The battery capacity of the original Tesla Roadster was 53 kWh.
The original Roadster, produced from 2008 to 2012, used a 53 kWh lithium-ion battery pack. Tesla called this battery assembly the Energy Storage System, or ESS. It contained thousands of cylindrical 18650-format lithium-ion cells arranged into interconnected sheets and bricks.
The Roadster was historically important because it was the first highway-legal production electric car to use lithium-ion cells and the first production electric car to offer more than 200 miles of range on a charge. Its EPA-rated range was about 244 miles, an impressive figure for the late 2000s.
The 53 kWh figure can be confused with later replacement packs and upgrades. In 2016, Tesla began offering an upgrade that increased the pack’s nominal capacity from 53 kWh to 80 kWh. Battery capacity also differs from usable energy and from charging losses, so real-world energy taken from the wall can exceed the pack’s stated capacity. The Roadster’s battery technology helped establish the engineering foundation for Tesla’s later Model S and Model 3 programs.