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Is fully charged without driving bad for EV battery?

lithium-ions-moving-in-battery

The Significance of Activity for Both Cars and Humans

Just as people often say that cars, like humans, fear idleness more than activity. Being stationary for a long period can potentially cause issues while an active state can aid healthy circulation, preventing many problems. This concept applies perfectly to electric vehicles (EVs) as well, particularly when it comes to their batteries.

EV-battery
EV battery

The “Fully-Charged” Habit That Harms EV Batteries

Is fully charged without driving bad for EV battery? Common sense would dictate that if a battery isn’t going to be used for an extended period, it should be fully charged for peace of mind. However, for electric vehicles, this isn’t a good habit. If you leave your EV idle with a full battery for a long time, it can degrade the battery faster. As a professional EV charger manufacturer, we will explain details in today’s blog post.

How a Lithium Battery Works

Lithium-ion-working-diagram
Lithium ion working diagram

The accompanying diagram illustrates a lithium battery‘s inner workings. The lefthand side, the cathode, hosts a lithium compound. The anode, on the right, is made of graphite. Under the influence of charging, the active lithium atoms shed their peripheral electrons, a journey that ends at the anode. Meanwhile, lithium ions, now positive, follow the anode’s negative pull and migrate from the electrolyte to the anode.

When an external power source moves all lithium ions to the anode, the lithium battery is fully charged. Cutting off the power source, the electrons “regret” their departure. They want to return to the cathode but cannot cross because the internal circuit isn’t complete and the cathode and anode have a separator in between – so they stay put at the anode.

The-Process-of-lithium-ions-Discharging
The Process of lithium ions Discharging

The Process of Charging and Discharging

While charging, the lithium atoms are drawn to the negative electrode, traveling along the conductor due to the charger’s attraction.

Once all the lithium ions have been attracted to the negative electrode under the influence of an external power source, it signifies the battery is fully charged.

During discharge, when the battery circuit is closed, the electrons are delighted to return to the positive electrode.

The-Process-of-lithium-ions-Charging-and-Discharging
The Process of lithium ions Charging and Discharging

The Role of Lithium Ions

You would notice that the lithium battery effectively utilizes the movements of lithium ions and electrons along different paths – the lithium ions move through the electrolyte, following a “water route” and the electrons move along the external circuit, following the “iron route”. The more freely the lithium ions can move within the battery, the less the battery’s capacity is affected.

Fully Charged Without Driving Bad for EV Battery

Why do Lithium Batteries Degrade when Fully Charged over a Long Period of Time?

This is because when a lithium battery is fully charged, most of the lithium ions move to the negative electrode, and in the process, the lithium compound at the positive electrode loses lithium ions, making it unstable.

lithium-ions-moving-in-battery
lithium ions moving in battery

In the long run, this unstable compound at the positive electrode worsens the reaction with the electrolyte. Eventually, when the battery is discharged, some lithium ions returning to the positive electrode find no suitable place to stay, thereby affecting the battery’s capacity. Therefore, lithium batteries should not be stored fully charged for a long period of time.

Conclusion

Popular electronic products usually arrive with about half of the battery’s charge. This isn’t due to frugality but instead, an attempt to prolong the life of the lithium batteries.

Fully-charged-without-driving-bad-for-EV-battery

Also, it’s specified in the user manuals of electric vehicles not to fully charge the battery if the car is going to be inactive for a long time. Instead, it’s advised to maintain a half charge, as it beneficially influences the battery’s lifespan.

So if you know that your new energy vehicle will be idle for a while, do not fully charge its battery. Instead, discharge it to half the capacity as specified in the vehicle’s manual. This strategy can help extend the battery’s life.

FAQs

Is it bad to leave an electric vehicle fully charged without driving it?

Yes, it can degrade the battery faster if it’s left idle for a long time.

What happens to the battery if an electric vehicle is fully charged but not driven?

The battery’s structure can become unstable, which can react negatively with the electrolyte.

How should I maintain my battery if my EV is not in use?

Discharge the battery to half its capacity if you’re not going to use the car for a while.

Is partially charging my EV battery before a period of inactivity beneficial?

Yes, maintaining about half capacity before inactivity can extend your battery’s life.

What is the ideal state at which I should keep my EV battery during long-term storage?

It’s best to store your EV with the battery charged to about 50%.

Why does my electronic product arrive with about half of the battery’s charge?

This is to extend the lifespan of the lithium battery in your electronic device.

Does fully charging an idle EV battery decrease its capacity?

Yes. In the long run, it can make the lithium compound at the positive electrode unstable.

Do all electric vehicles have guidelines regarding battery care in their user manuals?

Yes, typically, user manuals specify not to fully charge the battery if the car is to be inactive for a long time.

Can I ignore these precautions if my EV uses a different battery type?

Most current EVs use lithium-ion batteries, but it’s best to follow your manufacturer’s advice, regardless of battery type.

How does overcharging affect the performance of an EV battery?

Overcharging, especially before an extended period of idleness, can cause the battery to degrade faster and impact its overall capacity.

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Leo Chen

Leo has rich experience in the field of EV charger industry.

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