Should you charge your EV to 100%?
You may already know that charging your smartphone to 100 percent is not good for its battery. The same thing (or rule) applies to your EV charging. Charging it to 100% can degrade its battery over time. However, you can keep the charge full only when necessary, such as for long trips requiring maximum range. Make sure to keep the battery charging level between 80% and 90%.
If you are still wondering why you should avoid charging your EV to 100%, let’s delve into this article to find out the reason, the recommended battery percentage for different EV brands, and when you can fully charge your EV.
How EV Batteries Work
The majority of the contemporary electric vehicles have lithium-ion batteries—the same type to power your phone. These batteries are effective, strong, and durable. But they are also vulnerable when it comes to charging and usage. Lithium-ion batteries are more comfortable when working at a charge level of 20 to 80 percent.
A battery undergoes greater stress when charged over long durations at very high charge levels. This stress gradually diminishes the power-holding capacity of the battery. It may lead to decreased driving range and performance in the long run. Of course, this doesn’t happen overnight, but charging habits do make a difference over several years.
According to some reports and studies, continuously charging the EV’s battery beyond 80% is quite harmful and dangerous due to several degradation phenomena. It causes decreased battery lifespan over time, and dissolution of active materials, along with the risk of explosion. In Colorado alone, there are many cases of fire breakouts caused by EV battery explosions. In fact, many firefighters admitted that they find it quite tricky to put out the fire caused by EV lithium-ion batteries.
(Also read: Can you use any charger for your EV?)
Why Avoid Charging Your EV to the Fullest
By this point, you must have understood that charging your EV to 100 percent can erode the battery’s performance. The internal voltage often gets higher when a battery is fully charged. If your battery continuously experiences high voltage, it can speed up the degradation of the battery.
Let’s understand this scenario with the balloon analogy.
Imagine filling a balloon to its full capacity and letting it hang around all day. It will weaken more quickly than a half-full balloon. The same thing happens to EV batteries. Keeping them fully charged all the time puts extra strain on the cells, especially in hot weather.
That’s why most EV manufacturers don’t recommend charging to 100 percent every day unless you really require the additional range. According to a study published in MDPI (Journal of Applied Sciences), limiting an EV’s maximum charge to 50% could increase battery life by 44% to 130%. Geotab, a leading fleet management software company, has found that batteries kept in the 20-80% range showed significantly less “capacity fade” than those charged to 100%.
Understanding the Optimal Daily Charge for Most EVs
Most professionals and car manufacturers recommend that the charging level of the battery should be between 20 and 80 percent for daily driving. This range of charging is quite safe and doesn’t hurt the battery life. Moreover, it ensures sufficient driving distance for normal use.
When you have a short or medium commute to work, you can charge your EV to 70 or 80 percent, which is typically sufficient. Modern EVs have plenty of range, and most people do not use even half of it on a typical day. Most EVs let you set a charge limit on their system or associated mobile app. This feature is really useful to prevent overcharging.
When it Makes Sense to Charge to 100 Percent
Charging to 100 percent in some cases is not bad. You may need it for certain scenarios, like long road trips. In case you are intending to cover a long distance and avoid frequent charging stops, it is a good idea to charge to 100 percent before leaving. Here, the battery will not stay at full charge for long because you will start driving soon after.
The other case is when your EV manufacturer specifically suggests full charging every now and then. Occasional full charges on some vehicles are recommended so the system can better understand the battery level and show a more accurate driving range.
How Often Is “Once in a While”
No universal rule can be applied to all EVs, but there is a general rule that suits the majority of drivers. Charging to 100 percent once or twice a month is usually safe if it is followed by driving soon after.
In case of regular long journeys, you can charge up more frequently. That is okay, as long as the battery does not sit at 100 percent for many hours or days.
The best thing is to stop the habit of filling it up at night when you generally don’t need it.
The Temperature Effect in Charging Decisions
Battery health is dependent on temperature. Lithium-ion batteries are particularly sensitive to high temperatures, especially when they are full. When you are in a hot climate, leaving your EV at 100 percent charge may trigger the wear of its batteries.
To preserve the battery, it is a good idea to park your EV in the shade or in a garage and not charge it to full capacity when it is scorching hot.
Cold weather, on the other hand, comes with its own share of concerns for EV drivers. It temporarily reduces battery efficiency and range, but it does not cause the same long-term damage as heat. Therefore, make sure to park your EV indoors to keep it warmer and pre-heat the car. To protect your EV from cold weather, you can read this guide.
Fast Charging and 100 Percent Charging
Another aspect is fast charging (DC). Fast chargers inject a high amount of power into the battery within a short period of time. However, it generates more heat than slow home charging. It is okay to use fast chargers every now and then, but using them daily, particularly to get to 100 percent, can impact the battery performance.
Which EV Manufacturers Recommend in Reality?
Tesla
To achieve the longest possible battery life, Tesla suggests that the owners should charge their cars up to approximately 80-90 percent to use them every day.
(Also Read: Tesla Charging Precautions)
Nissan
Nissan, through its best-selling LEAF model, has the same piece of advice to offer. The Nissan LEAF comes with a specific timer to let you set the charging limit for daily activities.
Chevrolet
Chevrolet recommends Bolt EV owners to use the “Hilltop Reserve” option (in earlier models) or the “Target Charge Level” option (in later models), which keeps the charging under 88%. Chevrolet also recommends 100% charging occasionally, although continuous low levels of charge are advisable.
BMW
In the case of EV models by BMW, it is recommended to set the charge to approximately 85 percent to drive every day.
Audi
Audi recommends 80% charging for daily use.
Ford
Ford recommends charging to 90 percent for daily use.
Final Thoughts
Charging your EV to 100 percent is totally fine in scenarios like long road trips. Otherwise, keep the charge level between 70% and 80% to maintain the health of your battery. Plus, it is always useful to read the user manual of your EV model, as some models may have specific charging requirements.
If you want to know more about safe charging habits as well as boost the charging efficiency, reach out to us at EZ EV Electric. We are reliable EV charger installers in Colorado and serve the local communities with tailored solutions. Contact us now.
