Tesla battery swap: Post announcement discussion

[renim]

Tesla just pulled a checkmate on the automotive industry with this demonstration.

I would more describe it as aligning the rooks along a centre column, Rooks working together are strong

lets assume pack swap is 90 seconds, thats 85kwh x 40 swaps per hour ~ 3,400kw 'recharge rate' ~ 34 supercharger slots

lets assume there are 36 supercharger slots, 36 DC chargers (or 18 twin share) but 72 cars turn up at once.

instead of making 2 batches of 36 park and charge,
1 batch can park and charge
1 batch can swap and go
but only 36 DC chargers (or 18 twin share) are now needed to serve 72 cars.
ie
once a supercharger station is large enough, there is synergy between charging and swapping, the swap station can use the DC supercharging infrastructure at non peak times (ie off peak, and shoulder) (and DC supercharging can probably use swap station storage usefully also)

the exact numbers will change ie swap time, charge rate etc, but the principle remains, there is synergy to co-locate the services, but it starts with a large charging station and cheaply doubles it capacity.

For a limited (fixed) amount of money, expanding the largest supercharging stations via PackSwap allows extra money for accelerated rollout (coverage) for the smaller supercharging stations.


Ie
If a 36 slot supercharging station gets an additional 36 car capacity via PackSwap, but that PackSwap capacity incremental cost is about the same as 18 supercharging slots, then Tesla can deploy an additional, smaller 18 supercharging station elsewhere using the savings.

 

[deonb]

If a 36 slot supercharging station gets an additional 36 car capacity via PackSwap, but that PackSwap capacity incremental cost is about the same as 18 supercharging slots, then Tesla can deploy an additional, smaller 18 supercharging station elsewhere using the savings.

You actually only save 1/2 the cost of a SuperCharger since the Solar requirement remains the same.

But you do have a valid overarching point there. There is a point where instead of having additional Chargers at a location, it will be cheaper putting in a Battery Swapper. And I think your numbers are close to the breakeven point.

* 20 chargers + 80 bay solar canopy (so > 3 times an avg. SuperCharger size)
vs.
* 10 chargers + a swapper + 80 bay solar canopy

I bet the above will be in the same ($1m to $1.5) ballpark. It doesn't free up any additional money to build more of them, but it at least breaks even.

 

[Norbert]

OTOH, 18 "twin share" chargers will not have 3,400 kW, unless each now has more than 120 kW. They used to have 120 kW, so it would take 3,400 / 120 = 28, with 56 parking spots/bays, to be equivalent (at peak time) to 1 pack swap machine.

 

[deonb]

OTOH, 18 "twin share" chargers will not have 3,400 kW, unless each now has more than 120 kW. They used to have 120 kW, so it would take 3,400 / 120 = 28, with 56 parking spots/bays, to be equivalent (at peak time) to 1 pack swap machine.

OTOOH, throughput from 28 chargers will be higher than throughput of 1 swapper. If you were to do a 1 hour full charge at a SuperChargers (not directly a common scenario for charging, but effectively what you get with swapping), you can do 40 pack swaps in that time.

In the intended 20 minute charge time, a swapper can do 13 swaps.

So a swapper can't replace that many chargers. I think 10 is pretty much the limit. As it is, nobody will want to pull into position 5 in a swapper queue (unless it's something like a 60 wanting an 85).

 

[Norbert]

In the intended 20 minute charge time, a swapper can do 13 swaps.

I'm not quite following this calculation. In 20 min, with 120 kW, you can charge a maximum of 40 kWh. I'd expect that to be exceptionally low for a charge, unless your *intention* is to make many short stops, instead of a smaller number of longer stops. An average of 70% (to be charged) would still be an equivalent of 20 chargers with 40 bays. I'd expect that those who just want to get a small charge will use the SuperCharger, while those willing to pay for the swap will usually need a large charge. Almost wouldn't make sense otherwise. Meaning, the swap station will reduce the load on the SuperChargers especially by taking those cars needing a larger charge.

So a swapper can't replace that many chargers. I think 10 is pretty much the limit. As it is, nobody will want to pull into position 5 in a swapper queue (unless it's something like a 60 wanting an 85).

