2nd lives for EV batteries could cut prices

Lithium ion battery packs that power some electrified vehicles could end up feeding juice into the electrical grid -- a development that could cut EV ownership costs.

Although the electrified vehicle market is still in its infancy, automakers and power companies are experimenting with second-life uses for the batteries once they're retired from the road.

Battery experts say the shelf life of a lithium ion battery in an EV is around 10 years, and automakers such as General Motors and Nissan are pondering what to do with still-useful units.

Used lithium ion batteries have around 70 percent of their capacity remaining at the end of their vehicle stints. If automakers retained ownership, they could then sell the batteries after they are no longer usable in vehicles, recouping part of the initial battery cost.

"From an environmental picture standpoint, you need to think about the sustainability of everything you're doing. You need to focus on the broader picture," said Pablo Valencia, GM senior manager of battery lifecycle management. "What we're doing right now is preparing for that broader picture -- getting awareness up, both from a customer standpoint and also an industry standpoint, so that the energy storage industry is thinking about secondary use."

GM and Nissan say having secondary uses for Chevrolet Volt and Nissan Leaf batteries can help market the vehicles and add to their residual value, but it's still too early to tell if consumers will see lower prices. A GM spokesman said the company is figuring out how a potential business model would work.

It's possible, the spokesman said, that GM could "provide some sort of monetary payment" to the consumer once the battery is no longer useful in a vehicle. But nothing has been finalized.

"Ideally, EVs become more attractive to the consumer from a pricing [standpoint], or secondary option that might be available to them," said Brad Smith, director of 4R US at Nissan North America.

Amid the ongoing r&d, potential used-battery markets are taking shape.

A bank of batteries that once propelled the Volt or Leaf is capable of providing backup emergency power to homes after storms.

Utility companies could use the batteries, grouped together in single storage systems, to make energy grids more efficient by having them store power during times of low electricity use and discharge it to homes and businesses during peak hours.

Renewable energy sources such as solar and wind farms could use groups of batteries to supplement power output when clouds temporarily block sunlight or when wind speeds dip.

There has been "a lot of activity in renewable power in the last decade or so, and there's an increasing interest in incorporating batteries into those systems to improve their power profiles," Smith said.

GM and Nissan are working with ABB Group, a power and automation technology company, to develop energy storage systems using Volt and Leaf batteries. Nissan also formed 4R Energy Corp., a joint venture with Sumitomo Corp., to research second-life battery uses.

ABB said it has had preliminary discussions with other automakers, but declined to disclose which ones.

In the next decade, Valencia said he expects to see an infrastructure in place to retrieve used EV batteries, verify their performance and reconfigure them for grid functions.

"That's where the world will be," Valencia said. "People will understand how to use them."

In November, GM and ABB demonstrated a prototype of a modular unit that can power three to five homes for two hours.

Five used 16-kilowatt-hour Volt batteries were used in the prototype, which powered the audio/visual equipment in a tent during the GM Electrification Experience in San Francisco.

ABB's Energy Storage Inverter system can use Volt batteries to output 50 kWh of energy.

The plan is for partner Duke Energy, one of the largest U.S. electricity providers, to test a unit on its grid. The Charlotte, N.C., utility company serves 7.2 million customers in six states in the Midwest and Southeast.

"The unit is going to be connected to the grid of the utility," said Pablo Rosenfeld, ABB's global product line manager of energy storage modules. "At this point of development, we [also] see potential to be sold to commercial business or small retail stores."

GM and ABB joined forces in 2010, while Nissan partnered with ABB in 2011. Rosenfeld said ABB has completed the first phase of testing on the Leaf's 24-kWh battery.

While GM, Nissan and ABB focus on used batteries, Portland General Electric is putting fresh lithium ion batteries similar to those in EVs in a substation in Salem, Ore.

The Salem Smart Power Center, slated to go live this month, will support 500 residential, business and commercial customers, according to a company spokeswoman.

Portland General Electric has been in contact with automakers about secondary uses for EV batteries, said Charlie Allcock, director of business development for the company.

"I think the potential is there, and that's how we're looking at it. It's in the category of 'good idea,'" Allcock said. "In the meantime, our stance is as soon as we can get our hands on some of these batteries, we'd like to start testing their feasibility. There aren't that many used EV batteries around."

So why are batteries considered end of life when they have so much capacity left?

It comes down to aging batteries diminishing EV range, along with their declining ability to accept regenerative braking energy and deliver power to the electric motor, said Steve Clark, Chrysler's senior manager in electrified powertrain engineering.

"At some point in time, it becomes difficult for the driver to achieve their expectations out of the vehicle with respect to keeping up with traffic and merging onto freeways and that kind of stuff. That's where the end of life is effectively happening," said Clark, who also is Chrysler's representative to the U.S. Advanced Battery Consortium's management committee.

The consortium -- made up of the Detroit 3 -- says the batteries are at the end of automotive life when their capacity falls to 80 percent, or when the cells undergo a 30 percent increase in resistance. A rise in cell resistance impedes power distribution to the motor, Clark said.

The Leaf and Volt have 8-year/-100,000-mile warranties.

The consortium aims to develop electrochemical storage technologies to support the commercialization of electrified vehicles. Clark said the consortium works closely with the U.S. Department of Energy, suppliers and developers of energy storage.

Batteries from opposing automakers cannot be combined in a storage system because of differing characteristics.

"Batteries that are going into the Volt, for example, are different than the ones going into the Leaf. They are different than what's going into the Tesla," Portland General Electric's Allcock said.

"Batteries have all kinds of characteristics. You can't mix and match on battery packs from different vendors. It just doesn't work that way."

When combining multiple compatible batteries in one storage unit, GM's Valencia said, it's important to have a control system that ensures the batteries work in unison.

He said GM engineers in Oshawa, Ontario, and Warren, Mich., who design EV battery systems are working on the software and algorithms to make that happen. Those engineers also are exploring secondary uses, Valencia said.

"One of those key pieces is the controls and the ability to charge the batteries up evenly at cell level, at a section level and an overall system level. Keeping all that balance in place is really the secret sauce to making any battery system work whether it's a new battery system or a secondary-use battery system," Valencia said.

"The bigger the system is, the more important it is to keep it playing like a good orchestra with all of the pieces in balance with each other."