The majority of hybrid car battery packs use nickel-metal hydride (NiMH) batteries. Currently, NiMH batteries are a reliable energy source of energy for hybrids, have long lives and are relatively inexpensive. In fact, some of the lower-power battery packs can cost as little as $600. Of course, batteries capable of more power will cost more and high nickel prices and a limited potential for cost reduction has manufacturers thinking about alternatives.
The lithium-ion (Li-ion) battery is one of those alternatives. Many people are now familiar with lithium-ion battery technology through their use in various electronic devices. If you own a laptop or listen to music on an MP3 player, chances are it's powered by lithium-ion batteries. They're small and light, making them attractive to the rechargeable battery market. For hybrid cars, they offer high-power and high energy for their weight and volume, and they're more efficient than nickel-metal hydride batteries.
It's still a little early for lithium-ion technology in hybrid cars -- its reliability is unproven, and the cost is higher than that of NiMH technology. If more testing and investment continues, however, you might see smaller and lighter lithium-ion battery packs in hybrid cars very soon.
If lithium-ion batteries don't work out, a cheaper battery -- one made from surprising materials -- could become a possibility. Read about it on the next page.