Why do you go even further and reduce it to 10? And why would nobody want to pull into position 5? Why would there even be a long queue in front of the swapper, and not in front of the chargers, in the first place?

If you have a large solar canopy, you might very well want battery storage in any case, to maximize the benefit from direct use of solar and reduce grid dependency and/or peak usage. So that aspect, as well, is in synergy with a swap station.

 

[jerry33]

Paying $60 to $80 for a swap eliminates the big advantage of an EV. (e.g. it will cost just as much as a gas car to run)

 

[yobigd20]

IMO I would probably never use it unless it was free. if anything maybe $10 or $20 but only charged for the "swap out" i.e. the swap on the way back to get your own battery back should be free. Anything more and I doubt many people are going to use it unless you're dirt rich.

 

[JRP3]

Paying $60 to $80 for a swap eliminates the big advantage of an EV. (e.g. it will cost just as much as a gas car to run)

Only if you used swapping exclusively. Otherwise the cost to run it will still be much less than a gas car. Plus you'll still never need an oil change, emissions testing and repairs, etc.

 

[deonb]

I'm not quite following this calculation. In 20 min, with 120 kW, you can charge a maximum of 40 kWh. I'd expect that to be exceptionally low for a charge, unless your *intention* is to make many short stops, instead of a smaller number of longer stops.

20 minutes gives you 150 miles, which is enough to get you to the next Tesla Station. More than that doesn't really help - you can't make it to the Tesla Station after that even if you charge for 40 minutes. Similarly with the swapper. For the most part it's not useful that the battery is 80% full. You still can only make it to the next Tesla Station.

And why would nobody want to pull into position 5?

At position 5 you're going to wait for 9 minutes. So now you're paying $80 to save 9.5 minutes instead of paying $80 to save 18.5 minutes (which was dubious to start off with). Yes technically it only starts being actually longer at 13 people in line.

But it's a perception thing. 90 seconds feel like an order of magnitude faster than 20 minutes. You can hold your breath for 90 seconds. However, 10 minutes doesn't feel like an order of magnitude faster than 20 minutes. And 10 minutes is especially a long wait when you have to stay in your car. Compared to a 20 minute wait but being able to get out and do stuff.

If the actual swapper process took 10 minutes instead of 90 seconds, it would be dead on arrival, wouldn't you agree? Literally nobody would pay $80 for that.

Why would there even be a long queue in front of the swapper, and not in front of the chargers, in the first place?

10 people drive up to 10 chargers. No line.
10 people drive up to 1 swapper. A line of 15 minutes.
20 people drive up to 10 chargers. A line of 20 minutes.
20 people drive up to 1 swapper. A line of 30 minutes.
etc.

If you have a large solar canopy, you might very well want battery storage in any case, to maximize the benefit from direct use of solar and reduce grid dependency and/or peak usage. So that aspect, as well, is in synergy with a swap station.

Agree with that. The solar and battery storage math all stay the same. I'm just talking about the actual charger - the thing with the 12 AC to DC converter blocks and the 2 connectors (soon to be 4).

 

[jomo25]

There was confirmation that 60s could be swapped out for 85s. Either you'd need to return it and get your orig pack back or you would get a big bill for the difference.

 

[dennis]

I'm curious how many of those posting on this thread have experience using a Supercharger, rather than just reading what Tesla has said about them. Here are a few facts from my experience with 90kw Supercharging on I5, where the traffic flows at 75-80 mph (reduce times by 33% to reflect 120kw Superchargers):

1. With an average of 20 miles of rated range left (safety margin), it takes 40-45 minutes to get 160 miles of additional rated range, which will get you to the next supercharger 115 miles away travelling at 75mph. Drive time is 1:40, charge time is :45 30 for 120kw supercharger).

2. Currently all Supercharger spaces are siamesed so 120kw is shared between a pair of spaces. The second car to arrive only gets what the first car doesn't need. My experience with this situation at Tejon Ranch was that in the first 10 minutes I only added 15 miles of range because the other MS had just arrived and was pulling a full charge. I moved to a vacant pair and got a full charge immediately. (This was in January when there were few MS's delivered and fewer still travelling I5). With n bays if you are not one of the first n/2 cars to arrive it will take you even longer to charge.

