How Does the Cold Weather Affect EV Car Battery Performance?

For a lot of EV drivers, winter will result in a noticeable reduction in the usual range of their electric cars. On top of this, many will find that their charging stopovers take longer, increasing journey times and reducing overall efficiency. If you’ve ever noticed this, then don’t worry, there’s nothing wrong with your EV. Unfortunately, the cold weather effect on EV batteries is real and noticeable. However, in this guide, we will explore the reasons behind this apparent reduced EV  battery performance and how best to tackle it.

Why is EV range lower in cold weather?

In short, there are several reasons why your EV has reduced performance in the winter. These include:

• Reduced battery performance & charging time due to cold weather.
• Additional heating, wipers and lights all require more energy to operate.
• Wet, icy or snowy conditions can increase energy usage by up to 10%.

Why does my car charge more slowly in the cold?

As an electric vehicle (EV) owner, it’s likely you will have experienced trying to fast charge during the winter, and not receiving as quick of a charging speed as the stated power on the charger. This is in fact a very common problem during colder periods. And here’s why…

The EV runs the show

First and foremost, it is important to remember that when it comes to EVs – the car is in charge, not the driver. 

A charger can always provide its stated power, but an EV decides how much power it will accept. Essentially, electric vehicles themselves regulate the charging process to protect the battery – and so the speed of charge varies throughout a charging session. We call this an electric car’s ‘charging curve’. 

During winter, there is one core reason fast charging is slower than at any other time of the year – and that’s ‘battery temperature’. 

The temperature of an EV’s battery greatly affects the charging speed. In the depths of winter, it can often drop considerably below zero degrees, especially at night. An EV battery has an ideal operating temperature, preferably around 20-40 degrees Celsius depending on the car model, which can be difficult to achieve in winter. If the temperature is lower than this, it will affect both charging speed and range. This is because the electrochemical processes in the battery slow down as the temperature drops, meaning it can neither take nor deliver its charge as quickly.

Many people park their car outside or in an unheated garage, resulting in the battery temperature matching that of its surroundings. As a result, the EV must use a lot of energy to reheat the battery. 

As a general rule, an EV battery won’t reach the ideal operating temperature on a normal drive in negative temperatures. So, when you come to charge your vehicle, some of the power from the charger goes to heating the battery instead of charging it. Consequently, charging takes longer when you arrive at the charging station. After charging at a fast speed for a while, the battery will have reached operating temperature, which means the range should be better and you’ll be able to fast charge at the expected speed next time.

How can you avoid slower EV charging speeds in winter?

It’s generally difficult to avoid the effects of cold weather on EV batteries in winter, but there are some ways to improve slow charging.

1. Preheat the battery

Many EV models offer drivers the opportunity to preheat the car’s battery, either before you go out for a drive or while you are on your way to a fast-charging station. Your car will then prioritise heating the battery so that it reaches operating temperature, meaning power won’t be diverted while charging. We highly recommend preheating your EV’s batteries if your model allows for it.

There are several EVs on the market with battery pre-heating functionality, including almost all newer ones. However, if you have an EV from one of the following manufacturers, it’s likely it will have preconditioning:

• Tesla
• Chevrolet
• VW
• Audi
• Porsche
• Nissan
• Renault
• Ford
• Jaguar
• Hyundai
• Kia
• BMW
• NIO

2. Wait to charge

If you’re not able to preheat your EV’s batteries in advance of a trip, we recommend waiting as long as your vehicle will allow before you carry out a charge. This way, the battery at least has time to get lukewarm – making charging both better for the battery and faster. If you have a home EV charger, consider plugging it in as soon as you get home from a journey, to make the most of the warmer equipment. The same is true if your workplace has a charger. By plugging in after your drive to work, you’re making the most of a warm car, and also charging during the warmest part of the day.

It may also be a good idea to use regeneration to assist in heating up your battery. And fast acceleration can help increase the temperature – without us wanting to encourage rough driving, of course!

3. Park the car indoors

Obviously, not everyone will be fortunate enough to be able to do this, but if you have the opportunity, we’d definitely recommend parking your EV in a warmer environment. This will ensure that the batteries do not get as cold, and you do not have to spend as much energy on heating them! If you have a garage but it’s not heated, a plug-in storage or low-power heater could be what you need to raise the temperature by just a couple of degrees.

