Winter Tips for Electric Vehicles

Is your EV ready for snow and ice?
It's mid-October in Michigan and the morning school run is made in darkness.  Raindrops reflecting the headlight beams looks like I'm driving through hyperspace.  The trickle of drops hit the windshield ... only they're not drops.  They are flakes.  

Those of us who live in colder climates know that as the golden leaves drift gently to the ground, we need to start thinking of winter habits.  Electric vehicles (EVs) have some special considerations.

Range

The most pronounced effect of colder temperatures on EVs is range.  Depending on your vehicle, temperature, and situation, the range loss may be as much as 30-40%.  

While cabin heating does take a toll on range, it's not necessarily the primary range thief, so just wearing extra clothing and leaving the climate control off won't give you summer range.  As most EV drivers know, higher speed means higher air resistance and thus lower range.  This effect is exacerbated by colder denser air when the mercury drops.  Battery charge and discharge is an electrochemical process that is less efficient at lower temperatures.  Rolling resistance increases when the car's tires needs to plow through snow and slush.  Reduced range in colder weather is caused by a combination of all these effects combined.   

Figure out what your car's range is in colder weather.  Turn range anxiety into range awareness. 

Read on to get the most out of your EV in the cold.  

Keep charge ports clean.
Charging

Since your EV will consume more power in cold weather for the equivalent warm weather miles, keep your battery topped up.  Frequent charging can also keep the battery a bit warmer from residual charging heat.  Even a 1.5 KW "granny charger" plugged into a standard household socket helps.  

Charge Timing

If you have a charge timer for overnight charging, set it so that charging ends just before departure time.  While battery charging is very efficient, the minor resistance losses are turned into heat and can help warm your battery resulting in slightly more range.  A warmer battery means more range.

If you are taking advantage of preferential nighttime power rates, you may want to balance delayed charging with finishing the charge before power rates go back up to daytime rates.  My rates return to peak rates at 7 AM, so I try to time my charging to end around that time.  

DC Fast Charging

One exception to the "charge right before you drive" strategy is if you are using a DC Fast Charger (DCFC).  In very cold weather, the battery will "cold soak" overnight meaning that it cools to near the ambient temperature.  When charging, the car's battery management system (BMS) will likely reduce the maximum charging power to avoid damage to a cold battery.  Ideally, you would charge on a Level 2 charger overnight.  However if your accommodations are near a DCFC or Tesla Supercharger, you have to choose to charge before or after your overnight stay.  Given the choice, charge the battery most of the way (say 80-90%) the night before letting it sit or be prepared for a long charging session in the morning.  If possible, top up the rest of the way while getting ready in the morning, even if it's just a standard 120V outlet the will compensate for the power used by your climate control.

Because your car is using more energy for the same distance, allow yourself more time to charge.  In some cases, you might need to stop more often.  On our Tesla summer road trips, we often skip Supercharger locations along our route simply because we don't need to charge.  In winter, we often make an extra stop to top up a few minutes while we get some snacks and have an additional pit stop.  

Most EVs have remote 
preheating options.
Pre-Heating

Using the climate control to heat your cabin consumes a significant amount of energy.  If possible, preheat your car while it's still connected to grid power thereby preserving your battery for driving range.  Most EVs have the ability to either preheat remotely with an app and/or a preheat timer you can set the night before.  In addition to the pleasant experience of climbing into a warm car, this will preserve your battery charge for additional range.

Even when not connected to power, preheating can clear your windshield and avoid the need to scrape ice and snow.  Best of all, this can be done inside an enclosed space like a garage without noxious exhaust gases creating a hazard.

Traction

For the most part, driving an EV in snow and ice isn't much different than an Internal Combustion Engine Vehicle (ICEV).  Most EVs are heavier with a lower center of gravity than their ICEV counterparts, so the handling is likely slightly better.  

Winter tires make
a huge difference!

Winter Tires

Just like any vehicle, an EV that encounters snow and ice service are much safer with a dedicated set of winter tires.  Yes, you can continue to run all-season tires, but they just won't have the same level of traction.  At a minimum, make sure you're not going into the slushy season with bald all-season tires.  Those are called no-season tires and will make your vehicle a hazard.

When choosing winter tires, consider a set with low rolling resistance optimized for EVs to avoid significant range loss compared to summer tires.  My personal favorite are Nokian Hakkapeliitta R3s (no affiliation or referrals; I'm just a happy customer).  They're not cheap, but the Finns know their stuff about winter driving and the range of my Nissan LEAF shod with the R3s is only slightly less on dry pavement than my stock summer tires. 

