The first question most electric car shoppers ask when they’re considering an EV is, “How far can I drive?” Certainly, in the top five questions, though, is “How long do electric car batteries last?” It’s an important question, as an electric vehicle’s battery pack is the most expensive single component of an EV.

Buyers of gas-powered cars don’t typically ask, “How long will the engine last?” But the electric car industry is still in its infancy, and most shoppers come with long lists of questions before they’re convinced that an electric car is the right car for them.

Unfortunately, there’s no easy answer to the question of electric vehicle battery life. According to the National Renewable Energy Laboratory, though, today’s batteries may last 12 to 15 years in moderate climates. That means they’ll potentially outlive the cars they’re installed in. Many experts peg the lifespan of an EV battery at between 100,000 and 200,000 miles.

If your EV’s battery fails before that, it will likely be covered by the manufacturer’s warranty. The U.S. government mandates at least eight years or 100,000 miles of battery coverage, though some automakers give you more, and some states require longer coverage.

The Basics of Batteries
Today’s electric cars are propelled by between one and four electric motors, depending on the model. Those motors are fed with electricity stored in large, heavy lithium-ion (Li-ION) battery packs, which are usually installed under the cabin floor of an EV. The batteries are recharged by external power sources, ranging from household power outlets to public DC fast-charging stations.

More like the batteries in your cell phone than the ones you’ll find in gasoline-powered vehicles, lithium-ion batteries have a high energy density, meaning they’ll hold more energy per pound than other battery types. They don’t require maintenance like other batteries, and they provide a somewhat steady level of power, regardless of how much of a charge they contain.

Lithium-ion batteries are also costly to produce, with raw material supply chains that span the globe. The mining and refinement of materials used in lithium-ion batteries are performed in some countries with problematic human rights, environmental and political track records.

Read more: How Long Do Electric Car Batteries Last?