Assuming the batteries are not just discarded when swapped, you'd end up charging them, right? If a stall can change 1 battery every 1.5 minutes, then it needs something like 60 batteries available, total.
Take one out, start it charging on a super charger. 60 minutes later it's ready to be used.
Once the cache of pre-charged batteries is empty, the latency is the charge time (~60 mins) and the throughput is the charge time multiplied by the number of chargers they have. So when they run out of pre-charged batteries, have 10 chargers at the station, and you're the 11th in line, you get to wait for 2 hours. "All you have to decide is fast or free, and how to cut in line" ;)
I am just theorizing here, but If i were designing this system it wouldn't work like that.
When a battery comes out of a car, it goes on a charger(underground, or wherever). Each charging station starts with 42 batteries(2 extra for good measure) and each spot that a battery sits in wait is a charging station of its own. At minute 0 a battery goes on the charger. After 40 battery changes, one every 90 seconds, an hour has gone by. At this moment the first battery we put on the charger is full, and we have 39 more charging batteries each finishing their charge at 90 seccond intervals in the same order they went in.
In this way, we never run out of batteries.
Of course first they have to change the system to leased batteries so they dont have to give do the whole 'come back for _your_ battery' thing.
The requirement to return and unswap your battery does put quite a crimp on the ability to make trips that aren't strictly plotted out, with no side trips. As this is being promoted for long trips such as vacations, the batteries might need to be shelved for weeks at a time before the user returns. Considering more than a trivial number of users and the storage area required would be vast.
You are correct that this only really would work with leased batteries, but this would require owning up to the actual wholesale manufacturing costs of the batteries, depreciated across the number of miles before the battery is no longer practically usable. Tesla stockholders tend to get upset and confrontational when these numbers are discussed, despite that they are easy to determine since the cost of the Panasonic NCR18650A cell, the number used per Tesla (6831), and the lifespan of the cell, are all known.
Yea, I though the same thing. But I also remember the gas rationing in the 70s where you were only allowed to buy gas on alternate days (based on the last digit of your license plate) which could be the reality again if we continue our current rate of consumption.
And I really don't get why people stand in line at a Costco for 20 minutes to save 15c gallon. $3 savings for 20 minutes "work"? Is their time really that cheap?
Take one out, start it charging on a super charger. 60 minutes later it's ready to be used.