GM-VOLT : Chevy Volt Electric Car Site

One of the problems inherent in electric cars is the fact that their batteries degrade. Lithium-ion cells work best when they are new, but over time their ability to hold a charge continually lessens. GM estimates the Volt battery will degrade by 10 to 30% after 8 years/100,000 miles. The company has worked hard to develop methods keep the cells as healthy as possible, and minimize degradation. These methods include keeping the temperature of cells in the ideal (roughly room temperature) range, and not permitting full charges and depletion.

Nonetheless, loss of function is inevitable, and batteries will eventually need to be replaced.

To maximize the potentiating for used cells, GM apparently has significant internal plans to refurbish used cells, as evidenced by a patent application submitted last year.

In the patent application called METHOD AND APPARATUS FOR REJUVENATION OF DEGRADED POUCH-TYPE LITHIUM ION BATTERY CELLS, the automaker spells out a system that would take used lithium-ion pouch cells and restore their function.

It is explained that at cells age, the electrolyte material in them breaks down and leads to the deposit of lithium salts and other polymeric materials on the surfaces of both the positive and negative electrodes. As well, magnesium may be deposited on the negative electrodes. It is believed that both these deposits as well as breakdown of the electrolyte solution itself causes the cells to lose power over time.

In the invention, old cells would be hooked up to a manifold and a specialized solvent would be pumped in under pressure and then heated for up to one hour. A series of potential solvents or mixtures thereof is given.

This treatment is expected to remove the contaminants from the surface of the electrodes, and allow infusion of fresh electrolyte. It is suggested that such treatment may restore the cells to their original level of function.

Much of the patent describes the various ways the tubing and pumping could be designed to fit variety of cells and work under variety of conditions.

The patent concludes that rejuvenation of cells would be much less expensive than manufacturing new ones. One vision describes vehicle owners waiting at a facility while their car battery is rejuvenated on-site. Another vision describes replacing an owner’s battery with a new one, and then rejuvenating the old one for secondary use.

You can read the whole patent here.

The battery pack for the Chevrolet Volt is warrantied for 8 years/100,000 miles. GM considers this the best available warranty for a new technology battery of its kind. It does not meet the California Air Resources Board (CARB) requirement; however, necessary for them to consider the car as a partial-zero emissions vehicle. That standard is 10 years/150,000 miles.

As such, CARB designated the Volt as ULEV, similar to a fuel efficient gas car, not considering its EV operation.

GM expects the 2012 model year Volt to meet the CARB requirement, though the New York Times reported Volt director Tony Posawatz as saying GM needed to work out some “kinks” before they could increase the warranty.

I asked Mr. Posawatz exactly what those kinks might be.

“Nothing out of the ordinary,” he said. “We are leading with the 50 state version with an 8 year warranty before we start the version for CA that requires 10 years.”

“It’s just smart business,” he added.

Pressed further as to whether technological refinements had to be implemented he said, “just continuous improvement which customers would expect of us.”

Another attribute lacking in the 2011 Volt is E85 capability. Engineers previously said the 2012 car will have it. Or will it?

According to Posawtz, E85 “timing (is) being determined.”

At the recent Chevrolet Volt launch GM finally let the skeletons out of the closets and exposed all of the Volt’s closely guarded secrets. Among them is the fact that engineers have chosen to use much more of the battery’s stored energy than initially beleived.

We had believed for years based on GM statements, that the car would only draw a total of 8 kwh of energy from the 16 kwh battery pack to deliver the 40 miles of EV range. The idea was considerable excess buffer existed in the pack to let it deteriorate over time without sacrificing range.

Through the years of development GM became more comfortable with drawing more deeply from the pack, finding the properly-conditioned cells could handle it. Even with a deeper band of energy use, GM felt it could meet the warranty goal of 8 years/100,000 miles. Also, though executives and engineers won’t overtly admit it, it seems they needed more energy than initially believed to the acheive the goal EV range.

This first came out when we recently learned the Volt would use more than 8 kwh.

Now GM finally admits the Volt will actually use 65% of the total energy storage capacity of the battery. That amounts to 10.4 kwh.

The engine generator will turn on once the battery hits somewhere between 20% and 25% state of charge, which equates to 25 to 50 miles of EV driving. When fully recharged, the battery will acutally be kept at a maximum 85% to 90% state of charge.

As the battery ages and energy storage capacity of the lithium-ion cells degrades, control units will widen the percent state of charge band to continue to deliver the range goal.

