On Monday, the Canadian Automobile Association — think AAA but with maple syrup — published the results of its recent round of cold weather EV testing. The premise was fairly simple: Take 13 EVs, put them in temperatures ranging from around 20 degrees Fahrenheit to five degrees Fahrenheit, then test both their DC fast charging capabilities and real world range when temperatures get frosty. While we’ve seen plenty of cold weather range tests before, a cold weather charging test is novel, especially considering the use of portable DC fast charging equipment from the same company for each car.
As far as cold weather DC fast charging went, American EVs performed fairly well in this test. The Chevrolet Silverado EV was a dominant force, averaging 233 kW, but the Ford F-150 Lightning, Chevrolet Equinox EV, and Tesla Model 3 all performed reasonably well, averaging 128 kW, 100 kW, and 96 kW during testing. On the other hand, the Ford Mustang Mach-E with the long-range battery pack brought up the rear for America by averaging 85 kW or 56.6 percent of its peak rating of 150 kW.
European electric vehicles also performed fairly well in this test, with the Volkswagen ID.4 Pro averaging 104 kW, or 61.2 percent of its peak rating. The Polestar 2 and Volvo XC40 Recharge diverged on average charging kW despite sharing an architecture, with the former averaging 94 kW and the latter averaging 87 kW.
In contrast, a bunch of Korean EVs, notably the Hyundai Ioniq 5, Kia Niro Electric, and Kia EV6, floundered pretty hard in average DC fast charging speed. The Ioniq 5 averaged 80 kW in this test, the EV6 85 kW, and the Niro just 36 kW. Is this just a case of the chargers not being optimized for Hyundai and Kia’s 800-volt architecture? Not quite. See, the Niro EV runs a 400-volt architecture, and the Kia EV9, another E-GMP car with an 800-volt architecture, managed to pull an average of 136 kW. Considering the Ioniq 5 and EV6 are both capable of charging peaks north of 220 kW, and that CTV News reports that all vehicles in the test save for the Tesla Model 3 were hooked up to 350 kW chargers, these results certainly raise a few eyebrows.
However, the big losers of the cold weather DC fast charging test were the Toyota bZ4X and the Honda Prologue, albeit for very different reasons. As CAA put it, the “Honda Prologue was not included in the charge test as it encountered an error and data was unavailable.” Oh dear. On the other hand, the Toyota bZ4X averaged a measly 33 kW in this test, which isn’t particularly fast at all. CAA found it added just 11.8 miles of range in 15 minutes, and required 92 minutes to charge from 10 to 80 percent in winter conditions.
So how do these figures compare to those seen in other conditions? Well, it’s time to give a shoutout to Out Of Spec Studios, because they’ve consistently been testing DC fast charging curves for years, and their data offers up some excellent points of contrast. While we are talking about different equipment and different conditions here, the weather outside isn’t the same all year round, and contrasting these two data sets shows just how much DC fast charging performance can change depending on external factors.
Take the Hyundai Ioniq 5 for example. In Out Of Spec’s testing, it started at 93 kW with the state of charge at zero, ramped all the way up to 256 kW at 41 percent, then didn’t drop below 90 kW until state of charge reached 81 percent. Likewise, Out Of Spec’s testing of a Kia EV6 AWD showed it ripping up to north of 200 kW, not dropping below 90 kW until the state of charge reached 87 percent. As for the F-150 Lightning, apart from a weird trough at precisely 22 percent state of charge, it didn’t consistently fall off below 130 kW until 45 percent state of charge in Out Of Spec’s testing.
So what have we learned here? Well, temperature matters, EV charging equipment matters, and performance in the winter probably will see a decline over fair weather performance. As it stands, if you live in a place that gets winter and have access to Level 2 charging at home or at work, you probably don’t have to worry about DC fast charging all the time. However, if you live in a place that gets winter and can’t charge at home, consider that it might take longer to DC fast charge an EV in the winter before you sign on the dotted line.
Top graphic image: Ford
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So modern EVs will pre-warm the battery to improve charge speeds when they know they’re heading to a fast charger. In a road trip situation that should maintain charging speeds at near-optimal, less the additional energy needed to heat the pack. Going to a DC fast charger immediately after a long cold soak is definitely not ideal and hopefully not a usual use case.
How much heat is generated during normal highway use? Might that be enough with better insulation?
Dummy question, but a lot of Canadian ICE cars are outfitted with block heaters. In terms of inconvenience, isn’t slower charging of EVs basically an analogy to that? Just part of dealing with the hassles of the climate. Similarly, if the batteries aren’t “smart self-heating” prior to use, then there’s a good case for something like a Nest thermostat or something.
