Electric Car Battery

You Only Live Once, unless you are an EV battery


The expression that enjoyed a brief but spectacular reign as the motto for our nation’s youth does not apply to the batteries of electric vehicles. Once the range of your EV falls to an unacceptable level, that battery will not simply get thrown away.

Even the most passionate electric vehicle advocates will reluctantly agree that lithium-ion batteries have a limited life span. Just how long that life will be is a subject of great debate and importance, and the jury is still out. Look for an article on the subject here at Torque News in the near future, but for now assume that a typical EV battery will last for 10 years or so.

When the capacity falls below 80% of its initial value, your Nissan LEAF is only achieving 50 or 60 miles of range and you decide the vehicle no longer fulfills its purpose, what happens to the battery? Assuming you bought your vehicle in 2010 or later and your battery lasted a decade, the year will be at least 2020 and one of two things will happen.

Option 1, the less desirable of the two, is that the battery will be sent straight to a recycling facility. There, the battery will be shredded and the metals such as cobalt, aluminum, nickel, and copper will be recovered. The lithium salts will be filtered out and converted to lithium carbonate, though the economic value of the lithium itself is minimal compared to metals like nickel and cobalt.

Lithium-ion batteries are less conducive to recycling than the previous generation of nickel-metal hydride cells that are far richer in valuable nickel, and the economic benefit of recycling varies based on the battery chemistry. However, on a large scale the economics of battery recycling do make sense. And though it will not be the only such facility in existence by 2020, a company called Toxco received D.O.E. funding to build a dedicated EV lithium-ion battery recycling facility in Ohio. The plant is due to be completed in late 2014 or early 2015.

Option 2, however, is where it gets interesting. A Nissan LEAF battery with 80% of its capacity remaining still can hold about 19 kWh; the larger Tesla Model S battery will be capable of storing a whopping 68 kWh (although if I own a Model S and my battery degrades to 80% of the initial capacity, I’m still okay with 212 miles of range). It would be a great waste if battery packs with such great energy storage potential were consigned to the shredder.

That’s where the so-called “second life” of EV batteries comes into the picture. Automakers, research labs, think tanks, universities, and companies all over the United States and the world have dedicated significant resources to investigating secondary uses for spent electric vehicle batteries.

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Comments

Another thing to consider is improved battery technology and falling prices. I'm sure many Leaf owners would swap out their batteries much sooner than 2020 if a new battery in the same space could provide more range for a reasonable price. Let's say in five years the power density is increased by 30% and the cost is down to $125 per kWhr. A 38 kWhr pack would travel 125 miles instead of the by then degraded 85 miles and cost about $5000. The residual value might be $90 per kWhr for home use, or about $2000, so the upgrade would have a net cost of $3000. If in 5 years solar is down to $1 watt installed, then 6 KW of panels should be enough for most people, so going off grid allowing for $2000 worth of used car battery would cost about $8000. 1200 W ave at 8 cent per kWhr is 10 cents per hour, 2.40 per day, $75 per month, $900 per year, $8100 per 9 years. Since such a system would last at least twice as long, maybe three times as long, so the cost of power would be about 4 cents per kWhr, allowing for occasional upgrading of the battery and panel capacities.

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