3. Because the Superchargers need to be within walking distance of other amenities (bathrooms, Starbucks, restaurants) there is not unlimited real estate for adding bays. It is hard to envision a 20 or 36 bay Supercharger at either Harris Ranch or Tejon Ranch.

My conclusion is that the Swapper is not just a marketing stunt. It is the solution to a looming real problem as the Model S/X increase in popularity and owners are enticed to take their first road trip because of the availability of Superchargering. If it takes them more than a hour of waiting/charging every 115 miles, they may not want to take a second road trip in their Tesla. So Swappers are not just for impatient rich guys, and Tesla needs to invest in building out both Superchargers and Swappers to enable practical EV road tripping.

 

[Norbert]

20 minutes gives you 150 miles, which is enough to get you to the next Tesla Station. More than that doesn't really help - you can't make it to the Tesla Station after that even if you charge for 40 minutes. Similarly with the swapper. For the most part it's not useful that the battery is 80% full. You still can only make it to the next Tesla Station.

I'm not sure I understand this argument. Your total amount of charging is dictated by the total distance you need to travel. However, you can, and will, make some stops longer and others shorter. In fact, if you eat at one of the stops, you are likely to take more that 20 min, and you'll adjust the preceding and/or following stops and charges accordingly.

Plus: If 20 min (40 kWh) is enough to go to the next station, then 85 kWh will in many cases (where it isn't exactly twice the distance) get you to the second next station. Or, you'll just need a very short SuperCharger stop in between, and if you have done a swap, you still save most of the time. In the not-so-distant future, with 100 kWh batteries, you'll then be able to skip a station even when the distance is exactly twice of that to the next station. And in all those cases, you can arrive with a quite empty battery at the second station, meaning you can take full advantage of swapping at that station (and take a full load off those Superchargers).

And last but not least, your final destination may be in reach, and further away than the next-closest SuperCharger (possibly in a different direction). Even if not, you may want to arrive with as much of a charge as possible.

It just isn't true that charges of more than 40 kWh are not useful. If it were, everyone would have 60 kWh battery only.

At position 5 you're going to wait for 9 minutes. So now you're paying $80 to save 9.5 minutes instead of paying $80 to save 18.5 minutes (which was dubious to start off with). Yes technically it only starts being actually longer at 13 people in line.

I don't know why you think there will be a line in front of the swap station, but even if there was, I'd think in such a case there would also be a line in front of the Superchargers, so you'd save even more time, once the swap line gets a bit shorter. So the two waiting lines will adjust their length relative to each other.

But it's a perception thing. 90 seconds feel like an order of magnitude faster than 20 minutes. You can hold your breath for 90 seconds. However, 10 minutes doesn't feel like an order of magnitude faster than 20 minutes. And 10 minutes is especially a long wait when you have to stay in your car. Compared to a 20 minute wait but being able to get out and do stuff.

90 seconds is in fact more than an order of magnitude faster than 20 minutes. It is alright if any line in front of the swap station causes incoming cars to switch to the Superchargers, since such a line doesn't serve any purpose at all. It doesn't matter whether the waiting lines are in front of the swap stations or in front of the SuperChargers, what matters, at peak time, is the throughput of each.

If the actual swapper process took 10 minutes instead of 90 seconds, it would be dead on arrival, wouldn't you agree? Literally nobody would pay $80 for that.

Sure, so that line will get shorter until it makes sense, again, for those coming in. There is no disadvantage in that. The swap station will still function at its maximum rate, in such a case, which actually is the best-case scenario for its usefulness. Perhaps it will lead to the addition of a second swap station.

10 people drive up to 10 chargers. No line.
10 people drive up to 1 swapper. A line of 15 minutes.
20 people drive up to 10 chargers. A line of 20 minutes.
20 people drive up to 1 swapper. A line of 30 minutes.
etc.

