Winter is coming and if you own an electric vehicle, you need to prepare, but why?
Well, as the performance of your electric vehicle takes its toll when the temperature starts to drop, there are a few things that are important to know about using and maintaining your electric vehicle during the winter.
How much range does your electric vehicle lose due to cold weather?
If you’ve used a smartphone in frigid conditions, you know that battery performance takes a hit when the temperature dips below freezing.
Since electric vehicles use similar battery chemistry, their performance also decreases as the temperature drops. Not only this, according to tests conducted by the American Automobile Association (AAA) in 2019 [PDF], driving range dropped 12 percent at 20 degrees Fahrenheit compared to 75 degrees Fahrenheit. This reduction in range increased to 41 percent when using the cabin heater.
So you can safely say that the range of your electric car decreases when it is cold outside, but why does this happen?
Well, there are two main factors, but before we get into it, let’s try to understand lithium-ion batteries.
How do lithium-ion batteries work?
Simply put, your vehicle’s battery converts chemical energy into electrical energy. To do this, it uses three things a cathode, anode and an electrolyte.
The anode forms the negative terminal of the battery and has a high density of electron-rich lithium atoms. These atoms are trapped in a layer of graphite and want to lose their one valence electron to become stable. This tendency of atoms to lose electrons is known as electropositivity, and lithium is a metal and is highly electropositive.
On the cathode we have cobalt oxide forming the positive pole. This terminal is positively charged because 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.
In summary, the lithium atoms at the anode want to lose electrons, while the cobalt at the cathode wants to gain electrons. This causes electrons to 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, allowing the lithium ions to pass from the anode to the cathode.
The aforementioned process takes place during the discharging process and the exact opposite happens during the battery charging process.
Why does your EV’s range decrease in winter?
Now, in a hypothetical environment, the above reaction should go on forever, but as we all know, batteries don’t last forever. This is due to other reactions that consume the electron-rich lithium atoms, decreasing the battery’s performance. These reactions take place at different rates at different temperatures.
That is why cell manufacturers define a temperature range 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 time is not recommended. Also, lithium-ion batteries offer the best discharge performance at room temperature, and in extreme situations their performance decreases.
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 places them in the graphite on the cathode.
When the temperature drops, the lithium atoms do not intercalate in the graphite; instead, they cover the surface of the anode and cause lithium plating. This lithium plating phenomenon converts the otherwise electropositive lithium atoms into an inert metal. This decreases the number of lithium atoms available to provide free electrons, decreasing battery performance.
Lithium plating increases when using a high charging current.
On the other hand, when your battery runs out, 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 drops, this process slows down as the resistance of the electrolyte increases. This increase in resistance reduces the range of your EV.
In addition to the above factors, the battery is responsible for keeping the cabin warm when it is cold outside. This requires the battery to power both the vehicle and the heating system, further reducing the range.
10 things you can do to improve your winter EV experience
Now that we have a basic understanding of why your EV’s performance declines when temperatures drop below freezing, let’s take a look at how you can improve your EV experience in winter.
1. Do not quickly charge your EV in low temperatures
As explained earlier, lithium plating is a battery’s worst enemy during cold weather conditions. Not only this, the phenomenon increases when the charging current is high.
Therefore, it is advisable not to quickly charge your electric car when the ambient temperature is below freezing
2. Slowly charge your EV overnight
If you plan on covering long distances with your EV, it’s best to charge it to the brim at night with charge level 1. Not only does this ensure a full charge in the morning, but it also ensures a slow charging current that does not damage the battery.
Not only this, but if you don’t have a heated garage to charge your EV, slow charging will keep your battery warm and protect it from cold weather.
3. Be prepared for a longer charging time
Since your battery’s electrolyte slows down in colder weather, it takes longer to charge. Therefore, you should be prepared for a longer charging time when charging in colder weather conditions.
4. Do not discharge your battery in cold weather conditions
If you will not be using your vehicle for an extended period of time, it is recommended that you charge it to 70 percent before storing. Doing this will reduce the reactions that deteriorate the health of your battery.
In addition, you should not leave your vehicle at night with a low battery percentage as it will damage the health of your battery.
5. Park your vehicle in heated areas
If you have a garage where you can park your car overnight, it is recommended that you keep the ambient temperature between 68 and 72 degrees Fahrenheit.
Doing so will reduce the internal reactions that affect your electric vehicle’s battery, allowing the battery to perform better over a longer period of time.
6. Preheat your EV before going outside
Before going to work, it’s best to slowly preheat your car while you go about your daily chores. Not only does this keep you warm when you go outside, but because the car is heated slowly, the battery pack will not be stressed much while driving.
In addition, you can also connect the charger to your car while you are heating it, so that the power comes from the charger and not from the batteries, giving you more range for the day.
7. Keep the fire low
If you’re planning a winter road trip, your car’s heating system is the battery’s worst enemy. While it will keep you warm, it will degrade your battery’s range.
Therefore, it is best to use the heated seats and steering wheel to keep your hands and body warm rather than running the heater on full throttle. This can extend your EV range and save you from having to charge your vehicle as often.
8. Use lower levels of regeneration interruption
Most electric vehicles offer different levels of regenerative braking. This allows the EV to charge while the brakes are applied. That said, if you’re driving in cold weather, a higher level of regeneration can cause your vehicle to skid on snowy surfaces.
Also, the high level of regenerative braking would deliver high currents to the battery, which could damage it due to the colder temperatures.
9. Using Eco Mode
If you don’t plan on racing your EV, it’s best to turn on ECO mode when it’s cold outside. Doing so will give you better range and reduce the strain on your battery, resulting in better battery health.
10. Go through the Internal Combustion Engine (ICE) Checklist
While driving an electric vehicle is a different experience than an ICE, it still has external components such as tires and windshield wipers, which don’t work well in cold weather. It is therefore advised to purchase a new pair of windshield wipers and winter tires.
Is it safe to drive an EV in freezing cold?
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 hinders the chemistry of the battery pack that powers it.
Electric vehicle owners can make the most of their vehicles equipped with intelligent battery management systems and the best EV handling practices.