4 Tips to Avoid the EV Battery Issues That Icy Chicago Just Had
Recent reports of stranded Tesla drivers in snowy Chicago shows us that owning an EV comes with its disadvantages. But experts say there are ways to prepare for extreme cold (and hot) weather before you drive.
Sam Becker is a freelance writer whose work has appeared in and on CNBC, Fortune, USA Today, Business Insider, and more. Sam is also the author of the growing finance and strategy-focused newsletter, "Not Pretty, Not Rich."
The adoption of EVs is expected to accelerate in the coming years, but negative news reports of EVs failing in extreme weather may scare off EV fence-sitters. Before you put your EV-purchasing plans on ice, experts say the most important thing that EV owners can and should do is know why extreme temperatures affect their car differently than gas-powered vehicles, and how to mitigate the effects.
"For people thinking about going to EV, just get educated," says Rick Wilmer, CEO of ChargePoint, which operates the world's largest network of EV charging stations in North America and Europe. "If you understand how it works on a basic level, you should be fine."
The primary difference between an EV and a vehicle powered by an internal combustion engine is that EVs are powered by batteries. And batteries can get absolutely walloped by the cold.
"The colder it gets, the more you're going to see an impact," says Alex Knizek, manager of auto testing and insights at Consumer Reports. Knizek says that the cold can disrupt or slow "the chemistry happening in the lithium-ion batteries -- when it gets colder, there's more resistance, and it's more difficult for the chemical reaction to take place."
Knizek adds that "not only is that happening in the battery, but a lot of EVs have a heating system to get the battery up to its preferred operating temperature, so the battery warms itself up." That process, too, can be stymied by cold weather. Add in that drivers are likely cranking the heat to warm themselves up in the cabin, further taxing the battery, and it can slow things down even further.
Studies have shown that in most cases lithium-ion batteries tend to see the biggest degradation in performance at or below freezing temperatures -- 32 degrees Fahrenheit, or 0 degrees Celsius. That may be the "magic number" of sorts for EV owners to look out for.
As Knizek explains, the cold-weather performance issues experienced by many EV owners really boil down to slower chemical reactions in the vehicles' batteries. And, for the most part, EV owners are experiencing two main issues related to performance in extreme weather: their overall range is reduced, and it can take a lot longer for batteries to recharge.
As noted, cold weather can reduce an EV's range -- accordingly, EV drivers should expect relatively lackluster performance if it's particularly cold outside (or hot -- see below). But it's difficult to say just how much of a reduction in performance EV owners should expect, as it'll depend on the specific make and model of the EV, and the conditions themselves.
Knizek notes that gas-powered vehicles also see their performance suffer a bit due to colder temperatures, but "the impact isn't as drastic or noticeable." He adds that for EV owners, the specific car, conditions and accessories being used in the car (such as the heater) "can combine to chip away at performance" and overall range.
Longer charging times
Longer charging times are the other chief issue EV owners encounter in the cold. While much of the issue relates to a battery in an EV itself being cold, and needing to warm up first to charge efficiently, the chargers themselves may be cold and increase charging times.
The problems are mostly "related to the EV and the battery itself," says Wilmer. But "the other half of the equation is the charger itself -- the charger needs to work in cold weather," he says.
Charger performance will vary, but Wilmer says that ChargePoint chargers are tested in very cold temperatures -- down to -40 F (which is also -40 C). During recent winter storms in Chicago, he says the company was "watching our network and didn't see any real anomalies in terms of charger performance -- sessions took maybe 5% longer, which isn't unusual even during milder weather."
EV care tips in cold weather
While EV owners can't control the weather, there are a few things they can do to try and get ahead of it, and keep their EVs performing at the highest possible level.
Charge at home, and park inside (if possible)
While it may go without saying, charging your car at home and parking it indoors is the best way to get a jump on the cold weather. That way, an EV is insulated from snow and ice, and should be ready to go with a fully charged battery -- as long as you have a garage, and the equipment to charge at home. "If you can charge at home, charge at home," says Wilmer.
Knizek recommends EV owners "pre-condition" their vehicles before use -- which essentially means heating them up before hitting the road, while they're still attached to a charger. "Remote-start your EV while connected to the charger," he says. "Heat the car up, and the battery up while it's still connected, and it'll use energy from the charger, not the battery."
CNET's resident EV expert, Antuan Goodwin, also points out that many EVs use their navigation system to help prepare their battery for the fastest charging. If you include a DC fast-charging station as a GPS destination, the car will know that it's about to get a charge and do a quick battery warm-up pre-condition just before you arrive for faster charging. If you don't use GPS, the software doesn't know to do this and arrives at the charger cold, which can add to charging duration. This sort of on-the-go pre-conditioning costs a little range since you're using the battery to warm the battery, but because it only happens just as you approach the charger, the tradeoff is small and worth the time saved waiting.
Since using the heater inside the car also uses battery power in an EV, Knizek says if you can set the heat to a lower setting, you may see a slight benefit in increased range. "If you can get away with 70 as opposed to 75," he says, "you'll see a range benefit."
Try to keep the battery above 20%
Wilmer says that EV drivers should also do their best not to let their battery life fall below 20%. The 80/20 rule, relating to batteries, says that batteries tend to be more efficient operating at between 80% and 20%, and that also applies to EV batteries. But Wilmer says that finding a charger before your battery dips below 20% is best practice -- in terms of efficiency, and winter safety.
You wouldn't want to be stuck in a gas-powered car in the winter with the fuel gauge hovering near "E," either.
While EVs have problems in the cold, it's definitely worth asking: Do they have performance problems when it's hot outside?
While EV owners in Fargo, North Dakota, will have issues in the winter, the same isn't necessarily true for EV owners in Phoenix during the summer, because temperature-related performance issues are a cold-weather problem. "Most people are going to experience [problems] in the cold," says Knizek. But there could be some loss of battery efficiency, he says because in extreme heat, the "battery needs to cool itself down."
As such, there can be a loss of range and performance in extreme heat, especially if drivers are revving up the air conditioning to cool down the cabin, which also requires battery power. In the past, that could affect an EV's range by as much as 20%. But technology is improving, and different cooling tech, such as heat pumps, has helped keep ranges up.