By 8 years/100,000 mile when the battery warranty ends, GM expects the car’s range to be reduced by 10 to 30 percent in the worst case. Some customers will experience less degradation. The car can continue to drive beyond that point, but range will continue to contract.

It was recently reported that the California Air Resources Board (CARB) classified the Volt as a ultra-low emissions vehicle or ULEV. This is the same as a 1.8L Honda Civic, for example. Less carbon emitting and more stringent designations include (super) SULEV, and advanced technology partial zero emission vehicle (AT-PZEV) given to the Prius and Insight. The most stringent is the zero-emission (ZEV) designation given to pure electric cars.

The ULEV designation does not, however, take into account the Volt’s electric driving operation, it only looks at the charge sustaining mode operation. GM will seek a new (enhanced) EAT-PZEV status next model year, by offering the required 10 year/150,000 mile warranty that CARB wants to consider electric operation. To achieve that warranty, apparently “certain kinks” have to be worked out Volt director Tony Posawatz told the Times.

There are several pieces of information about the Chevy Volt that have been accepted as immutable fact since early on in the car’s transparent developmental process.  One of those has to do with the amount of usable energy that will be drawn from the battery to drive the car.


We have always been told the Volt would use 8 kwh to drive 40 miles, and thus about 50% of the battery’s total capacity, operating within the roughly 30 to 80 percent state of charge band. This number also indicated the vehicle’s efficiency is roughly 5 miles per kwh


At the Consumer Advisory Board information conference, Volt vehicle line director Tony Posawatz issued an addendum of sorts.  The Volt will use “a little bit more” than 8 kwh.  He would not be specific about how much more, instead assuring us we “will found out” when we start driving the car.


Britta Gross who is GM’s director of infrastructure indicated how much electricity consumers should expect to draw from the grid in order to fully recharge a depleted battery. “Assume an upper bound of 10kWh needed to fully charge the battery (from empty),” said said. This would include grid energy also used to condition the battery.


The Volt will issue monthly statements describing how much energy the car has consumed which will be sent to email via OnStar and be accessible on myvolt.com.


Over time as the battery degrades the car’s electric range will gradually decline.  The pack should reach about 70 to 75% of capacity after 8 years/100,000 miles.  The car will gradually increase the usable state of charge band, however, to continue enabling the 25 to 50 miles of electric range.


The car can continue to be driven long beyond that 8 year/100,000 mile point, and in secondary applications the battery could be used for an equal number of years.  Eventually consumers will see electric range degrade, though the generator will always be there to allow normal usage.


If you’re feeling a little adventurous you can also discuss this post in our new and improved GM-Volt Forum.

General Motors has signed a memorandum of understanding with the ABB Group to explore opportunities for the reuse of Chevrolet Volt batteries packs after their vehicular lifetimes have ended.

The Chevrolet Volt’s 16 kwh lithium-ion battery pack has a warranty of 8 years/100,000 miles during which time 40 miles of EV driving range can be maintained.  This is the longest most comprehensive warranty of it’s kind in the automotive industry and is fully transferable between owners. The warranty includes all 161 part of the battery, 95% of which were designed and engineered by GM. It also includes the thermal management, charging system, and electric drive components

It is known that the Volt’s battery will still have very significant energy storage capacity after the warranty period has ended.  The new partnership with ABB is looking at ways to best  utilize that energy storage capacity. “The Volt’s battery will have significant capacity to store electrical energy, even after its automotive life,” said Micky Bly, GM Executive Director of Electrical Systems, Hybrids, Electric Vehicles and Batteries. “That’s why we’re joining forces with ABB to find ways to enable the Volt batteries to provide environmental benefits that stretch far beyond the highway.”

ABB is the world’s largest supplier of power grid systems and a leading power and automation technology provider. Their technologies allow utilities and industry to improve performance, while at the same time reducing their environmental impact. “Our relationship with ABB will help develop solutions that optimize the full lifecycle of the Volt battery,” said Bly.

“Future smart grids will incorporate a larger proportion of renewable energy sources and will need to supply a vast e-mobility infrastructure – both of which require a wide range of energy storage solutions,” said Bazmi Husain, head of ABB’s smart grids initiative. “We are excited to explore the possibility of employing electric car batteries in a second use that could help build needed storage capacity and provide far-reaching economic and environmental benefits.”

