Battery Swapping/Rental for the Model S

NigelM · Jun 24, 2012

Mods: I couldn't come up with a better sub-forum for this, please move if you think it belongs elsewhere.

Theory is clear - Model S battery packs can be exchanged, and under the right circumstances it could be done relatively quickly.

However, I've consided the current reality with some friends and the practical difficulties make it seem unlikely to happen in the near future:

* Battery exchange on the Model S is only quick if there is the proper jig available. I believe there are 26 bolts (exact number?) to be removed and re-inserted, as well as the coolant hoses which need to be clamped, disconnected, reconnected and then do an air bleed.

* The above would require not only a car lift but also the correct hydraulic platform for lowering the battery and replacing it with the new one. Could be quite an investment in hardware, the costs for which need to be amortized, for something that doesn't happen frequently. Arguably Tesla service centers will have this anyway but there's not many of those as yet.

* Who carries the capital investment involved in the spare battery packs? It's probably fair to say this is the single most expensive component of the car - $20k cost? 30k, 40k? - What about insurance? Who is responsible?

* Combine the first 3 points above and we are probably looking at costs much higher than a rental car and maybe an hour to swap out the battery at each end of the trip. Questionable if anyone would really want to pay?

* I'm buying my Model S and I intend to look after it and charge appropriately, limited range mode charging etc. Now, I'm going on a long trip and want to swap batteries along the way. Well it's probably faster to just use a supercharger. But if I do swap batteries how do I know that the one I'm getting has been treated as carefully as the one I'm giving up - how old would it be? Etc.

* If I'm leasing the car, do I have a different point of view? Maybe, but I might still be concerned that I'm giving up a new battery for one that has degraded substantially?

* Supercharges make the whole idea of battery swaps redundant don't they?

Theory was fine, but I don't think battery swapping/rental is going to happen.

Discuss?

ElSupreme · Jun 24, 2012

I think battery swapping only makes sense in a few circumstances.

The first is fleet vehicles, where the fleet owner buys extra battery packs and a changing jig. Think Taxis. But then supercharging may be more appropriate. Unless you would see accelerated wear on batteries super charging them all the time.

The second is for small battery owners wanting to road trip. You could got to a Tesla service center, have them swap the pack you rent (sure costs would be similar to renting a whole car) and drive 300 miles. Questions come up here about supercharger equipment and not being able to supercharge your rented 300 mile pack. But this also allows Tesla to build 700 mile packs (whenever that becomes feasible) and rent them to people. This might help offset some battery pack development costs in the future.

But in reality I think Tesla is being smart. They have designed the car to quickly swap packs, even though the need isn't really there. But if the need arises they wont have to get a bad solution, or no solution at all.

dsm363 · Jun 24, 2012

I agree with ElSupreme. I can see people one day going to local Tesla service center to rent a big pack. Tesla would store your specific pack to return to you when you were done with rental pack. For most travel though the Superchargers would take over.

jerry33 · Jun 24, 2012

A simple changing jig doesn't have to be particularly expensive. A few pieces of tubing welded together, accurately, and a jack to raise and lower the battery. You would also need a car lift. Of course, you could spend more and make it fancy with power jacks and 46 motorized socket drivers, which would cost a lot more.

I agree with ElSupreme that there are only a few instances where swapping would make sense, and I'll add one: Jurisdictions where installing superchargers would be very costly or prohibited by some odd regulation.

BYT_P1837 · Jun 24, 2012

I can see battery swapping getting more popular down the road as the chemistry get's better, they get denser and our current packs start degrading!

Edit Note: Can I also say that I love posting here because I can edit!

doug · Jun 24, 2012

ElSupreme said:
The second is for small battery owners wanting to road trip. You could got to a Tesla service center, have them swap the pack you rent (sure costs would be similar to renting a whole car) and drive 300 miles.

Tesla talked about this feature back in 2009, but they have stepped back from it, or at least have been quiet about it lately. Perhaps for marketing reasons.

SCW-Greg · Jun 24, 2012

I don't think it needs to be as complicated as you make it out to be Nigel. I could see the coolant system as completely self-contained with many of the management systems on pack... where only a data connection in addition to power are the only connections needed.

How the coolant releases it's heat I'm not exactly sure, but if you look at today's refrigerators, they don't outwardly show any radiator like the old ones. They're very modular/self contained in design. Perhaps Tesla is doing something similar? If they have that solved, then a 5 minute change becomes possible.

And I agree with Jerry, the battery lift doesn't necessarily need to be expensive, or overly complex.

The pack costs are definitely an issue, but if you're swapping, that means a driver is coming in with one of his/her own, so inventory maybe more of a managed inventory "fleet" thing. I wouldn't doubt that Elon and team have the funding allocated for this in their plan.

My 2cents.

doug · Jun 24, 2012

SCW-Greg said:
I don't think it needs to be as complicated as you make it out to be Nigel. I could see the coolant system as completely self-contained with many of the management systems on pack... where only a data connection in addition to power are the only connections needed.

How the coolant releases it's heat I'm not exactly sure, but if you look at today's refrigerators, they don't outwardly show any radiator like the old ones. They're very modular/self contained in design. Perhaps Tesla is doing something similar? If they have that solved, then a 5 minute change becomes possible.

umm.. you don't need to speculate about stuff that is known.
There are coolant lines, data lines, and power lines all with quick connect fittings at the top of the battery pack. There are three heat exchangers at the front of the car.

SCW-Greg · Jun 24, 2012

Also...

