Do Electric Cars Lose Charge When Parked?


Every electric car owner or individual considering purchasing an electric car is worried about running out of charge. This could leave you stranded somewhere. Unlike an internal combustion engine, you can’t just have someone bring you a gas can full of gas and be on your way again. You need a way to hook your car up to power. This may mean needing to get towed if you are far from everything or bringing a generator to your dead car.

Perhaps, you charge your car up to 100% and then let it sit for two days before driving it. Will you still be at 100% charge? Do electric cars lose charge when parked? Electric cars will lose charge when parked though the charge that is lost is very small. Unless the electric car is parked for an extended period of time, the amount of charge that is lost shouldn’t be concerning for the driver and his/her ability to reach their next destination.

Generally, you know exactly how far you want to drive and how much range your car has, so this doesn’t ever become an issue. Although, you may have some concerns that while you planned to have enough range, your car might lose charge while it’s sitting parked. Imagine that you have to leave your car parked at an airport for two weeks while you are gone. Will you still have enough charge to drive back home when you get back? Or will you need to drive to the nearest charging station and then wait there for your car to charge when you really just want to get home?

Why Electric Cars Lose Charge When Parked

So, why exactly do electric car batteries lose charge over time? The answer has to do with the design of these batteries. Electric cars use lithium-ion batteries for controlling the motors inside of them. They work much like any other battery where they pass electrons between anodes and cathodes. Lithium-ion batteries are actually much more efficient than most other types of batteries. This means that your car won’t quickly lose charge when it’s parked.

One prime example of this is the lead-acid 12v battery that is used in cars. These can drain fairly quickly when not being used. As stated before, Lithium-ion batteries are much more efficient. If a lithium-ion battery is left at about 80% charge it generally won’t discharge much when not in use. This is generally a result of a battery monitoring system that will continuously monitor all of the cells in the battery.

The battery monitoring system is designed to prevent you from over-charging your battery or even over-discharging your battery and they also monitor the life and condition of the battery to help maximize its longevity. This system will continuously draw power, even when not in use. Systems like these are the main reason why your charge will drop even when not in use. Any other systems on your vehicle that stay on will also cause an additional toll on your batteries charge.

How Much Charge Can Your Car Lose When It’s Parked?

So, how much of your charge can actually be lost while parked? Fortunately, these batteries hold their charge for a very long period of time. If you are leaving it parked for the day, you likely won’t see any drop at all. If you are leaving it for several weeks, you will see some loss and if you are leaving it for several months, you can notice a very big drop.

In an ideal environment, most electric cars will only lose about 2-3% of their charge a month while sitting idle. That means that if you had a car with a 300-mile range, you could expect to lose about 6-9 miles out of your whole charge over the course of a month. Obviously, this is only under ideal circumstances. There are other factors that will come into play that can make your car battery hold as much of its charge as possible for as long as possible.

As you can see, the actual loss over time is small. Generally, you won’t really see the effects of this in your day-to-day use. If you drive to work and leave your car parked without being plugged in while you are there, you likely won’t see any drop in range at all by the time you climb back in. As lithium-ion battery technology continues to improve, we will likely see that loss of charge over time continues to decrease.

Does Temperature Play A Factor In Keeping Your Charge?

Does the temperature have an effect on how much charge that your car will lose while parked? It actually does. Previously when we mentioned ideal circumstances, one of the biggest factors is temperature. The ideal temperature would be a mild temperature. Too much heat and too much cold both put the car in a harder position to keep its charge.

High ambient temperatures can cause your battery to lose charge quicker. As components get hotter the charge will drop faster. Once you start your car, it will have to work much harder in order to cool the car back down. Both of these things will have an impact on the charge of your car. If it is all possible, it’s best to park an electric car in a garage or in the shade. Doing this will help keep everything cooler so you lose less charge.

Likewise, extremely cold temperatures will also have an effect on your car’s charge. In the cold temperatures, your car will have to continually warm itself to prevent it from getting too cold. As such, you will be draining your battery quicker than at a mild temperature. If you live somewhere very cold, keeping your electric car in a garage that is warmer than the temperature outside can help you to save as much charge as possible. The weather is usually the biggest reason why an electric car will lose charge while parked.

How To Prevent Losing Charge While Your Parked

So, what can you actually do to prevent your car from losing charge while it’s parked? The first thing that you can do is to keep it out of extreme temperatures as much as possible. If you are keeping the car at your house, putting it in the garage is a fantastic thing to do. In the summer, garages are generally cooler than outside, and, in the winter, they are usually warmer than outside. This helps protect your car from extreme temperatures that can damage your battery’s health.

If you are leaving your car somewhere not at home, there still are things that you can do to help keep it safe from the environment. If you can park in the shade or in covered parking, that will help your car to lose less charge. Try your best to keep it out of direct sunlight when you park. If this isn’t possible, it’s not that big of a deal. Your battery will just drain a little more than if you parked in the shade.

There also could be features in your car that constantly pull power from the battery of your car. One really good example of this is sentry mode on Teslas. This will constantly be consuming power from your batteries and can cause them to eventually go flat. If you have a feature like sentry mode and it is capable of being turned off, you may want to consider disabling it when you aren’t using the car so that it doesn’t drain your battery too much.

The last thing that you can do is to avoid leaving your battery fully charged while parking it for long periods of time. A battery that is charged to 100% will start to drop much faster than a battery that is charged to 80%. Generally, if you know that your car will be sitting for a very long time, it’s best to just leave between 40-80% charged. Doing this will make sure that it holds as much charge as possible for as long as possible.

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