Those 10 people usually don't come in at the same time, that's an artificial scenario and an edge case. However, it doesn't even matter, since at that point, the swap station already serves its full purpose, operating at full capacity, taking as much load off the SuperChargers as it possibly can.

 

[ckessel]

My conclusion is that the Swapper is not just a marketing stunt. It is the solution to a looming real problem as the Model S/X increase in popularity and owners are enticed to take their first road trip because of the availability of Superchargering. If it takes them more than a hour of waiting/charging every 115 miles, they may not want to take a second road trip in their Tesla.

This, again, sounds like a problem with Tesla not building out the superchargers fast enough, both in slots and power capacity, rather than a fundamental technical problem requiring an completely different solution (e.g. swapping).

If the SCs truly suck that bad and it is a fundamental technical problem, then dump those completely and just do swappers.

 

[jcstp]

I don't know if relevant but I understand from reading the forum

-Packswap stations will be installed on places where superchargers are heavyly used
-when having multiple superchargers a battery-buffer is needed because the grid (without expensive work) can not delliver enough juice to supercharge at 120kw at all chargers
-so some suppose the battery-buffer will be the packs stored for swapping
-so the price of a swappingstating is only the swappingrobot, because the battery-buffer is already needed for the superchargingcapability of the heavily used site

So in my oppinion the poppularity of the Model S and supercharging made packswap a possibility on heavily used locations
So if supercharging was no succes, packswap (by tesla) would not have appeared
what do you guys think?

 

[dennis]

This, again, sounds like a problem with Tesla not building out the superchargers fast enough, both in slots and power capacity, rather than a fundamental technical problem requiring an completely different solution (e.g. swapping).

If the SCs truly suck that bad and it is a fundamental technical problem, then dump those completely and just do swappers.

I didn't say that Superchargers "suck so badly" - I was pointing out that as usual the reality is not as good as the marketing hype. You need to use real world numbers to size how many Supercharger bays are needed and what the trade offs are between # of Supercharger bays and putting in a Swapper.

Low duty cycle Supercharging locations will be just fine - you will be in and out in 30 minutes. But for high duty cycle locations like SFO-LA and Boston-DC they won't be able to get enough real estate to satisfy the demand with just Superchargers. Swapping will keep the wait times down and the customers satisfied, in addition to meeting the needs of the truly impatient who are willing to pay to get in and out fast.

 

[richkae]

The most likely road trip I plan to take over the next couple of years will take me past a few superchargers ( and lets assume they all have swappers for this exercise )
The first is at the 100 mile mark. ( +100 )
The second is at the 220 mile mark. ( + 120 )
The third is at the 367 mile mark. (+147 )
The fourth is at the 477 mile mark. ( +110 )

When I get to point A: if I have decided I will definitely be swapping - I drive by. If I might swap or definitely wont swap, I may stop to charge for about 15 minutes depending on how I feel about stopping. If all superchargers are full and I have no direct evidence someone is leaving in the next 5 minutes - I leave.

When I get to point B:
If definitely swapping: I stop and swap.
If maybe swapping: If a supercharger is free I stop to charge. If all superchargers are full, then I can choose to swap or wait. Choosing to swap is based on if there is a queue to charge or if there is a spot that will open very soon.
Driving on is not an option because the point C is out of my range regardless of whether I stopped at A.

When I get to point C:
I need to stop for a short charge ( only 5-10 minutes ) regardless of what I did at B. Its 257 miles including a steep mountain pass from B to D and that is too close for my comfort. If money burns a hole in my pocket, I can swap.
If all superchargers are full, I don't really want to swap again because my battery is half full but I can.

When I get to point D:
This is my last stop. If I charge or swap here - I can easily make it a 700 mile day. If I am pushing for 700 miles a swap would save me time, but I really need some rest so a charge is almost certainly better.
If my family is in the car, I didn't even get this far, we stopped for the day long before this point - they aren't going to tolerate 12 hours in the car.

What's my point?
If I am driving less than 250 miles I don't need any stops.
If I am driving less than 300 miles, I won't bother with a swap at point B unless money absolutely burns a hole in my pocket. I've only got another 80 miles to go from B, and only need 10 minutes of charge to do that comfortably.
If I am driving between 300 and 700 miles, I can do that with combinations of swaps and charge stops. Even if I am keep on swapping, I may also choose to briefly charge at one stop because it is a more efficient use of money. If I don't care about the cost, I can just swap every time.