I have my dealer store my off-season tires and then mount them every spring and fall.  Some people choose to get an extra set of rims and just store the tires in their garage and mount them themselves when needed.  

Easy on the Go Pedal

Cars with electric drive trains have lots of torque at 0 RPM.  Spinning wheels deliver much less forward motion than properly gripping wheels.  If your EV has different drive modes, consider engaging one with reduced power mapping of the accelerator like "Eco" (Nissan) or "Chill" (Tesla).  

Turn down regen.
Turn Down Regen

One-pedal driving that makes use of automatic regenerative braking is one of the joys of driving electric. We all instinctively take our foot off the go-pedal when we want to slow down, but unlike ICE vehicles that just coast, regenerative braking can retard the drive wheels significantly, lock them up and cause the car to lose traction before we get a chance to compensate.   

Most EVs have some kind of setting for different levels of regen.  Think about turning down your regen in slick conditions.  My 2015 Tesla Model S has the option of "standard" and "low" regen.  On my 2016 Nissan LEAF, I stick with "D" on slick roads rather than the "B" mode which has more aggressive regen.  My daughter's Chevy Volt has an "L" (low) gear selector setting that has more aggressive regen.  "D" is a better choice in slick conditions.

Maintenance

Make sure your 12V battery is in
good shape.  A jumper pack can
get you out of trouble.
12V Battery

While the traction battery on EVs requires no maintenance, your EV still has a secondary 12V battery just like an ICE vehicle.  Cold temperatures affect not only lithium-ion battery performance, but lead acid batteries as well.  The 12V battery runs your vehicle's auxiliary systems like climate control, lights, wipers, and - most importantly - the vehicle's computer.  Even if your traction battery has a full charge, if your 12V battery is dead, the car is a brick and won't start.  

Check the condition of your 12V battery before the cold weather hits.  Any decent auto parts shop should be able to run a check for you.  Most will do it for free in hopes of selling you a new battery.  If you do need a new one, they often have free installation with purchase of a battery as well.

If your car does seem to have lost power to all systems, you can get a "jump start" to give the 12V system enough power to wake up the computer and run the car's systems.  Jumper cables or a jumper battery pack is still a wise thing to have with you, even if it's just to help a poor ICE motorist in a pinch.  Think of the educational potential for the latter scenario.

Winter wash fluid 
helps clear frozen windshields.
Windshield Wiper Blades and Washer Fluid

ICE vehicles convert about 80% of the fuel value into heat, so there's plenty to divert onto the windshield.  EVs often run cabin temperatures cooler, so it's a good idea to start to add washer fluid with a temperature rating well below normal nighttime low temperatures.  Here in Michigan, -20°F rated washer fluid is usually sufficient.  Keep in mind that if you're adding winter fluid to summer fluid already in the tank, the latter is optimized for bug removal and not ice melting.  You won't get the advertised temperature rating until most of the summer fluid is purged out of the system.  Start adding winter washer fluid earlier rather than later.  Frozen washer jets and ruptured washer lines are a real drag.

Sensors covered with slush
don't work very well.

Snow Brushes and De-Icing Fluid

Snow brushes, ice scrapers and de-icing fluid are good for more than windshields and locks.  Carry a brush and some lock deicer to clear away any snow and ice from your charge port.  Carry an extra bottle of windshield washer fluid as it will work to melt ice from charge ports as well.  

For Tesla owners who have the clever windows that retract when you engage the door handle and pop back up when you close the door, make sure you de-ice the area where the window retracts into the door frame.  Window glass is even more brittle in the cold, and a shattered window makes a cold day driving worse.  

Slush, ice, and snow can build up on driving assistance sensors like Tesla's autopilot.  A brush and some de-icing spray can help clear those off during pit stops.  Be careful around plastic parts with an ice scraper.  They get more brittle in colder weather and can snap off with vigorous ice removal.

Got Other Tips?

Please leave them in the comments or share them on the West Michigan EV and Plug-In Vehicle Enthusiasts Facebook Group.


Resources:

If you are in the market for a Tesla Model S, Model X, or Model 3, Tesla has reestablished its referral program.  Feel free to use my referral code to get free Supercharging (at the time of this publishing) for your Tesla:  http://ts.la/karl5062

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