thecarchik writes "In contrast to every other automaker, which use specialized large format Li-Ion cells, Tesla's battery pack is made up of thousands of inexpensive commodity cells similar to those found in laptops. Unlike automotive cells, these cells are produced in the billions, subject to the fierce competitive pressures that are a signature characteristic of the computer and consumer electronics industries.
Even including the overhead of the pack enclosure, connections between cells in modules (and modules in the pack), sensors, and circuitry, Tesla likely has lower pack costs than any other maker of plug-in electric cars. But even without the simplified design Tesla created, the standard Panasonic NCR18650A 3100mAh cells that Tesla uses probably don't come close to costing it $400 per kWh that the media has estimated.
It's not unreasonable to think that less advanced, but high-quality 3100mAh cells are now indeed selling for $2 per cell (or $180/kWh). If the cheaper Tesla-designed, cap saves even a dime per cell, that would cut the price to around $170 per kWh."