I read a year or two back about some testing going on in Japan with drive through stations - think Jiffy Lube - where they were testing some cars with swappable battery packs to alleviate the charge time issue. I don't know how the results of that went, but I like the "drive through" concept.

Further, if *many* people swap their packs on a regular basis (means there are a lot of cars on the road with a lot of people opting for this charge option), then the issue of "bad" packs in the field would likely go down, as bad drivers (pack abusers) have less time to influence a single pack. So packs in general will find their own life/range average. So this might be something that rolls out in two or more likely three years, vs next year. Also works well with Tesla profitably models too.

Back to that Jiffy Lube idea... Do you think Tesla might create/allow battery pack service/swap center franchises?

SCW-Greg · Jun 24, 2012

doug said:
umm.. you don't need to speculate about stuff that is known.
There are coolant lines, data lines, and power lines all with quick connect fittings at the top of the battery pack. There are three heat exchangers at the front of the car.

On the S... Did not know. Thank you Doug.

jerry33 · Jun 24, 2012

Although this video is old, it clearly shows the heat exchangers.

SCW-Greg · Jun 24, 2012

jerry33 said:
Although this video is old, it clearly shows the heat exchangers.

Great vid. Interesting, so while you might be able to swap a battery in under a minute (with pit crew efficiency), Nigel's original assessment of bleeding lines etc, might not be that far off base then.

It's all stuff to be ironed out in the coming years for sure.

jerry33 · Jun 24, 2012

SCW-Greg said:
Great vid. Interesting, so while you might be able to swap a battery in under a minute (with pit crew efficiency), Nigel's original assessment of bleeding lines etc, might not be that far off base then.

My understanding is that there are quick connects (probably similar to those in a pneumatic hose) so bleeding the coolant lines shouldn't be required.

TEG · Jun 24, 2012

I got this from talking to Tesla:

Model S remains designed to accept pack swaps if they ever need it to. (Useful for service at a minimum.)
Original target was trying to get 1 minute swap capabilty, but it is more like "under 5 minutes" now.
They currently don't have a business case to offer customer pack swap stations, but could change if it starts to make sense someday.

jerry33 · Jun 24, 2012

TEG said:
Original target was trying to get 1 minute swap capabilty, but it is more like "under 5 minutes" now.

Compared to every other car-with-a-battery that I've heard about, under five minutes is wonderful. It means, at a minimum, that the cost of replacing the battery will really be just the battery cost.

dsm363 · Jun 24, 2012

Replacing the battery in the Roadster requires hours of labor I believe so at a minimum, the design is smart for that reason as TEG said. It truly is a wonderful and well thought out design.

Mark Petersen · Jun 25, 2012

well the swap time from 1m to 5m is probably because Project Better Place have changed there statement

and battery swap only really make sense if you lease the battery
witch is where Better Place come in, as there hole business model is bild up around battery leasing
and they have said that they have designed there systen to support different battery types, så maybe they are working together

CapitalistOppressor · Jun 25, 2012

TEG said:
I got this from talking to Tesla:

Model S remains designed to accept pack swaps if they ever need it to. (Useful for service at a minimum.)

Original target was trying to get 1 minute swap capabilty, but it is more like "under 5 minutes" now.

They currently don't have a business case to offer customer pack swap stations, but could change if it starts to make sense someday.

I wrote an extensive takedown comment on an article that slammed Tesla's service strategy (ie mobile technicians vs service centers) as hazy, overly expensive and not well thought out (those were the reporter comments in the story). I think I did an effective smack down on all of those points (and other negative comments in the article), but the basic logic I used to refute him is the same here. There is no economic case for major centralized support infrastructure of any kind (such as service centers, or battery swap stations) for an an automotive fleet that does not yet exist.

In any given geographical unit there needs to be a sufficient density of existing cars to support any proposed infrastructure, or the costs involved in setting up and operating that infrastructure will be a financial drain on the company. Tesla is predicting 25k cars on the road, worldwide, by the end of next year. If all of those cars were located in Los Angeles it might make sense to have a service center with some kind of rump battery rental system. Unfortunately, they are going to be scattered all over the world, in unpredictable locations and density.

Considering the lead time to identify, obtain and prepare locations for anything like battery swap, along with the need to have proper customer density to make it economical, I can easily see a potential battery swap network slipping into the next decade. And based on likely improvements in range and charge time, in conjuction with the expansion of the inexpensive turbocharging locations, I would guess that the need for battery swap will be eliminated long before we ever see a network built.

GSP · Jun 25, 2012

doug said:
umm.. you don't need to speculate about stuff that is known.
There are coolant lines, data lines, and power lines all with quick connect fittings at the top of the battery pack. There are three heat exchangers at the front of the car.

Are the type or suppiler of quick connect fittings known? I would be concerned about insuring a good low resistance connection on the high current connections for repeated connect/disconnect cycles.

I also would fret over crossthreaded bolts, coolant leaks, air in coolant, and price for this service. The cost to providers will be high do to capital for spare battery packs, and limited customer base will limit revenue.

I think supercharging is the way to go, and there is no real need for full charges in < 1 hr. There may be a perceived "need" however, but as more people realize what is possible with 300 mi range and 300 mph charging, the public will forget about "needing" 3000 mph charging like ICE cars (and the Volt) offer.

GSP

wycolo · Jun 25, 2012

SCW-Greg said:
It's all stuff to be ironed out in the coming years for sure.

More likely the inverse, with old geezer holding onto original batt in 2022: "my Ideal Range is down to 45 miles, but the foodstore is only 20 miles away, you do the arithmatic, sonny!"
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Battery Swapping/Rental for the Model S

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