A lab result from 2019
In September 2019, a team at Dalhousie University in Canada, funded in part by Tesla Canada, published cycling data in the Journal of The Electrochemical Society, a peer reviewed journal, meaning other scientists checked the study before it printed. A cell chemistry is the mix of materials inside a battery that sets how much energy it can hold and how long it lasts. The team ran a lithium ion cell chemistry through repeated charge and discharge cycles, a test called cycling, and kept it at 20 degrees Celsius. That cell should power an electric vehicle for over 1,600,000 kilometers, over 1,000,000 miles, and last at least 20 years in grid energy storage, batteries connected to the power grid rather than to a car.
Each test ran at the C over 3 rate, 100% depth of discharge, between 3.0 and 4.3 volts.
Show the numbers
| Tested at 20 degrees Celsius | 4,000 |
| Tested at 40 degrees Celsius | 3,700 |
| Tested at 55 degrees Celsius | 2,500 |
A company promise, a year later
In June 2020, Zeng Yuqun, chairman of CATL, a Chinese battery maker, told Reuters his company was ready to build a battery lasting 16 years and 2,000,000 kilometers, 1.24 million miles, for Tesla, if Tesla placed an order. The promise described a different cell from a different company, made a year after the Dalhousie study, and it does not confirm that earlier number. It is CATL saying it could build something close to it.
If someone places an order, we are ready to produce,
Zeng Yuqun, chairman of CATL. Source 2.
What batteries are doing on real roads
A Morgan Stanley research note from January 2026, reported by Electrek, tested 12 electric vehicles and 100 sample batteries across 4 cities in China. After 2,000,000 kilometers of use, CATL cells still delivered about 400 kilometers of range. Rival cells retained about 350 kilometers or less over the same distance. At a separate site, the Zhangbei National Wind Solar Storage Demonstration Project, a grid storage installation rather than a moving car, CATL batteries are the only ones among 4 suppliers never replaced, retaining over 90% of capacity after 14 years.
Rival cells retained 350 kilometers or less. Figures come from a Morgan Stanley test of 12 vehicles and 100 sample batteries across 4 Chinese cities, reported by source 3.
Show the numbers
| CATL cells | 400 |
| Rival cells | 350 |
The warranty has not moved
The Department of Energy states that many manufacturers still offer only an 8 year, 100,000 mile warranty on an electric vehicle battery. A warranty is a promise from the manufacturer to repair or replace the battery if it fails before the stated years or miles, so a buyer is covered only up to that number, not beyond it. That 100,000 mile figure is about 10% of the 1,000,000 mile figure the 2019 study projected, a comparison this article makes because neither source states it. The Environmental Protection Agency cites a 2025 study of about 15,000 vehicles that found 97.5% still running their original battery outside major recalls, and the annual failure rate fell from 7.5% in cars built in 2011 to under 1% in cars built since 2016. The batteries are not obviously the limit. The number printed in the warranty book is.
The lab projection is source 1. The warranty figure is source 5. The two describe different things, a laboratory result and a market warranty term, not the same fact measured twice.
Show the numbers
| Lab projection 2019 | 1,000,000 |
| Standard warranty today | 100,000 |