Do electric cars lose charge when parked?
Electric cars are revolutionising the automotive industry, offering eco-friendly alternatives to traditional combustion engines. As consumer preferences steer towards greener transportation in the leadup to the 2035 electric car switchover, electric vehicles (EVs) are something every driver needs to know about.
Updates in technology mean that electric vehicles (EVs) can go farther than ever on a single charge. This means that more drivers can wave goodbye to range anxiety and say hello to the open road. Even with better range, proper vehicle maintenance is essential to keeping EVs in top shape.
To optimise electric cars and vans performance, battery upkeep is crucial. Whether you own an EV or are looking to buy or sell an electric vehicle, get to know what factors affect charge retention while parked.
But what does it mean for a car to be ‘rare’? Delve into the world of automotive exclusivity and see how you can preserve your vehicle’s value below.
EV battery basics
Your battery is the powerbank of your car, igniting your engine and allowing you to move from A to B. Car batteries are hugely important in any vehicle, but especially in battery-electric vehicles. In petrol or diesel cars, batteries are primarily used to start the car and power features like the radio, whereas in EVs batteries power all vehicle functions. High performance is therefore crucial to getting your EV started and experiencing its full range.
Most EVs use a high-voltage lithium-ion battery. Lithium-ion batteries are designed to have long lifespans and are less likely to lose their charge when not in use. They also typically have extended warranties. Most manufacturers offer warranties that cover EV batteries for 100,000 miles or seven to eight years, whichever comes first.
See below for manufacturer warranties for popular UK electric car models (as of July 2021):
| Model | Warranty |
| Tesla Model 3 | 8 years/ 100,000 miles |
| Kia e-Niro ‘2’ | 7 years/ 100,000 miles |
| Mini Electric (2020) | 8 years/ 100,000 miles |
| Smart EQ ForTwo (2018) | 8 years/ 62,500 miles |
EVs can be charged privately at home or at public charging stations. Some vehicle manufacturers also run their own charging networks; Tesla, for example, boasts the largest and most powerful charging network in the world.
Technological advances are bringing us closer to the dream of lightning fast battery charging. Currently, most UK public charging points are 7kW, meaning that it may take hours to fill your battery. However, public ‘power chargers’ can partially or fully charge EVs at a quicker rate. Tesla also sells an at-home charging point (or wallbox), which works on 22kW for speedy at-home charging. Check out our guide to electric cars with the longest range for more.
State of Charge
How do you know when your EV battery is charged? The State of Charge (SoC) refers to the level of charge stored in an EV battery at any given time, relative to its maximum capacity. EVs typically display SoC as a percentage, a feature that allows drivers to monitor the battery status to plan trips more efficiently.
Unsurprisingly, your SoC affects battery performance. Allowing the battery to reach extremely low SoC levels can result in reduced power output and driving range. Deep discharges can increase stress on the battery cells and accelerate degradation, ultimately reducing your EV battery’s overall lifespan.
Maintaining your battery within a moderate SoC range, typically between 20% and 80%, can help prolong battery life and optimise performance. Avoiding frequent deep discharges and extreme SoC levels can maximise driving range over the long term.
Battery drainage when parked
Electric cars may experience a gradual decline in battery charge when not in use. While parked, several factors can contribute to a decrease in battery power, albeit at a minimal rate. These include:
Temperature
Extreme temperatures significantly affect the efficiency and performance of electric batteries. In cold weather, batteries may lose charge more quickly due to increased internal resistance, which impedes the flow of electrons within the battery. This can lead to reduced energy output and decreased driving range. Cold also can affect the chemical reactions within the battery, further limiting its efficiency.
High temperatures accelerate battery chemical reactions and cause faster degradation of the battery cells. This degradation reduces capacity over time and can lead to a decrease in driving range.
Luckily, many modern electric vehicles are equipped with thermal management systems to regulate battery temperature. These systems help maintain optimal operating conditions for the battery, mitigating the negative effects of temperature extremes on efficiency and longevity.
