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What do you do when your e-car battery wears out? Survey finds they almost never do

tesla battery power degratdation model s p  d
Andy Boxall/Digital Trends

We’re breaking new ground with the fleets of electric-powered and autonomous cars coming our way in the next 2 to 10 years. Range anxiety — how far can I go on a charge? — arises when considering all-electric cars versus gas and diesel power, but that concern will be answered with higher-capacity batteries and more widely dispersed charging stations.

Another interesting question is about the lithium-ion batteries in electrical vehicles. How long will they last? Sure, they’re rechargeable, but so are laptop lithium-ion batteries, and we know they degrade and eventually wear out. So what about electric car batteries? The way they’re built or tucked into vehicle chassis, switching them for new ones sounds like a considerable service effort and an even more considerable expense.

Tesla Motors has a reassuring answer to the question of e-car battery longevity, according to Electrek. All Tesla’s come with an 8-year, transferable, unlimited warranty on the batteries and the drive train. It’s called the Infinite Mile Warranty. The catch is that “the loss of battery energy or power over time due to normal battery usage is not covered under this warranty.” So the question still remains, what can we expect for power?

Related: More Tesla Model S versions on the way: 75kWh battery is up next

An electric vehicle advocacy group called Plug In America surveyed Tesla Model S owners. The survey used data from 495 vehicles that traveled 12,588,649 miles in total, and 17,214 miles per year on average. You can access the full report on the survey website, but the summary is promising. The survey showed that on average the Model S lost about 5 percent of their power in the first 50,000 miles and that the degradation then slowed. Tesla’s Model S hasn’t been available longer than four years, but among several with 100,000-plus miles, the battery pack degradation was less than 8 percent.

With all the power in reserve in Tesla models, those figures sound pretty good, but the company is going further. Tesla is partnering with Dalhousie University in Halifax, Nova Scotia, to find ways to improve lithium-ion battery cell longevity. Electrek noted that CEO Elon Musk has stated Tesla has a battery back in its lab with more than 500,000 simulated miles still operating at over 80 percent of its original capacity.