Sure but being cold in the car vs not driving the car. Our lyriq definitely loses range and slows down in the colder weather, if I had to take it somewhere to charge I would absolutely not bother but charging in our parking garage means it’s a minor inconvenience for daily use at best.
What is this cold you people speak of? It was cold today. 63 here in San Jose. Freezing? That’s why you drive to the mountains so you can experience it.
Hey now! Sometimes there’s a frost!
“Tested them from 20 degrees F to five degrees F”
OK, enough with the summer testing, let’s bring on the cold!
Disclaimer: I don’t feel like I can make cliche Canada jokes anymore without the disclaimer that we love you guys and are really sorry for the hassles lately.
One day soon we’ll all be sitting around in an igloo together, hiding our Timbits, Molsons, and first-pressing Rush vinyls from the polar bears attacking us.
What, no Tim Horton’s Maple Poutine surprise?
I’m out!
I have an EV, and I deal with this… but it just goes to show how far they really are from being truly market ready. I own my house and installed a charger in it, which is great, but it would be completely unusable if I didn’t. I’m willing to put up with things, and I’m happy I am, but it’s also not my only car…
The truth. I love my ioniq 5, but if you can’t home charge, evs don’t make sense.
It does increase charge time. If the battery is cold soaked all night under 30 degrees and you immediately go to charge it will just warm the battery when you plug in and can take a while to even begin charging. That is not a likely scenario though.
When I fast charge after a shorter drive it adds like 5 minutes to charge time. Obviously for other cars it can vary quite a bit.
Modern EVs have thermal management so it can be an issue in some scenarios and undoubtedly extends charging times, but this is another likely overstated issue. If you need a charge for a trip after the car sits for a long time, then its better to just charge the night before so you can warm up the vehicle in the morning for the drive and then charge.
Solid State Batteries can’t come soon enough.
The data is all well and good, but one thing left out here is WHY charging rates drop when temperatures are cold.
Lithium batteries charge best when they are fairly warm, so if the car has been sitting all night in sub-freezing temperatures, a fair amount of power is needed just to warm the batteries up to temperature. How that’s done depends entirely on battery design, but since most battery packs are liquid-cooled, it means heating the coolant (either directly with resistive heat or via a heat pump) and circulating that coolant.
However, if the car has been driving a while in the cold, and its batteries are already up to temperature when it reaches the charger, much less power and time is needed for that pre-conditioning.
I experienced this with my Mach-E trying to use a level 1 (120V charger) at a cabin while on a trip in the mountains. Basically, with the car sitting cold, it needs nearly all of the 1500W draw just to keep the batteries warm, so the actual amount of power put into the batteries is almost zero. The car gave an estimate of like 4.5 DAYS to charge, lol. It was effectively just setting a space heater out in a blizzard.
Also note that DC chargers have internal coolant lines around the cord to cool it down. I’m curious what the current draw is on the station cord cooling system when it’s in freezing weather.
I solved the Mach-E charge issue by driving a few miles to a DC fast charger, where 30minutes on the charger was plenty of charge to get me home. It was a total non-issue, but it was interesting to see how much power it takes to condition batteries for charging.
Sounds like the solution is better thermal insulation around the battery pack. Maybe that’s something you could do? Perhaps placing a fitted block of Styrofoam under the battery and blankets inside.
My homebuilt EVs all require the battery to be above 32F in order to charge, or they will be destroyed.
In the case of the LiIon packs in my ebikes, dendrites will form on the anode if they are charged below 32F.
In the case of the CALB CA100FI LiFePO4 pack in my Triumph GT6 conversion, I can charge below freezing at a trickle of 0.1C without damage. Any faster, and I will destroy one of the terminals and the battery will have so much resistance that it won’t function. I have not tried this, mind you, but have read about it when researching just how robust these batteries are. People have found that this particular LiFePO4 battery will accept a slow charge blow 32F without damage, but that is at roughly 1/5th the rate they can actually charge without a shortened lifespan according to the spec sheet(0.5C rate according to spec sheet, but the spec she was overly conservative and these batteries can handle about twice the charge and discharge rate than the spec sheet recommends). That pack was way too expensive for me to experiment on it in that manner. I plan to implement a battery heating system in it before completing the car.
A properly designed battery pack will have resistive heating elements and standardized sensors that can send data to a charger. The battery heaters could come on if the battery/charger senses that the temperature is too low to charge. This doesn’t require complex software-driven electronics to implement, and can be done with off-the-shelf inexpensive golf cart parts.
Waiting for thee batteries to heat up before charging will increase the duration of the charge cycle.