BMW i3: Light Weight Means Less Energy Storage Needed

The Power Electronics & Battery System of the i3's Drive System

The previous post here showed a video about CFRP, the material that will be used in the "Life Cell" of the 2013 BMW i3. The picture above is part of the other component of the cars unique LifeDrive architecture, the drive system. This is the energy storage and power electronics the car will employ. Suprisingly, it may only use a 16 kWh battery pack, exactly half the size of the pack in the upcoming BMW ActiveE, yet give the vehicle roughly the same range of the larger, heavier and less efficient ActiveE. However it is possible that the 16 kWh is the "usable" amount of energy which would mean the pack would be around 20 kWh. BMW hasn't announced the actual size, so this is really speculation at this point.

To put that accomplishment in even better perspective, the battery is only about 45% of the size of the battery pack currently in the MINI-E's yet the car is bigger, has two more seats, much more storage space and is expected to offer the same driving range.


The batteries used will be the same that are in the BMW ActiveE, which will launch as a trial lease program this fall. They are newly developed Lithium-ion cells which will be using a nickel-manganese-cobalt chemistry made by SB-Limotive. SB-Limotive is a joint venture of Korean conglomerate Samsung and German parts giant Bosch. The ActiveE will use 192 cells in 25 modules in three separate battery blocks as opposed the the picture above where the i3's batteries are all located in one enclosure, a result of the car being a purpose-built EV and not a retrofitted ICE platform like the ActiveE. It's been rumored the i3 may use only 96 cells, in 48 smaller modules(only 2 cells per module) packed in rows under the Life Cell driving compartment and be thermally conditioned.

The end result means two main things. The battery is usually the most expensive part of an EV, and since the battery pack will be half the size of the ActiveE, it will cost significantly less to manufacturer, helping to keep the selling price of the i3 to a reasonable point. Secondly, less batteries means less weight and helps to further increase efficiency.

Complete Battery & Drive System of the 2013 BMW i3

Of course, none of this information has been "officially" released by BMW so it is speculation on my part. However, since it has been "reported" and "rumored" by many different media outlets I think it's safe to assume it is mostly accurate. The only question I have is whether the 16 kWh is the total pack or the usable amount which is usually about 80% of the packs total energy storage capacity.