Comparing battery life of top electric car brands

If you’re looking to lower your carbon footprint (and your gasoline bills), electric vehicles (EVs) are a great option. Powered by electric motors rather than internal combustion engines, EVs allow drivers to use electricity (which can be generated via renewable energy) as fuel. While EVs were previously regarded as unreliable for long-range driving and far too expensive for the average driver, the expansion of EV charging stations, energy storage systems, home chargers, and EV incentives have all boosted EV adoption. So how long do battery cells actually last? 

Electric car battery technology is designed for extended life – some batteries even outlast the vehicle itself and power a second life through battery recycling! But, as with any other rechargeable battery, it will still degrade over time and even with fast charging stations becoming more widely available, you’ll want to make sure your battery will provide enough range. So, to protect drivers, EV manufacturers offer warranties on their batteries. As an EV driver, it’s important to know what your battery warranty covers and how you can prevent your battery pack from losing capacity.

Your EV's battery life can be negatively impacted in several ways:

1. High temperatures: operating an EV in high temperatures can degrade the battery. Additionally, parking your EV in the sun for long periods of time can have similar degradation effects.

2. Overcharging/high voltages: charging an EV battery pack beyond its voltage limit can cause internal resistance in the battery. Most batteries have built-in battery management systems (BMS), so overcharging is rarely an issue, but it is good practice not to charge your battery right up to 100 percent.

3. Deep discharges/low voltages: draining most of your battery’s capacity frequently, or completely draining an EV battery, reduces battery capacity over time.

4. High discharges or charge current: pulling too much current from your battery over a certain amount of time can have detrimental effects on its life. When possible, avoid aggressive driving patterns that might pull high amounts of current from your battery all at once.

All EV batteries will degrade over time, but avoiding the above situations can help you maximize your EV battery life!

Automakers offer battery warranties to protect EV drivers. These warranties usually cover a certain amount of time and a certain number of miles driven, and end when the threshold of one or the other is met. The warranty typically guarantees that the battery won’t degrade past a certain percentage of the original charge capacity during the warranty term. 

For example, let’s say a manufacturer offers a five-year/50,000-mile warranty at a percentage guarantee of 80 percent. If your full-charge battery capacity ever drops below 80 percent of the original battery capacity before five years of ownership or 50,000 miles are driven (whichever comes first), you can receive a new battery or get yours serviced for free. In this scenario, if your original battery capacity is 100 miles, this warranty guarantees you will get at least 80 miles from a full charge after five years or 50,000 miles of driving.

This formula for battery warranties is not universal, so it’s important to examine your individual warranty closely to make sure you know what protection you have. Here are some battery warranties for several top EVs available on the market:

A few notes to keep in mind:

• Lithium-ion batteries, nickel-metal hydride, ultracapacitors, and lead-acid batteries are the main types of electric vehicle batteries. Lithium-ion cells have the highest energy density (meaning they store more kilowatt-hours in proportion to their weight and size) and are the most common type in EV modules. 

• The Nissan Leaf has a percentage guarantee of approximately 75 percent because they guarantee in “segments” (their own measurement for battery life). A full Leaf battery has 12 bars, and the included battery warranty guarantees 9 bars of charge.

• The Toyota Prius is a hybrid electric vehicle and still runs partially on gasoline. 

How long electric car batteries last depends on the range of the vehicle. Electric vehicle battery warranties are most applicable for shorter-range vehicles because a regular commute might only drain a small percentage of a long-range battery, but that same commute might constitute a “deep discharge” on a lower-capacity battery, which degrades battery life more significantly over time.

For example, the Nissan Leaf has a range of 149 miles brand new, while the Tesla Model S has a range of 405 miles. Driving 50 miles on one charge would use about 34 percent of the Leaf’s battery capacity, and only about 12 percent of the Tesla’s capacity. Thus, commuting on the Leaf represents a much deeper discharge than a higher-capacity car like a Tesla.

Deeper discharges lead to more rapid battery degradation, so it’s important to make sure the warranty you receive will cover your driving habits, especially for those who want a lower-range vehicle. For more information about EV range, check out EnergySage’s overview of ranges for popular electric cars.

Whether you are purchasing a plug-in hybrid car or an all-electric EV, it is essential to talk with the manufacturer and verify the warranty and understand the expected lifespan of your battery. Electric vehicle batteries are expensive, so you’ll want to confirm the specifics in the rare case that your vehicle’s battery does end up degrading rapidly.