> Any idea why swapping didn't pan out for Tesla?

~~Two~~ Three things:

1. California changed the rules shortly after Tesla demonstrated their swap station, which practically eliminated the tax credit for battery swap (at the behest of lobbyists for Toyota, who were backing Hydrogen Fuel Cell technology). Specifically, the credit would be prorated by the percent of “fast refueling” sessions a car did, so EVs primarily charged at home received almost nothing while HFCV got the full credit. Building swap capability adds complexity to the car (think about all the fluid connections), which isn’t worth it without credits.

2. It was also around this time that a Model S ran over an anvil (or something) which punctured the pack and started a fire. In response, Tesla added an aluminum battery shield, which further complexifies swapping and was probably the final nail in the coffin.

3. The logistics of storing your very expensive battery (so you could get it back later) basically make the system unworkable. When the Tesla swap station at Harris Ranch (you can still see the former building, next to Harris BBQ, which currently houses the restrooms) was operational, you had to make a reservation some hours in advance so that Tesla could have a pack ready and be ready to take your pack to/from storage.

3a. Gresham’s Law. Without eventually returning the pack to the original owner, there is an adverse selection problem: people with very weak packs will gladly roll the dice on a swap, but those with brand new packs are reluctant. So the average quality of packs in the swap network will quickly decline creating a death spiral.

3b. You could probably fix 3a by leasing the battery (or selling battery-as-a-service) but car buyers mostly don’t like that, especially back in 2013.