Alternatively, using a car cover overnight may help to keep the temperature of the car a little bit warmer – even small differences can help. And as a bonus, you won’t have to defrost the car in the morning!

EV battery range in the cold weather – how can you maximise it?

As mentioned, winter also leads to a reduction in the range you are used to with your EV. So how can you counteract this? Luckily, there are some tips for EV battery maintenance in cold weather.

1. Preheat the car

You might not want to hear this, but the biggest energy sucker is your heater… In fact, Renault estimates extreme heating or cooling of your EV can reduce range by 30%. 

Therefore, it can be a good idea to start preheating your EV in the morning while the car is still plugged into the charger. This way, the battery also gets hot when you start driving, and the car doesn’t have to use electricity from the cold battery to heat it up. 

If it is cold in the car and you haven’t turned on the preheating, a seat heater is a good alternative to the main heater. It requires less power, and therefore does not use as much of the battery as the heater does, while still helping to reduce the negative effects of a cold EV battery.

2. Driving conditions increase energy consumption

Unfortunately, there’s not much that can be done about this one, regardless of how cold or warm your battery is. In the winter, the road can often be wet or covered with snow or slush – meaning that energy consumption can quickly increase by 10% or more as a result of the traction and stability control working harder. The surface is therefore an important reason why many people experience a shorter range in winter. 

Regardless of the season, it is also vital to check the air pressure on your tires – too little air will increase rolling resistance and increase the energy consumption of the car. It’s very quick and simple to make sure your tires are correctly inflated, but it can have a big impact.

3. Adjust your driving style

There are several tips for driving an EV in cold weather. For example, avoid heavy braking and acceleration. Essentially, try to drive as smoothly as possible. You can save a lot of power with a quiet driving style – high speed leads to increased air and rolling resistance, which in turn increases energy consumption. If you find it difficult, you can try switching on your EV’s eco-driving program. This slightly reduces the effect when you step on the accelerator pedal, as well as automatically reducing the heat.

4. Let the EV battery get hot when you can

Remember to always charge the car when the battery is hot. The electronics in the car will protect the battery from a high voltage charge if you try to charge when it is cold – and so the car will reduce the power. Therefore, always charge the car after driving for a while and before parking it.  

Not that range can also be affected by other factors such as extreme heat, cabin load, and more. We recently looked at how long EV batteries last in detail and how you can protect their health day-to-day and long-term. 

How much does cold weather affect electric car range?

It varies, but the American Automobile Association conducted a study that suggests that at 20 degrees Fahrenheit (-6.5 Celsius), an EV can lose up to 12% of its range. If you turn the heater up to heat the cabin, this can drop to 40%!

How cold is too cold for an EV battery?

We’ve already seen that winter can affect the range and performance of an EV, but what’s the lower limit when it comes to EV battery performance in extreme cold weather? 

Unfortunately, There isn’t a hard figure, as there will likely be various factors such as the state of charge (how full the battery is), the inclement conditions, and the time of day. However, GEOTAB has conducted an analysis of the range of thousands of EVs, and found that even at -20 Celsius, owners should still expect around 40% of their usual range. 

Therefore, unless you live in a part of the world with the most extreme temperatures, it’s very unlikely it will ever get so cold that your car stops functioning.

How to avoid the effects of a cold EV battery when charging

• Do what you can to charge the car when the battery is warm.
• Alternatively, preheat the battery before charging.
• Keep the car in a garage, or at least under a cover when not in use.
• Heat the people, not the car! Avoid the main heater and use heated seats instead.
• Drive more slowly, avoiding heavy acceleration and braking.
• Use your car’s Eco-mode.
• Make sure your tires are inflated to the correct pressure.

As you can see, the winter can have an effect on your EV’s performance, but there are certainly ways to help minimise the impact. Having access to a range of reliable and convenient EV charging solutions will help you to charge your car at the most optimum time to increase performance and save money.

For more information about what to do in the summer months, read our Driving and Charging an EV in Hot Weather guide, or check out the rest of our news and resources.