Guys, again...I don't care whether you like battery swapping or not. There are lots of threads to discuss that. Let's not fill this one with discussion about why it's not a good solution or why you wouldn't use it. It's coming, whether you like it or not. Help me figure out HOW they are going to do it.
In response to some thoughts that have come up so far.
Are Tesla going to have both 60kWh and 85kWh batteries availabe for swapping, and if not, will swapping be only for the 85kWh batteries? Will buyers of the 60kWh cars feel left out and cheated? Or will they also be able to swap (the 60kWh against an 85kWh battery) and if so at what cost and terms (how long can they keep the 85kWh in the car)?
Great question. Having to stock both 85 and 60kWh batteries seems like it would also make the cost of the station balloon. Perhaps 85s could be software limited to 60kWh. We know they already developed software to do this kind of thing (with the "40kWh" packs). I think this would be cheaper than having enough of both packs on hand.
It simplifies the operations. But storing the battery is a solvable problem. RedBox routinely takes reservations for movies and holds them until you come to pick them up. In process terms its a trivial task to engineer. It just requires additional resources be devoted to the swap station infrastructure and a larger inventory for the batteries.
I think your RedBox analogy is a good one, but you glossed over a lot of detail and thereby drew the wrong conclusion. Yes, you can reserve a movie, and that's exactly what I said you should be able to do with a battery. The thing is, RedBox allows you to then return that movie to any RedBox. You don't have to bring it back to the same one. Also, you only have a limited time to pick up your rented movie, before it goes back in the available pool and you get charged anyway. The whole system is built on the assumption that any copy of Iron Man 3 is as good as any other.
I don't see how this supports the idea of storing your battery for you to come back and pick up at all. It sounds a lot more like the analogy supports the description in my OP. We need to be able to make the same assumption with battery swapping to make it work.
It simply requires an inventory of batteries entirely separate from "owner" packs. I don't think the numbers will explode, just that the battery swap "network" must be independent of owner packs.
Of course it does, do some math with me. If you have a swap station that gets one visitor per hour on average. And, the average time it takes for a owner to come back to get their battery is 2 days (call it a weekend trip), then how many extra batteries do you need on hand to handle the average case?
2d * 24h = 48 packs
You'd need to have 48 batteries. Right? By the time you get your first "swapped" battery back and can give it to a second person, you've had 47 other owners stop by for a battery. Actually, you need 49 because you still need to supercharge that battery you just got back before you can give it to someone else and/or you need one to do the very first swap.
Now, what if you could swap a battery, charge the battery you just got, then give it to the next owner that shows up for a swap? How many batteries do you need stock the station with?
One battery. You need to give a battery to the first person that shows up, but then you can charge their battery in the hour before the next owner needs a swap.
Now, this is only the average case, and uses completely arbitrary parameters. Obviously, you need more than this in both cases to be able to deal with peak travel times. Varying the average time between swaps and average time before an owner returns to claim their battery changes the number of batteries you need on hand, but the relationship is really the same. Storing batteries for owners makes the whole system prohibitively expensive.
Anyway, if they were to do it, the only workable way is leased, imho. That avoids the inventory and ownership issues.
You may be right about this.
In another thread on this topic, I proposed a "Road Trip" solution:
1) Drive to the furthest Swap Station you can reach on your battery's full charge.
2) Swap batteries. Yours gets tagged, charged, and put on a shelf
3) Drive to the next charging station and swap again.
4) Reach your destination. Charge overnight/whatever.
5) Drive home, stopping at Swap Stations as needed.
6) Stop at the first Swap Station and get your fully charged original battery back.
7) Drive home.
Your battery is used only in your car, so no worries about its condition.
It doesn't scale. These stations will need to be warehouses one day if Tesla wants to sell a million cars a year. They'll need so many more batteries than cars. I just can't make the math work in a way that keeps Tesla in business. =)
Note the main appeal to swapping is not so much quicker stops as it is the ability to buy a smaller battery for your everyday use and then swap for big batteries during road trips. IMHO, anyway.
If this is what they are going for then I think just switching at a service center makes the most sense. It seems to me that they are going to do actual swapping stations, which wouldn't be the right choice if this is all they wanted to accomplish.
I suppose one question is what about trips that don't end up on the same route. Ie I use a super charger and then land at a swapping station, but that station is 500 miles out of my way for return trip cause I'm coming home a different way. Also if they get rid of superchargers then I won't be happy that I paid for the install, and why would they have spent the money to equip all cars with it? If they super charge the battery while its in storage than there is no need for the super charger equip in the car... So if they knew it was coming it seems a waste of resources to install it in every car....
Read my OP. The theory is that Supercharging is still the most common way to do intercity travel. Also it is the fallback during peak times when there simply aren't enough batteries at a station.
(16 gal. -> 12.5 mpg)
