Winter is coming, and if you own an electric vehicle, you have to start gearing up—but why?
Well, because the performance of your electric vehicle takes a toll when the temperature starts to fall, and there are a few things that are important to know about using and caring for your electric vehicle in the winter.
How Much Range Does Your Electric Vehicle Lose Due to Cold Weather?
If you have used a smartphone in frigid conditions, you know that battery performance takes a hit when the temperature goes below sub-zero.
As electric vehicles use similar battery chemistries, their performance also decreases as temperature decreases. Not only this, according to tests conducted by the American Automobile Association (AAA) in 2019 [PDF], the driving range decreased by 12 percent at 20 degrees Fahrenheit when compared to 75 degrees Fahrenheit. This decrease in range increased to 41 percent when the cabin heater was used.
Therefore, it's safe to say that the range of your electric vehicle decreases when the weather outside is cold, but why does this happen?
Well, there are two main factors, but before getting into it, let's try to understand Lithium-ion batteries.
How Do Lithium-Ion Batteries Work?
Put simply, the battery on your vehicle converts chemical energy into electrical energy. To do this, it uses three things a cathode, anode, and an electrolyte.
The anode forms the battery's negative terminal and has a high density of electron-rich lithium atoms. These atoms are trapped in a layer of graphite and want to get rid of their one valence electron to become stable. This tendency of atoms to lose electrons is known as electropositivity, and lithium being a metal, is very electropositive.
On the cathode, we have cobalt-oxide that forms the positive terminal. This terminal is positively charged as the cobalt atoms have lost electrons to oxygen and have a high tendency to gain electrons. This tendency of an atom to gain electrons is known as electronegativity.
To summarize, the lithium atoms at the anode want to lose electrons, whereas the cobalt on the cathode wants to gain electrons. Due to this, electrons move from the negative terminal to the positive terminal, and it is this movement of electrons that generates electricity.
In addition, an electrolyte is placed between the anode and the cathode, which enables the lithium ions to move from the anode to the cathode.
The aforementioned process happens during discharging, and the exact opposite happens during battery charging.
Why Does the Range of Your EV Decrease in the Winter?
Now in a hypothetical environment, the above reaction should keep running forever, but as we all know, batteries don't last forever. This is due to other reactions that consume the electron-rich Lithium atoms, degrading battery performance. These reactions occur at different rates at different temperatures.
Therefore, cell manufacturers define a range of temperatures in which batteries can function optimally. For lithium-ion batteries, the discharge temperature is between -4 and 140 degrees Fahrenheit, while the charging range is between 0 and 45 degrees Fahrenheit.
This clearly shows that lithium-ion batteries can discharge at sub-zero temperatures, but charging them at the same is not advised. Also, lithium-ion batteries offer the best discharge performance at room temperatures, and in extreme situations, their performance degrades.
The reason for this degradation is as follows.
When you charge your lithium-ion battery, the charger pulls lithium ions from the cathode, converts them to lithium atoms by adding an electron, and embeds them into the graphite on the cathode.
When the temperature decreases, the lithium atoms don't intercalate in the graphite; instead, they coat the surface of the anode causing lithium plating. This lithium plating phenomenon converts the otherwise electropositive lithium atoms into an inert metal. Due to this, the number of lithium atoms available for providing free electrons goes down—decreasing the battery's performance.
Lithium plating increases when a high charging current is used.
On the other hand, when your battery discharges, the lithium ions have to move from the anode to the cathode. During this process, the ions have to move through the electrolyte, but when the temperature decreases, this process slows down as the resistance of the electrolyte increases. This increase in resistance reduces the range your EV offers.
In addition to the factors given above, the battery is responsible for keeping the cabin warm when the weather outside is cold. Due to this, the battery has to run both the vehicle and the heating system, reducing the range further.
10 Things You Can Do to Improve Your EV Experience in the Winter
Now that we have a basic understanding of why the performance of your EV goes down when the temperature goes below sub-zero, we can look at how you can improve your EV experience in winter.
1. Don't Fast Charge Your EV in Cold Temperatures
As explained earlier, Lithium plating is a battery's biggest enemy during cold weather conditions. Not only this, but the phenomenon increases when the charging current is high.
Therefore, it's advised that you should not fast charge your electric vehicle when the ambient temperature is below freezing
2. Charge Your EV Slowly at Night
If you plan to travel long distances on your EV, it's best to charge it to the brim at night using level 1 charging. Not only will this provide you with a full charge in the morning, but it also provides a slow charging current that won't damage the battery.
Not only this, but if you don't have a heated garage to charge your EV, the slow charging will keep your battery warm, protecting it from cold weather conditions.
3. Be Prepared for Longer Charging Time
As the electrolyte on your battery gets sluggish in colder weather, it takes longer to charge. Therefore, you should be prepared for a longer charging duration while charging in colder weather conditions.
4. Don't Leave Your Battery Discharged in Cold Weather Conditions
If you are not going to use your vehicle for a long duration, it's advised to charge it to 70 percent before storing it. Doing this will reduce the reactions which degrade your battery's health.
In addition to this, you should not leave your vehicle with a low battery percentage at night as it damages your battery's health.
5. Park Your Vehicle in Heated Spaces
If you have a garage where you can keep your car at night, it's advised to maintain the ambient temperature between 68 and 72 degrees Fahrenheit.
Doing this will reduce the internal reactions that degrade your electric vehicle's battery, offering better battery performance over a prolonged period.
6. Preheat Your EV Before Going Out
Before leaving for work, it's best to preheat your car slowly while you do your daily chores. Not only would this keep you warm when you go out, but as the car is heated slowly, the battery pack won't be under much stress when driving.
In addition, you can also connect the charger to your car while you heat it so that the power is drawn from the charger and not the batteries, offering you more range for the day.
7. Keep the Heat on Low
If you are planning to take a road trip in the winter, the heater on your car is the battery's biggest enemy. Although it keeps you warm, it degrades your battery's range.
Therefore, rather than running the heater at full throttle, it's best to use the heated seats and steering wheel to keep your hands and body warm. This could increase your EV range, and you won't have to charge your vehicle that often.
8. Use Lower Levels of Regeneration Breaking
Most electric vehicles offer different levels of regenerative braking. This enables the EV to charge as its brakes are applied. That said, if you are driving in cold weather conditions, a higher level of regeneration can cause your vehicle to skid on snowy surfaces.
Also, the high level of regenerative braking would supply high currents to the battery, which could damage it due to the colder temperatures.
9. Use Eco Mode
If you are not planning to drag race on your EV, it is best to turn on ECO mode when the weather outside is cold. Doing this would provide better range and decrease the load on your battery – offering better battery health.
10. Go Through the Internal Combustion Engine(ICE) Checklist
Although driving an electric vehicle is a different experience from an ICE, it still has external components like tires and windshield wipers, which don't fare well in cold weather. Therefore, getting a new pair of wipers and snow tires is advised.
Is It Safe to Drive an EV in Freezing Conditions?
An electric vehicle offers users a different driving experience and comes with many bells and whistles. That said, cold weather is an electric vehicle's Achilles heel as it hampers the chemistry of the battery pack that powers it.
Electric vehicle owners can get the best out of their vehicles equipped with intelligent battery management systems and best EV handling practices.