How Long Should an EV Battery Last?
There’s one thing all rechargeable smartwatches, smartphones, tablets, and laptops have in common: battery life. It almost feels as if manufacturers make them only to last about 3 years, coinciding with the same time the latest must-have device is released. Many think of electric vehicle batteries in the same light and assume there is the same type of short lifespan, which couldn’t be further from reality. Fortunately, automakers are not building electric vehicles like smartphones. Modern EV batteries are in it for the long haul these days, with some electric vehicle batteries guaranteed to deliver a promised range of up to 10 years or 150,000 miles. The latest battery technology is pushing 300,000 miles in laboratory testing. That’s over 20 years of (generally) emissions-free driving. There are several reasons modern EV batteries last so long.
Battery technology is improving all the time, and Lithium-ion (Li-ion) and Lithium-Iron-Phosphate (LiFePO4) EV batteries last much longer than earlier types. Manufacturers have learned how to better manage battery charging and discharging, also called cycling. Today’s battery management systems (BMS) keep EV batteries at the best state of health (SoH) far longer than the old NiCad and NiMH (nickel-cadmium and nickel-metal-hydride) batteries.
Tesla, the current leader in EV battery and electric vehicle technology, reports typical SoH losses at just 5% at 50,000 miles. When it comes to EV battery lifespan, you’ve got little to worry about although there are still a few things you can do to maximize it.
How to Increase EV Battery Life
There are several factors that determine the lifespan of a rechargeable battery. Physical age, total cycles, charge rate, load rate, and temperature all play a part. Today’s BMS engineers use everything they’ve learned in the last decade to maximize the life of your EV battery and most EV warranties will replace a bad battery at little or no cost to the EV owner. You have almost no control over any of this, of course, but it’s good to know what’s going on under the EV hood, so to speak. Battery SoH and temperature are the biggest factors determining charge rate; that is, how many kilowatt-hours (kWh) you can force into it per minute. Chargers are rated at maximum power output in kilowatts (kW). Home charging stations typically deliver 3.5 kW to 7 kW, but some go as high as 22 kW, and grid-level L2 and L3 battery chargers usually deliver 50 kW to 150 kW, but none of these chargers indiscriminately force the max charge to your EV battery. Instead, the charger communicates with the vehicle BMS to regulate charge rate to maximize battery lifespan and stop undesirable side effects like explosions. On a scorching hot day, a 150 kW L3 charger might lower to 90 kW or, on a freezing day, a 22 kW home charger might throttle to 18 kW. Charging takes a little longer, but the battery will last longer. As an EV driver, there are two things you can do to maximize battery lifespan. First, stick with home charging and L2 charging when possible. Of course, you can always use L3 charging stations, sometimes called Superchargers, but it’s best to do this only occasionally to maximize your EV battery’s life. Second, knowing that most SoH damage occurs below 32 °F and over 120 °F, be sure your EV battery’s warming or cooling system is working properly and limit charging on extreme temperature days.
Can I Charge my EV to 100%?
The technical answer is “No, you should never charge your EV battery to 100%,” but in practice, you can go right ahead and do it without impacting battery life. The BMS keeps things under control, so you don’t have to think about these kinds of questions. Instead, the BMS displays percent of usable charge. Say you start with a new electric vehicle with an advertised 100 kWh battery capacity and 300 miles range. Your actual physical battery capacity is more like 300 kWh. “Whoa, does that mean I can get 900 miles out of this puppy?” Sure, you could charge to 100% of 300 kWh and ignore the charger for 3 weeks, but you wouldn’t be able to do that too many times before the battery calls it quits. That’s why the typical smartphone lasts only a few years, by the way. It can go just a few hundred battery cycles because you have access to the entire battery capacity. Batteries for electric vehicles work differently, though. When new, the BMS only lets you use 30% to 80% of the vehicle battery’s physical capacity, delivering the promised 300-mile range. Hundreds of cycles down the road, the BMS continues to deliver 300 miles, gradually consuming the upper and lower buffers. A few hundred cycles later, the BMS lets you use between 10 and 90 percent of the battery’s available capacity, maybe 150 kWh, but you’ll still get around 300 mile range when driving. Closer to the end of the battery’s life, you’ll see a drop in range when the BMS no longer has any buffer.
What Happens to EV Batteries at End of Life?
So, here you are, 20 years and 300,000 miles later and your 300-mile EV battery is only delivering 100 miles. Before you dump that electric vehicle or replace the battery, consider how much range you really need. Maybe a short-range EV is perfect for a second vehicle or as a trainer when your teen is learning to drive, but that’s not the only option for a spent EV battery. Today, spent EV batteries are already living second lives as backup power storage for renewable energy generation. At home, off-grid, or grid-level, used EV batteries are keeping power generation and power delivery smooth when the weather is off, reducing our dependence on fossil fuels. It’s a win-win. Once your EV battery’s components are well and truly dead, maybe another 10 years down the road after use in a second life, it’s time for recycling. Currently, about 50 percent of the typical battery is recyclable. Eventually, new processes are expected that could push upwards of 90 percent EV battery recycling, minimizing as much environmental impact as possible.
