Take a look at a major airport. They could average a hundred rental cars arriving, with peaks into the hundreds. Even assuming every can arrives at a half-charge, the power requirements would be immense. At 50kwH per car, charging up 100 cars every hour would require, at an absolute minimum, a 5000kw/5mW connection.
The rental co really needs to provide reasonable charged cars, and so long as charging infrastructure is dicey (especially with hotels in the mix) they could provide peace of mind to their customers by providing a known charging spot.
Put it wherever, I'm not Hertz, the airport is not Hertz's customer, but I would have a pretty strong bet that Hertz's customers would expect this sort of thing.
Do you have any reason to believe car rental companies maintain onsite fuel stations? Have you ever seen one? Why don’t they let customers use it?
There are already gas stations near airports. If a car needs gas they pay someone to drive it there and fill it up. That’s the source of your inflated prices.
Plus, often when I rent a car, it isn't full. I'm sure they still charge the person "to fill the tank," but they don't actually fill it, so the total they'd have to store on-site is even less than if they were actually filling the cars.
I also assumed they had somewhere to store siphoned fuel, because every car I've ever driven has at least a gallon before the needle moves off of "F," but rental cars drop below F immediately. I've always assumed they were siphoning out a gallon or more any time someone did return the car all the way full.
The power requirements were not drawn up with the car rental agency in mind. Maybe you can get the airport to cooperate and ask the utility to expand capacity - how many years of planning do you think that takes?
They have the added challenge of people dropping off cars at a different place from where they started, so they can’t necessarily say “we’re going to start with EVs at our new facilities where we can design that capacity from the start.” They needed fast charging everywhere for this to go smoothly.
How long do cars sit in the lot? Do you need to send cars out at 100% full? Is it good enough to make sure the cars leave the lot with 50-80% full?
They're returned, inspected, cleaned, put in the "outgoing" queue. I suspect having DCFC for just the cleaning area and then 16 or 20 or 24a /240v posts for L2 charging the cars as they sit waiting to be rented would more than suffice.
Other big issues would be around having to have dedicated parking for EVs and also having charging posts sticking out of the ground all over.
50kWh is not the charger, half the battery capacity for the cars (as decided by GP).
And 50kW would not be a huge charger, or even a large one, it's the bottom end of DC charging.
> I suspect having DCFC for just the cleaning area and then 16 or 20 or 24a /240v posts for L2 charging the cars as they sit waiting to be rented would more than suffice.
Aside from not being very efficient, 24@240 is not really a thing that's used. 32@240 is relatively standard but it's 7.2kW and generally considered a residential AC charger, acceptable when 3-phase is not available (or too expensive). It needs 7 hours to half-charge a 100kWh battery.
A car rental setup would benefit from having a couple big DCFC setups where cars are inspected / cleaned.
EVs charge fast if the battery is empty (and warm) -- so the car comes in, is inspected and cleaned and put on a fast charger, and in 20 minutes will get to ~50% charge (regardless of battery size).
As far as "not efficient" or "nobody uses" well, 240 (or 208 if you're in a commercial setup with 2 legs of a 3 phase) is "normal" and a 16a / 20a / 24a AC charger will put reasonable charge on the car while it's just sitting there waiting to be rented again. EV's don't need to be fully charged to be useful so you don't need to put the battery back to 100% before sending it out again.
"your car is at 60% charge and has 180 miles of range right now; your car's nav will tell you where to charge if you need more range to get to where you're going. We'll bill for the power if you bring it back to us at less that 60% full. Have a nice day!"
I'm not sure what the turnover is for a rental lot -- I suspect "it depends" but I suspect it's not unusual to have cars on the lot for 6-12 hours before they're sent out again.
IMO As long as the car has 60% or better charge (or, 150-180 miles of range) it's "good to go". At least for most "airport rental in a major metro area" situation.
As far as charging efficiency -- anything charging at 240/208v is "good enough" -- the differences between 16a or 20a or 24a or whatever are minor relative to the bump from 120v to 240v.
(I had a friend joining me on a trip a number of years back. We wanted to add them to the contract once they arrived. I had to patiently explain that we could do it with a company that also had an off-airport location but we couldn't drop by the car rental center at the airport. I've had other experiences with how car rental companies really don't have good mechanisms to change things once you've signed and initialed the contract.)