BMW is introducing a new generation of battery technology, developed internally, to be unveiled in the “NEUE KLASSE” electric vehicles in the 2025 timeframe. The cylindrical cells are a departure from the prismatic battery format BMW has previously used. The batteries will be built in two heights, 46mm by 95mm (4695) and 46mm by 120 mm (46120).
Cylindrical batteries offer several advantages over prismatic batteries that BMW will take advantage of. By adapting the 46 mm diameter they’ve landed in the current ‘sweet spot’ for cylindrical batteries. In addition BMW will be relying on an 800 volt architecture, this allows for significantly faster recharging from a 10% to 80% capacity of the battery system. BMW predicts a 30% reduction in charging times.
The 800v architecture allows for less total heat, thinner wiring – less cost and weight (ever wonder why big box stores run their lighting at 480 VAC?), faster recharging, and better range. Adaptation of the 800v architecture is critical. And 800v level 3 chargers will become standard soon.
Further, given the new chemistry the cells will use less cobalt and more silicon, increasing energy density and pushing range up by 30%. And, thanks to the new chemistry and the use of cylinders for the battery form, the cost of producing the batteries is reduced by 50%. The Gen6 battery technology’s efficiencies in manufacture will reduce CO2 emissions by 60%.
It was the greater energy density available with the sixth generation battery chemistry that allows the cylindrical cell to overcome the packaging advantages of prismatic cells. The cylindrical cell also offers better thermal management than the prismatic packs.
Previous battery pack solutions were optimized in a ‘skateboard’ format – a separate battery pack structure. A substantial physical structure had to be used to enclose the batteries in order to protect them. The cylindrical format offers higher native strength than prismatic cells allowing the pack to incorporated into the open body. This will allow better integration of the battery pack and body – unlike the body above battery pack skateboard design of the BMW i3.
