The most expensive single part of an electric car is the battery pack. Of course, this can be a concern for new EV owners when it comes to longevity, maintenance, and reliability. But, have no fear. EV batteries are designed to be long-lasting and to withstand a lot of use.
EV Battery Packs vs ICE Vehicle Batteries
First, let’s clarify what an EV’s primary battery pack does versus your typical internal combustion engine (ICE) vehicle’s 12-volt battery, as they serve fundamentally different purposes. An EV’s battery pack, often referred to as a high voltage (HV) battery, is designed to store and release significant amounts of energy, which then causes the rotation of the vehicle’s electric motor, propelling the car forward. Electric car battery packs are made up of thousands of individual lithium-ion cells.
In this Tesla Model Y battery pack display, you can see the individual cells used in each pack.
On the other hand, an ICE vehicle’s battery, sometimes called a “starter battery,” provides short, high-energy bursts to start the engine. They do not propel the vehicle in any way. Once the vehicle is running, the alternator typically provides all of the necessary electricity. These small, usually lead-acid-based 12-volt batteries can power electronics like the lights when the car isn’t running. If you own a hybrid or plug-in hybrid (PHEV), they have both types of batteries.
EVs Have 12-Volt Batteries Too
Keep in mind that electric cars have 12-volt batteries as well. They also power auxiliary systems such as the lights, the infotainment system, and ensure you can operate critical components like the hazard lights if the HV battery dies.
Just like with your ICE vehicle, an EV’s 12-volt battery can operate the lights and other electronics.
How Long Do EV Batteries Last?
Most EV models are so new that there’s not a significant amount of high-mileage data available, but the generally accepted EV battery pack life is between 100,000-200,000 miles or 10-20 years. The good news is that the federal government mandates that car makers must provide a minimum of 8-year or 100,000-mile warranty coverage. According to ownership data collected from 15,000 electric cars, only 1.5% have needed a battery replacement (excluding recalls).
Tesla’s battery warranty often goes above what the federal government requires.
Though it wasn’t mentioned specifically, it could be assumed at least a good amount of these repairs were completed under warranty. Electric car battery packs are built to last. Everything from how they are packaged, to advanced thermal management systems, and sophisticated software is there to ensure that the car’s pack stays healthy and within ideal operating temperatures at all times.
Battery Degradation
Something you need to keep in mind is that batteries degrade over time, regardless of how much you might baby them. It’s just a fact of life with lithium-ion cells and that’s the same story with your laptop or cell phone batteries. One study of 6,000 various EV models found that the average capacity lost per year to be 1.8%. Another study of 15,000 electric cars found the average battery capacity retention to be 90% after 100,000 miles of use.
In essence, battery degradation is unlikely to be noticeable for many years of ownership.
Charging Habits Can Make Things Worse
While you can’t stop battery degradation altogether, there are certainly some behaviors and habits that can make your vehicle’s pack lose capacity at a faster than average rate.
Your daily charging habits will have the biggest impact on your EV battery’s health long-term.
Frequently Charging Above 80%
Lithium-ion batteries do not like to be in a high state of charge for very long. Charging your car up to 100% capacity and letting it sit there overnight on a regular basis may cause the individual cells to stress from the heat, create lithium plating on the anode, or cause the growth of dendrites, all of which you don’t want to happen. Essentially these things will reduce usable capacity over time.
You can limit your EV’s charge within the in-car software or the mobile app.
While you’ll find that recommended maximum charge limits may vary, the generally accepted practice is to keep your vehicle at a maximum of 80% full on a daily basis, which leaves plenty of room for the pack to “breathe.” One exception is if your vehicle has a lithium iron phosphate (known as “LFP”) battery chemistry, as this pack type is quite different.
Tesla uses an LFP battery pack in some of its models.
If you’re going on a road trip and really want to charge to 90-100%, that’s fine. You can do so, just make sure you drive the vehicle as soon as it reaches this state of charge to reduce the stress on the pack. Personally, I’ve never found that I have needed 100% of my range, so I always keep the maximum charge limit at 95% for road trips when necessary, just to help reduce premature wear.
I’ve taken EVs on many road trips and have never needed to charge them to 100%.
Tip: If you’re going on a vacation and can leave your car plugged in, set the charge limit lower (but not too low) such as 50% or 60% to keep the battery at an optimal level while you are gone.
Frequently Discharging Below 20%
Opposite of too much energy, a consistently low state of charge can strain your batteries to provide the power needed to sustain the operation of your vehicle. This can cause the voltage to become unstable which may end up damaging the cells themselves. Again, a very low charge level isn’t a concern when it happens infrequently, but discharging the pack below 20% every single day isn’t ideal. Constant deep discharges below 5% are even riskier.
You don’t want to run your electric car’s battery down too low for too long, either.
What Are Replacement Costs?
The total cost will depend primarily upon how large of a battery pack your car has. A good rule of thumb is to expect somewhere in the $8,000-$20,000 range. Closer to the low end if you have a small pack around 60 kilowatt-hours (kWh) and the high end for a 100 kWh+ pack. Again, there is somewhat limited data on this, as replacing a battery pack outside of warranty is very unlikely.
Seriously, Don’t Worry About the Battery
While some numbers may make you think twice about EV ownership, don’t sweat it too much. Electric car battery replacements aren’t the norm and battery management software is getting very advanced. The loss in usable capacity due to degradation will also be so small and gradual that most will never notice until many years into ownership, if at all.
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