Solid-state Mercedes EQS drives 749 miles without charging stop

A Mercedes-Benz EQS fitted with a prototype solid-state battery has been driven 749 miles without stopping to recharge, marking a milestone in the development of the technology.

Mercedes engineers drove the modified saloon from the firm’s home town of Stuttgart, Germany, to Malmö, Sweden. It claims to have finished the trip with 85 miles of range left in reserve.

Although the route between the two cities would typically measure around 630 miles in length, the engineers plotted an alternate course accounting for the landscape and traffic conditions, while avoiding ferry crossings. That extended the drive by more than 100 miles.

The car’s solid-state battery uses cells from US firm Factorial Energy while the pack was designed in collaboration with Mercedes’ F1 base in Brixworth, Northamptonshire. Its weight and footprint are said to be “comparable” to a standard EQS’s lithium-ion pack – which yields up to 481 miles of range – but its energy capacity is said to be improved by 25%. 

The battery pack uses a floating cell case with pneumatic actuators that help to manage the expansion and contraction of the cells in operation, to improve their stability and longevity.

Mercedes had previously expected the new pack to improve the car’s range to around 620 miles.

Chief technology officer Markus Schäfer hailed the technology as a “gamechanger”, saying the successful test drive shows how it can deliver “a new level of range and comfort”. 

Schäfer added that Mercedes is aiming to bring solid-state batteries – which have long been considered a major breakthrough for electric cars, but which have faced decades of delays – to market this decade.

That matches the timeline quoted by the rival Volkswagen Group, which has unveiled its solid-state prototype at the Munich motor show. Rather than testing the technology in cars, however, it has opted to use a motorbike built by Audi-owned brand Ducati.