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5 Ways Hybrid Battery Packs are Being Improved

With many drivers uncertain about hybrid car battery packs, researchers are looking for ways to improve the technology. See more electric car pictures.
AP Photo/Shizuo Kambayashi

The battery pack in a hybrid car is arguably one of the most important parts that make it go. As you may already know, a hybrid car makes use of a combination of an internal combustion engine and electric motor. While the gasoline that provides energy for the engine is stored in a fuel tank, the electric motor gets its power from a different source.

A battery pack stores and supplies the energy necessary to power a hybrid car's electric motor. Without the chemical reactions that happen inside a battery, the technology that makes a hybrid vehicle a hybrid simply wouldn't be possible.

But despite the battery pack's prominence and importance in hybrid vehicles, sometimes they get a bad rap. Skeptics of hybrid technology point to several shortcomings associated with these car batteries. For example, they don't provide enough power, and therefore hybrid cars are slow; the batteries are too heavy, which counteracts a hybrid's supposed fuel economy; the materials many batteries are made from, like lead, are harmful for the environment and go against the familiar "green" claim.

The good news is this hasn't deterred battery manufacturers from trying to make their product better. On the contrary, there happen to be many ways that battery packs are undergoing improvement. In no particular order, here are five ways that hybrid battery packs are being improved.

Less Expensive Batteries

One of the biggest turnoffs for potential hybrid car buyers is the high cost of a replacement battery. Battery packs, which typically cost about $3,000, represent a significant percentage of the total vehicle cost. The fear of battery replacement due to failure has led many drivers to hold back on making a hybrid car purchase.

But battery prices -- along with battery failure rates -- have plunged since the beginning of the decade. To phrase in that a different way, batteries are now less expensive and last longer than they did in the past. In 2001, battery replacement in a hybrid car cost about $10,000. Recently, however, Honda has cut its battery replacement price from $3,400 to $1,968. In the near future, Toyota also plans to slash its replacement costs from where it stands now at around $3,000. Also, Toyota's out-of-warranty battery replacement rate has plummeted from about 1 percent for the first generation Prius to 0.003 percent for the second generation.

Could hybrid cars eventually get power from the same kind of battery you find in an iPod? Find out on the next page.

Lithium-ion Batteries
The same technology that powers an iPod could make its way into hybrid car battery packs.
AP Photo/Shizuo Kambayashi

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.

New Lead-acid Battery Advancements





Longer Battery Life
Customers have shown concern over hybrid battery pack life spans, but failure rates are extremely low and car companies develop batteries that last the life of the car.
AP Photo/Shizuo Kambayashi

Rumors of short battery life spans and high failure rates have scared off potential hybrid car buyers for years. Many hybrid customers ask if they'll eventually need to replace the battery pack and exactly how long they can expect the battery to last. Is it a matter of four years? Five years? Perhaps seven years?

The truth is, car companies guarantee their hybrid battery packs for the life of the car, which in recent years has been around 100,000 miles (160,934 kilometers) or more. And the warranties on the batteries generally last for eight years or even longer, in some cases. In other words, if the battery did fail for some reason while the car was still covered under warranty, the manufacturer would cover the replacement cost. The battery in the 2010 Toyota Prius, for instance, has a 10-year, 150,000-mile (341,402-kilometer) warranty.

While batteries are extending their life spans, they're also cutting back on the pounds. Read about batteries trimming down on the next page.

Less Weight

Heavy batteries are the bane of many fuel-conscious drivers' existences -- the more weight you have in your vehicle, the more energy you'll need to move forward. That's why people tell you to unload any belongings from your car's trunk and back seat if you really want to save at the pump.

Recognizing this problem, many researchers have looked into making hybrid battery packs much lighter. A group at the Massachusetts Institute of Technology (MIT), for instance, has found a way to make lithium-ion batteries both lighter and faster. The original problem with lithium-ion batteries was their relatively slow release of energy. Scientists thought lithium atoms were moving too slowly through the battery material, but the MIT researchers think it might be the nano-scale size of the technology that's making it difficult for ions to travel.

A lithium phosphate coating helps speed ions along, making it easier for them to quickly reach the battery terminal. The new battery material also stops the packs from degrading as much, which means that manufacturers can keep the sizes of the batteries much smaller than before.

For lots more information on hybrid cars and battery technology, follow the links on the next page.


How the Toyota Hybrid X Works

How the Toyota Hybrid X Works

The Hybrid X concept car from Toyota sparked interest in another Prius-like model. Learn how the Hybrid X evolved and what Toyota's plans are for it.

Related HowStuffWorks Articles


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  • Hamilton, Tyler. "A Cheaper Battery for Hybrid Cars." Technology Review. Massachusetts Institute of Technology. Jan. 24, 2008. (April 13, 2009)
  • "Behind the Hidden Costs of Hybrids." Sept. 28, 2008. (April 13, 2009)
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