Temperature can also affect charging efficiency. Charging a battery in extreme conditions can lead to slower charging rates and decrease its overall efficiency. EV manufacturers typically recommend operating the battery within a specific temperature range to maximise efficiency and longevity.
Vampire drain
Some EVs experience vampire drain, where onboard systems (like a car’s computer, sensors, and climate control) consume small amounts of energy, even when the car is not in use. This phenomenon can result in a gradual decrease in battery charge over time.
Other components like alarm systems, entertainment systems, and interior lighting can draw power from the battery when the vehicle is parked, reducing its overall charge.
Battery Management System (BMS)
The BMS plays a crucial role in monitoring and regulating the health of your vehicle’s battery pack. These systems help prevent overcharging, deep discharging, and other conditions that can degrade the battery over time. The BMS also helps balance the cells within the battery pack to ensure uniform performance and longevity.
However, some BMS algorithms may draw a small amount of power from the battery even when the vehicle is parked, contributing to charge loss.
Standby systems and electrical components
Certain features, such as remote monitoring and app connectivity, may require your EV’s systems to remain active even when parked. This can lead to a very slight drain on the battery.
Leaving electrical features such as interior lights or headlamps on after you’ve parked can also cause battery drainage.
Self-discharge
Self-discharge is the natural loss of battery charge over time, even when your EV is not in use. While modern lithium-ion batteries exhibit low self-discharge rates compared to older battery chemistries, it’s still a factor to consider, especially for EVs parked for extended periods.
Minimising battery drainage
Understanding how your battery works can help you make the most of your EV. Here are our top four tips for reducing your battery drainage:
✅ Maintain optimal charge level
Contrary to popular belief, consistently full or low charges can degrade EV battery health. Lithium-ion batteries degrade faster when consistently charged to 100% or depleted to 0%. Instead, aim to keep the battery between 20% and 80% charge for optimal longevity.
✅ Utilise power save modes and deep sleep features
Activating power save modes and deep sleep features can significantly reduce energy consumption while your EV is parked. These modes minimise standby power draw by shutting down non-essential systems, prolonging battery life and range.
✅ Deactivate unnecessary preset features
Disabling unnecessary preset features, such as remote monitoring and app connectivity, conserves energy by reducing standby power consumption. Deactivate these features while your vehicle is parked to minimise vampire drain and preserve battery charge for longer periods.
✅ Keep proper tyre pressure
Maintaining proper tyre pressure is crucial for maximising EV efficiency and range. Underinflated tyres increase rolling resistance, reducing efficiency and causing the vehicle to consume more energy. Regularly checking and maintaining optimal tyre pressure helps conserve energy and extend driving range.
FAQs
Can EV batteries maintain their charge indefinitely when parked?
No. EV batteries gradually lose charge when parked due to factors like vampire drain and temperature extremes, but not indefinitely.
How does weather affect parked electric vehicles?
Extreme temperatures – both hot and cold – can affect parked EVs by accelerating battery discharge and decreasing overall range.
Is it OK to leave an EV plugged in overnight?
Yes, leaving an EV plugged in overnight is generally safe and beneficial. It allows for convenient charging and ensures the battery is fully charged for the next day’s use, without risking overcharging.
If you’re unsure about how long to leave your battery charging, check with your manufacturer or consult your local mechanic.
How can I track the value of my car?
If you’re not sure what your car’s value is to begin with, it’s hard to know how its charging capability affects its price.
All vehicles depreciate at varying rates, with no rule of averages accurately describing any one car’s changing value. Motorway’s Car Value Tracker provides a free, reliable monthly price alert for up to six vehicles at once.
Follow changes to your car’s value to choose the best time to sell, and make informed choices about investments in your car’s maintenance.
Ready to sell your car?
Ready to learn more about valuing, maintaining, and selling your car? Check out more of our guides here, covering everything from hybrid and electric car depreciation, to converting your car to dual-LPG fuel.
- Sell my car
- Track your car value
- Electric cars – the ultimate guide
- How to sell an electric car
- How long does it take to charge an electric car?
- How & where to charge your electric car at home and on the road
- Electric car depreciation – comprehensive guide
- Do electric cars pay the congestion charge?