Mikael G. Cugnet, Ph.D. spoke on the question that worries millions of owners and potential owners of electric and hybrid vehicles (EVs) using lithium-ion batteries: How long before the battery pack dies?
A view to the answer was presented at the 245th National Meeting & Exposition of the American Chemical Society (ACS), may surprise skeptics. One hopes so, a dead battery pack would present a super sticker-shock bill for a fresh pack or force a car to be ready for the junk heap. It’s a serious matter.
An EnerDel battery Pack as Used in the Chevy Volt.
Cugnet said, “The battery pack could be used during a quite reasonable period of time ranging from 5 to 20 years depending on many factors. That’s good news when you consider that some estimates put the average life expectancy of a new car at about eight years.”
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Cugnet explained that the lifespan depends mainly on the battery’s temperature, state of charge and charge protocol. Battery performance begins to suffer as soon as the temperature climbs above 86º Fahrenheit. “The higher the temperature, the lower the battery service life,” he said. “A temperature above 86º F affects the battery packs performance instantly and even permanently if it lasts many months like in Middle East countries.”
Cugnet also recommended that electric vehicle owners pay attention to how much their battery is charged, another factor in a battery’s longevity. He reported that a fully charged battery is more vulnerable to losing power at temperatures above 86º F.
To test the limits of lithium-ion EV batteries, Cugnet’s team reconstructed the experience of a typical EV battery in the laboratory. Using data gleaned from a real five-mile trip in an EV, they put EV battery packs and cells through simulated lifetimes of driving with cycles of draining and recharging. The researchers considered a battery to be beyond its useful lifespan when it had lost 20% of its full power.
The question of longevity matters to EV owners and manufacturers alike. The cost of the lithium-ion batteries that power these vehicles remains high, and an EV can cost twice as much as a gas or diesel equivalent. Customers want to make sure they get their money’s worth, and manufacturers are eager to demonstrate that EVs are economical.
One obvious saving is the cost of fuel over a car’s lifetime, but EV makers are also pushing so-called “second life” uses for batteries that could make them valuable even after they’ve lost too much power to be useful in cars. These applications could include backup power for computers and medical equipment, or electrical grid storage, which would go hand-in-hand with renewable power like wind or solar to keep electricity flowing even when environmental conditions aren’t right. Another option is recycling a battery’s components to make new batteries
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The ACS press release isn’t specific on what Lithium-ion technology was used in for the testing. For those using cell phones past the usual two year contract the experience isn’t encouraging. Nor are the test conditions made clear for a direct consumer comparison to real working experience with a current vehicle.
Technology is marching forward on battery technology and will solve the concerns over time and likely offer a much better and useful “second life” that may hold a much better residual value. But whether the values are estimated at 8 years or 20, the range is a huge period in battery technological development. In a decade it would be fair to expect the technology would be fully obsolete.
What Cugnet offers in real terms now is – don’t let that battery get warmed up past 86º F for any extended length of time.
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The most interesting thing will be how the advice and knowledge changes as the technology improves.
By. Brian Westenhaus
Original source: How Long Will My Battery Last?
Only 10.8 kW·h of the battery's 16.5 kW·h capacity is charged and used. The remainder is a buffer that prevents full charge or full discharge of the battery—both known to shorten battery life.
This is why GM is able to warrant the battery for 10 years. Tests indicate 16-20 lifespans may be expected since the battery is carefully protected from the negative affects of heat and state of charge.
-BatteryWarehouseDirect.com