The joint venture will explore the utilization of used Volt packs in the following ways:

• Renewable Energy Storage: Power generated by wind and the sun can be stored in Volt battery systems and used when demand warrants.
• Grid Load Management: Utilities will be able to use the Volt batteries to store electricity generated during off-peak periods to supplement demand during high-peak operation. This will help utilities to better manage the grid, improving reliability and efficiency.
• Back-up Power Supplies for Communities: Volt battery systems can store electricity that can be used by communities during power outages caused by storms or other natural disasters.
• Time of Use Management: Industrial customers can store off-peak, lower-priced electrical power in Volt batteries for use during peak demand time of day for cost savings.

“Chevrolet and GM are committed to assuring that our vehicles minimize their impact on the environment,” Bly said. “Our focus on finding additional applications for the Volt’s batteries after their vehicle use extends our commitment to unprecedented levels.”

Source (GM)

After all this time its pretty amazing to hear GM’s final decision on the Chevrolet Volt’s battery warranty.  Eight years or 100,000 miles.

We have known for a long time that GM was aiming towards ten years/100,000 miles as a goalpost, though using that figure specifically as a warranty was never confirmed.

This warranty is being described as the longest-lasting GM offers on any of its products, illustrating the very high level of confidence the company has in its extensively engineered and managed lithium-ion battery pack.  It exceeds by three years the warranty GM offers on its powertrains.

The warranty coverage includes all 161 components of the Volt’s battery, its charging system, thermal-management system and components of its electric drive, and it is transferable to other vehicle owners. GM confirmed that the 400 pound pack houses 288 cells in nine modules.

Volt vehicle line executive Doug Parks GM provided some additional details about the warranty.

First the warranty is good at delivery, no minimum number of miles are required, and the mileage is calculated in terms of vehicle miles, not generator miles.

It was long thought GM must achieve a ten year warranty specifically for California and the other CARB states. This turns out not to be the case.

The “warranty announcement covers all states, including California,” said Parks.  ”California does not mandate 10 years/150,000 miles for all vehicles.”

The reason, as it turns out, is that GM did not submit the Volt as an advanced technology partial zero emission vehicle to CARB (California Air Resources Board). Therefore, GM is not required to meet those warranty criteria. It also means California Volt buyers will not get the $5000 tax credit. GM expects to achieve AT-PZEV designation in the 2013 model.

“The Volt’s battery warranty announced this week is based on the remarkable results of our engineering and development testing,” GM spokesperson Shad Balch told GM-Volt. “When we complete the additional engineering and submit the vehicle to CARB for AT-PZEV certification it will include the required 10/150K battery warranty.”

“We expect to do this with the 2013 MY, which will be available mid-2012,” he added. “AT PZEV for 2011 MY would have required additional costs and delayed the launch. We could have pushed back the launch – but customers want a practical EV now.”

“California’s rebate program has funds to cover fewer than 700 customers, total, for vehicles from all manufacturers – and future funding is uncertain,” he added. “Rather than sticking it to thousands of our customers with a delay, we chose to remain on track and launch the Volt this year.”

GM is continuing to look at battery performance beyond the ten years as well. “The batteries are being validated beyond the warranty period,” said Parks. “We continue to test to see how far they will live.”

Parks also noted that the battery is warrantied for both level 1 (120-v) and level 2 (240-v) charging, and that the use of either has no effect on performance or longevity. He said that if a pack wound up needing repair some work could be done at local dealerships. “However all refurbishment/cell replacement will be done at a central specialized repair center,” he added.

Parks noted the warranty will cover “all customer charge cycles,” even if owners charge the car multiple times per day.

Overall GM noted that its battery warranty was significantly longer that what Tesla offers on its Roadster which is “3-year, 36,000-mile standard,” according to Tesla spokesperson Rachel Konrad. “You can buy a two-year extension,” she added. Tesla also offers owners the option of paying a non-refundable $12,000 to get a free battery replacement at seven years..

And for what seems like the first time, GM beat Nissan to announcing something about its electric car.

According to Nissan North American Director of EVs, Mark Perry, Nissan has “no comments yet,” on the air-cooled LEAF battery warranty. “We will release a bit closer to launch,” he added. Nissan has surveyed its $99 reserve holders about their battery warranty expectations, and may be aiming for 5 years/60,000 miles. The LEAF, as a zero-emission vehicle (ZEV) will be eligible for the $5000 California credit for those who can get it.

“No battery warranty requirement/regulations from CARB for ZEV,” says Perry. “Nothing for the air resources board to regulate.”