However having only swap stations would be awful for anyone frugal. All of the times that you stop and only need a partial charge - and there are many - you would not want to swap.

 

[Norbert]

However having only swap stations would be awful for anyone frugal. All of the times that you stop and only need a partial charge - and there are many - you would not want to swap.

I'd agree: either just SuperChargers, or Superchargers plus swap station(s). Exception would be when there is a foreseeable high demand, yet little parking space to begin with, such as perhaps in a city, then there might be a swap station only (or with a very small number of SuperCharger outlets).

I'd think a possible future, in which there are mostly electric cars, would be that many existing parking lots will have fast chargers added, while many gas stations will be turned into a combination of swap station(s) and a few SuperChargers. For now, it seems Tesla's strategy is to not-distinguish the two, and just have "Tesla stations" as single entities, as integral parts of existing parking lots.

 

[Mitthrawnuruodo]

I feel a bit torn between the advantages of battery swapping. Don't get me wrong its a feature that definitely should be included, and I think it's amazing it was there all along, but when I have my Tesla the only time I would use it would be to replace my batter after 10 years of usage. I know that I don't speak for all drivers, but I for one am never in so much of a rush that I can't stop for 30 minutes or less every 3 hours of interstate driving. The way I see it is this is a feature to continue winning over tradition ICE consumers. With such a huge "automotive evolution" they may be able to better analogize swapping with fueling. After paying the $60 a couple times, they may switch over to supercharging completely (which is the future of EV's IMO). This should further address range anxiety and win over more buyers (hopefully). Henry Ford is attributed with saying "If I had asked them what they wanted, they would have asked for faster horses". Hopefully, the end-all of this is people get used to spending a fraction of their long distance commute at a charging station.

Any thoughts?

 

[Bubba]

What's my point?
If I am driving less than 250 miles I don't need any stops.
If I am driving less than 300 miles, I won't bother with a swap at point B unless money absolutely burns a hole in my pocket. I've only got another 80 miles to go from B, and only need 10 minutes of charge to do that comfortably.
If I am driving between 300 and 700 miles, I can do that with combinations of swaps and charge stops. Even if I am keep on swapping, I may also choose to briefly charge at one stop because it is a more efficient use of money. If I don't care about the cost, I can just swap every time.

However having only swap stations would be awful for anyone frugal. All of the times that you stop and only need a partial charge - and there are many - you would not want to swap.

I think about my likely long trips and where the Superchargers are planned from me, assuming there is also a swap location at each Supercharger (doubtful).

When arriving at any of the 3 Superchargers nearest me, I would still have over a 50% charge. They are all going to be between 60-110 miles away from my house.
I cannot imagine that I would select the swap option for $80 if I am arriving at that swap station with over a 50% charge.
I would feel like I am throwing away half of the money.

What is the amount of time to get from 50% to 80% at 120 kw? about 10-15 minutes? That works for me.

I am also assuming that I will start in range mode from my house at the start of the day, then at each Supercharger only recharge to about 80%, without waiting for the slow finish.
So I would likely arrive at my first Supercharger of the day way above 50%. I would arrive at first Supercharger at something like 60% to 70%. So first Supercharger is likely just a really short recharge.

With the spacing of the Supercharger network, I think most people would be in roughly the same situation. If you really have a long trip for the day, your first Supercharger stop would be with a SOC above 50%.
So how many people would really use a swap at the first potential location?

The most likely place where you would arrive with a charge below 50% would be your 2nd Supercharger/Swap location.
Then it becomes a judgment call as to your situation, your need for speed, your time, your pocket, your need to pee, or other factors.

To me, this seems like a swap would only be useful in an emergency situation.

 

[ItsNotAboutTheMoney]

Of course, the fees are speculative. Just as with battery prices, cost minimization is the key. They'd need to make the process simple in order to be mechanically reliable.

I can't believe Elon Musk would even accept it being as costly as the average fill-up.