In this episode - EV Batteries . . .
I've been reading a lot lately about battery storage and the electric power grid. We thought you might find the following article from MYEV.com helpful, especially if you own an Electric Car (EV) or a Hybrid.
However, one area of concern that keeps coming up in consumer surveys is an electric car's battery life.
In a recent study conducted by Cox Automotive, 46 percent of those considering an electric vehicle fear the battery pack would only last for 65,000 miles or less. To be sure, replacing an electric vehicle's battery is an expensive proposition. According to MYEV.com, a new battery pack for a Chevrolet Bolt EV is reportedly priced at $15,000+, not including the labor cost.
While an electric car's battery pack will eventually lose its ability to hold a full charge, it's not likely to fail altogether but gradually lose its capacity. Nissan reports swapping out only a relative handful of batteries in its Leaf EV, despite selling thousands of units over the last eight years.
BATTERY BASICS
The lithium-ion battery packs used in electric cars are similar to those used in cell phones and laptops, only bigger. They're very different from the heavy lead-acid batteries used in conventional vehicles and have a higher energy density than rechargeable nickel-metal hydride batteries. They're also less prone to lose their charge when not being used than other battery types. EV battery packs generally contain a series of connected individual cells, perhaps several hundred depending on the model, instead of one massive unit.
An electric car's battery capacity is expressed in kilowatt-hours, abbreviated kWh. Choosing an EV with a higher kWh rating is like buying a vehicle that comes with a larger gas tank in that you'll be able to drive for more miles before you need to "fill up."
Keep in mind that an electric car's management system prevents the battery from becoming 100 percent fully charged or 100 percent discharged to preserve it. The Environmental Protection Agency rates electric vehicles according to their energy efficiency and estimates each model's average operating range on a full charge.
However, as they say, "your mileage may vary." If you own an electric car and find that you're not getting anywhere near the estimated range, that doesn't necessarily mean the car's battery pack is becoming seriously depleted.
Driving at higher sustained speeds will use more battery power than stop-and-go around town use, for starters. For many people, that's counter-intuitive as it's the opposite of how a gas-engine car works, which uses less fuel while cruising at highway speeds than in traffic. Also, it takes more power to propel an EV with a full load of passengers and cargo than a car with only the driver.
Notably, extreme temperatures, especially bitter cold, can hamper both a battery's performance and ability to accept a charge. Using the heater or air conditioning also draws battery power more significantly than average. A study conducted by AAA found that when the ambient temperature dips to or below 20°F and the vehicle's heater are in use, the average electric car's operating range drops by 41 percent. When the temperature hits 95°F and air conditioning is in use, an owner can expect the range to fall by 17 percent.
BATTERY LIFE
Though some electric car buyers take out extended warranties to save any fears of excess battery depletion, it's unnecessary. At that, the batteries in all-electric cars sold in the U.S. are covered under warranty for at least eight years or 100,000 miles. Kia covers the battery packs in its electric vehicles for ten years/100,000 miles, while Hyundai goes further by bumping it up to lifetime coverage.
Be aware, however, that some automakers only cover the battery pack against a complete loss of its ability to hold a charge, which would be extremely rare. Others, including BMW, Chevrolet, Nissan, Tesla (Model 3), and Volkswagen, will replace the pack if it falls to a specified capacity percentage while under warranty, usually 60-70 percent.
But how long would it be before an electric car loses its ability to hold a full charge? While an electric vehicle's battery pack will degrade slightly with each charge and discharge cycle, it's an extremely gradual process. For example, according to data compiled by the organization Plug In America, the battery pack in a Tesla Model S will only lose around five percent of its original capacity over the first 50,000 miles, with the rate of depletion slowing down.
In a recent Tesla discussion thread on Reddit, most of those owning a Model S reported losing only a few percentage points of the car's initial battery capacity after several years of use.
On the downside, electric cars in the hottest climates can lose battery capacity quicker than those in more temperate areas. Extreme heat is the enemy of lithium-ion chemistry, so many electric vehicles have liquid-cooled battery packs. Also, older electric cars having relatively short operating ranges may suffer quicker deterioration. Regularly draining most of a battery's charge tends to cut into its capacity more quickly. That's far less of an issue with today's longer-range models typically driven for a fraction of their available capacity daily and are merely "topped off" at night.
Excessive use of public Level 3 DC Fast Charging stations (designed to bring an EV up to 80 percent of its capacity in 30 minutes) can also affect a battery's long-term performance. The faster an electric car is charged, the hotter it becomes, and that's not battery friendly.
However, a study conducted by the Idaho National Laboratory concluded that the effect isn't particularly pronounced. The INL tested two pairs of identical 2012 Nissan Leaf models, with one set using 240-volt Level 2 home charging and the other exclusively relying on DC Fast Charging public units. After each was driven 50,000 miles, the difference between the Level 2 and Level 3 vehicles' diminished battery capacities amounted to just four percent.
The bottom line is that if it's properly cared for, an electric car's battery pack should last for well more than 100,000 miles before its range becomes restricted. Consumer Reports estimates the average EV battery pack's lifespan to be around 200,000 miles, nearly 17 years of use if driven 12,000 miles per year.
Tesla claims it's working on technology that would enable its electric car batteries to last for as many as one million miles, likely more than the rest of the car. Now that's a lifetime-of-the-vehicle component.
I'm Patrick Ball; thanks for listening. I'll see you in the next episode.
Comments