Can You Overcharge An EV?

Scroll ⟶

The growing popularity of electric vehicles (EVs) is good news. Especially for the environment. Lowered emissions mean a reduction in respiratory health problems and a positive impact on climate change. The cost of running an EV has also reduced, making it a more pocket-friendly option.

While those that opt to start their driving life with EVs will find their running easy enough, those making a switch from traditional fuel cars often need to relearn certain tasks. Rather than keeping an eye on the fuel gauge to know when to drop by a service station, they will need to track battery charge and ensure they make maximum use of their home charging station.

Most people still believe in the myth that overcharging the battery on their smartphone will cause damage. While this may have been true with older phones, the current models are better advanced and you can safely leave your phone on its charger for a long period without worry. Some have transferred this false knowledge to EV charging, suggesting that it overcharging can be a problem with their batteries. Given the higher cost of this asset, it is not surprising that people would worry about how this would affect their investment.

Is Overcharging Even Possible?

Just as with smartphones it is highly unlikely for overcharging to take place. This is thanks to technologies such as the in-built battery management systems. They effectively work to ensure the car’s main battery pack does not overcharge.

Under normal circumstances, when your car is charging, the rate slows down as it reaches near-full levels. Once the battery achieves full charge, the process switches to trickle charge. This is whereby the battery is recharged back up to 100% after some duration of discharging.

Even when the car is switched off, certain functions continue to run, causing the battery to self-discharge. The amount of charge used is very small. However, to ensure you set out the next day with a full charge, your battery management system will periodically recharge to full capacity.

What Happens When Battery Is Kept On the Charger for Too Long?

Most EV owners will plug in their car to their home charging station overnight. It is an easy habit that ensures you have a fully charged car to operate by morning, and you get to enjoy lower domestic tariffs during off-peak hours. This means lower energy costs associated with keeping your car running.

If your car was already nearly fully charged on returning home or if you do not end up using it for a long period, you may be wondering if there are consequences to leaving your EV plugged in for extended periods. There is no danger associated with leaving your car plugged in for a prolonged period. Even weeks at a time, the battery management system will see to it that overcharging does not occur.

So I Have Nothing To Worry About?

Yes and no. The technology today in EV vehicles makes it safe to have it plugged in for long periods. Even weeks at a time is not likely to be a problem. However, if this happens repeatedly, it may slightly affect battery degradation.

Car batteries do have a finite lifespan. The more charging cycles a battery goes through, the more it degrades with time. This means that amount of charge it can hold also reduces and consequently affects the vehicle’s range. Estimates indicate that EV battery packs can be expected to last some 200,000 miles. Chances are that by that time an EV owner will have upgraded or traded in for a newer model.

So How Do I Keep My Car Battery in Optimal Shape?

The majority of EV batteries are lithium-ion-based. These batteries perform most optimally when kept within a range of 50%-80%. Make use of the management and monitoring apps that work with your charging station and car. These can help in remotely controlling the parameters when charging. You can even set a lower maximum limit for charging before it should stop.

This is particularly helpful when using rapid charging stations. You can establish settings that will eliminate any fears of overcharging taking place. If your regular commute does not require a full charge, limiting your maximum charge to about 80% may help to prolong the life of your battery.

Also, avoid fully discharging your battery. Where possible, avoid allowing your battery level to fall below 30%. Deep discharging makes for more wear and tear on your battery, also negatively affecting its lifespan. And keep in mind that different brands and models come with varied designs. Make a point of going through your car’s manual for guidance on what best to do when charging.


Subscribe for EV Chargers news, events and more.