The batteries are all fixed into a permanent package. The Tesla battery system is described here.

Whether this a "kludge," or highly creative engineering using existing tech, is arguable. Certainly if the company had started from scratch to develop new lithium-ion battery systems, we'd still be waiting for Tesla cars five years from now.

The big sticking point in electric cars has always been batteries. This has become more focused in recent years--it's becoming apparent that the company that licks the remaining problems in lithium-ion tech will rule the roost, and several outfits are busting away on it.

Theoretical results would include long ranges, and charge times possibly measured in minutes.