell voltage of the chemistry.
- Easy recycle handling.
- Apparently good shelf life.
- Good efficiency (low cell resistance).
- Good lower temperature performance.
- Powergenix built a Prius replacement pack (it needs more R&D) and may find a niche market as a less expensive replacement pack supplier.
- These devices have extremely low internal resistance (~0.2 milliohm) per cell and extremely high capacitance (~3000 Farads) per cell, making them ideal high power devices.
- However, they are generally low energy and need to work with a battery to achieve any driving range.
- Ideally the combination of batteries and ultracapacitors offer the best of both worlds, but the voltage versus SOC profiles don’t match and there has been very little development of large pack combinations.
- Hybrid cells may offer a way out.
This list represents a snapshot of various energy storage technologies available for upcoming hybrid and electric cars. Development in the industry is expected to move quickly in the next few years due to demands of the market and with the help of government regulations and financial stimulus packages. There are several major battery conferences on battery technology every year, both in the United States and around the world. For additional details, your favorite Internet search engine may be your best window into this fast moving, and critical, industry.
Tom Bartley is an industry veteran with 30 years of experience in general business, marketing, project and product management, and engineering research and development. Mr. Bartley provided executive management support including technical and business oversight to heavy-duty hybrid-electric prototype projects as they evolved into production. He developed cost models for energy storage and fuel savings, and power models for ultracapacitor packs. Mr. Bartley is well known throughout the industry of heavy-duty hybrid-electric buses and trucks, having delivered many papers and presentations since 2003. Mr. Bartley maintains a blog at TomBartleyIdeas.com. Follow twitter.com/TLBartley.
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