A battery pack has between 500 and 1000 charge cycles, so each swap on the $20K pack will recover you $20-40 in depreciation. It's the main cost of using an electric car.

So then, the business challenge becomes to extract more value from a pack than a car owner can. There are many opportunities to do that:

- much improved inventory management, buy in bulk, monitor and adjust charging parameters etc. to prolong battery life based on observed performance of the specific battery type.

- this allows you to optimize battery purchase and chemistry to minimize overall cost even at the risk of a reduced lifetime

- centralized recharge gives you economies of scale to purchase cheap electricity during the night and enter all sorts of contracts where you can earn money by acting as a last-resort supplier at peak times, without actually using significant charge cycles on your inventory.

- the same economy of scale is passed down to customers who won't be bothered to install high power fast charge circuits, or are simply unable to.

- differential pricing based on customer needs, for example, new, top performance packs for home users and degraded packs with lower peak current for less sensitive customers, taxis and commercial fleets etc.

- batteries depreciate even when they sit charged; a modular system will allow customers to keep (and pay rent for) a single or low capacity unit on a regular basis for city use and opt for full capacity when they really need the extra range.