If there is something that every electric car owner knows and sympathizes with, it is “range anxiety.” This is a terminology that describes the concern of electric vehicle owners that their vehicle will be left with insufficient energy storage before they reach their destination and therefore the car will be stuck on the side of the road or will have to look for a public charging station and waste valuable time on the way to their destination. Range anxiety often causes drivers to charge their battery to the maximum, but could such practice harm the quality of the battery in the long run?
The answer is yes. Charging the battery of an electric vehicle to 100% regularly will shorten the lifespan of your battery. Lithium-based batteries, just like those found in every mobile phone, cannot bear high voltages for long periods, and doing so will accelerate the degradation of your battery. This is doubly true in extreme weather conditions. That’s why most experts in the electric vehicle industry recommend charging to a maximum of 80% of the battery at a time, some will even go so far as to recommend staying within the limits of 60%-70%.
What Happens to the Battery When You Charge it to 100%?
Every electric vehicle owner knows (or should know) that the battery is the most expensive component in his vehicle, and its value can (for some cars) be equal to the cost of the vehicle itself. That is why it is very important to keep the battery lifespan as long as possible. We have no control over some things that affect that lifespan, such as the weather conditions (if you live in a very hot or very cold area), but we do have control over others, such as the (understandable) need to charge the battery to the maximum. That’s why it is worth understanding what happens to the battery when we charge it all the way – and why it is highly recommended to avoid it.
lithium-ion batteries are the current standard for electric cars. When an EV battery is charged to the max (100%) it generates heat internally and raises the temperature of the battery, possibly overheating. The rise in battery temperature affects its performance and safety. Being overcharged in its worst-case scenario can even lead to an explosion. But let’s not go that far: heating the battery by overcharging will, in most cases, simply shorten the life of your lithium-ion batteries and you don’t want that.
EV batteries lose their ability to hold a charge and depreciate over time like any other rechargeable battery. It is important to note that even though the travel distance in electric mode decreases when the battery capacity decreases, the performance of the car is not affected. However, in the long run, it can lead to a decrease in the value of the vehicle so it’s better to give the battery the best care you can, to preserve the battery’s capabilities over time.
EV Manufacturers Made Sure that We Could Not Charge the Battery to the Absolute Max
It goes like this: even if you charge your car to 100% it’s not actually 100%.
Confused? Let me explain.
The car manufacturers have created a system whose purpose is to make sure that the battery cannot be charged to 100 percent or reach a state where it is completely drained. Electric vehicles come with a battery management system that ensures the battery can’t be charged to the maximum or emptied to the minimal limit.
This means that when the dashboard shows that the battery is at 100 percent full, the real truth is that there is an extra five percent buffer of the battery that has not been used and is hidden from us. This is how car manufacturers keep the battery from being damaged over time. If we can’t use it (or know about it) – we can’t destroy it.
The Battery App Lets You Decide Beforehand When to Stop Charging
Most electric cars let the driver call the shots as to how much to recharge the car battery. It can be done through an app or by the car’s touchscreen. The driver can decide to stop charging once the battery has reached the driver’s desired level.
Charging Your EV Battery Rule of Thumb
You should stick with the 20/80 rule of thumb. Meaning, these are your new min/max. Do not charge the battery over 80% and don’t let it reach below 20%.
This can work most time, such as when you use your car for things like kids’ pick-ups or driving to work. If I’m being honest, though, it’s hard to stick to that rule when you plan a long drive.
Let’s take my car for example the MG ZS. Right off the bat, it comes with a rather small range of 300 km / 185 miles. So, charging only 80% will leave me with 240 km/150 miles. Subtracting 20% from this range leaves us with 120 miles. Again, it’s enough for the day-to-day routine but I would like a bigger range when traveling remotely. Given that fast charging stations still take about thirty minutes to charge about 80%, and that’s assuming there’s an available station on your route (in many places the charging network isn’t developed enough to be reliable just yet) a 30-minute delay on the way to your destination can be quite irksome.
Annoying as it may be you really should stick to the 20/80 rule which is supported by the latest research from SEAS: School for Environment and Sustainability at the University of Michigan on the subject of extending the lifetime of lithium-ion batteries.
The research says “minimize the amount of time the battery spends at either 100% or 0% charge. Both extremely high and low “states of charge” stress batteries. Consider using a partial charge that restores the battery to 80% SoC, instead of 100%. If that’s not possible, then unplug the device as soon as it reaches 100%.”
Overnight Charging – It’s O.K. but Not Every Night
Many electric vehicle owners like to charge their vehicles overnight. I can understand why (I do it myself!) You simply charge the battery and forget about it until the next morning. It is incredibly convenient and easy.
I assume that after reading everything written above, you look at this convenience differently and might be afraid of overcharging the battery.
So here’s the thing: it is true that it is not recommended to charge the battery throughout the night, but despite everything written above if you charge the car throughout the night from time to time, there will be no real damage to the car. Just try not to do it night after night regularly, but instead only occasionally and when absolutely necessary.
Conclusion
At the end of the day, your takeaway from this entire article should be the understanding that if your battery isn’t fully charged – it is the best and safest way to preserve the longevity of the battery.
Whether it is 50%, 60%, or 70% – it is advisable to stick to the 20/80 rule and fill the battery to the maximum only when it is decidedly necessary.