Model S battery can not be replaced with a different size battery

[Chas F]

I am listed the exact text from an e-mail from Walter Franck below. Again, this was from March 2012:

This confirms what I have always suspected. I have no reservations about banking on an upgrade in 8 years. If not from Tesla then a third party will fill the void.
Not like its a bet with my retirement stash or anything, but I've seen enough. This will happen and I will take that bet any day.

- - - Updated - - -

Honestly, I would never recommend anyone get the 40 kWh pack. IMHO the 60 should be the baseline pack size.

Respectfully, that statement in the absence of any other of 100 variables is somewhat meaningless. This choice depends on expected usage, commuting distance, driving style, and finances among other things.

 

[RDoc]

I'm surprised that there's any difference between a 60 kwh supercharge capable car and an 85 kwh car beyond some minor software parameters. It would be interesting to hear an explanation of why a 60 kwh owner couldn't just buy an 85 kwh battery and have it installed if they wanted more range today, although they might not get any more performance. Of course, Tesla might not have any batteries available if they need all of them for new car production currently. Since the battery is a structural member in the car, it would be surprising if the physical sizes and structural characteristics were different.

The other wildcard in all this is third party battery refurbishers. With the kinds of production volumes Tesla likely will be doing, it sounds like a viable market. Hopefully Tesla hasn't done something like encrypted the battery ID to prevent such rebuilding and upgrading.

 

[Doug_G]

Respectfully, that statement in the absence of any other of 100 variables is somewhat meaningless. This choice depends on expected usage, commuting distance, driving style, and finances among other things.

Meaningless, no. My opinion, yes. True in 100% of all situations, no, but I can make a case for it.

If finances are at issue and you don't need much range, then a Leaf is probably a better choice, or maybe a Volt. If finances are not at issue then I would strongly recommend the 60 kWh pack for everyone.

From my experience with the Roadster, which provides similar range to the 60 kWh Model S, that range is sufficient for the vast majority of usage. It's enough for long distance travel if you're careful and have charging infrastructure of some kind available. For in-town use it's enough range that most people will never encounter "range anxiety".

Given the impact of cold on range I would strongly advise against the 40 kWh pack for areas that experience extreme temperatures. The pack heating upon startup would consume too large a chunk of the available range.

 

[ElSupreme]

I'm surprised that there's any difference between a 60 kwh supercharge capable car and an 85 kwh car beyond some minor software parameters.

Well I believe the battery packs have a different number of cells. So they would weight different amounts. And they would have a different number of sensors. And the cells and sensors might be (I don't think anyone outside of Tesla knows) different configurations of sensors and cells. The center of mass of the pack could be different. The coolant volume could be more or less. The 60kWh pack might need more, or less, aggressive cooling/heating, meaning a smaller or larger heat exchanger. Or perhaps dampers around the same heat exchanger.

The point I keep trying to make is that the battery in a Tesla is COMPLEX. And it provides COMPLEX outputs to the car, and requires COMPLEX inputs from the car. Just swapping out one for the other will not work.

I imagine it is a software/firmware headache to change these cars over. You have to reprogram the battery level, and all the monitoring systems. You have to reprogram the cooling and heating software. You have to remap and reprogram all the battery sensors.

Physically I see a big problem setting up the suspension when going from one to the other. You need to have a very close total mass and center of gravity to be able to swap them.

Overall Tesla has decided at this point they are not going to try to develop methods to change all of these in a car. I bet they feel there is little business for new packs. I doubt very many people will only want a new battery after 8 years. They will want a new car. An for used cars you can just buy a replacement battery of the same size.

The aftermarket has a HUGE advantage here. They don't have to provide a 100% perfectly integrated solution for a bigger pack. Tesla would have to. And as I said before. Tesla CAN do this, they just aren't planning on it at the moment. If there is a strong business case for this I expect Tesla to offer upgrades to packs (with supercharging hardware being a big hic-up here) and even higher capacity packs in the future.

 

[GSP]

I'm surprised that there's any difference between a 60 kwh supercharge capable car and an 85 kwh car beyond some minor software parameters. It would be interesting to hear an explanation of why a 60 kwh owner couldn't just buy an 85 kwh battery and have it installed if they wanted more range today, although they might not get any more performance. Of course, Tesla might not have any batteries available if they need all of them for new car production currently. Since the battery is a structural member in the car, it would be surprising if the physical sizes and structural characteristics were different.

The other wildcard in all this is third party battery refurbishers. With the kinds of production volumes Tesla likely will be doing, it sounds like a viable market. Hopefully Tesla hasn't done something like encrypted the battery ID to prevent such rebuilding and upgrading.

If I remember correctly, Tesla has said that there is a weight difference between the 85 kWh and 60 kWh packs. Also that this mass difference requires different suspension parts.

This may be more of a PIA for Tesla to upgrade batteries, but just like putting a Honda V6 into a 3-cylinder Insight, the aftermarket will do it.

GSP

 

[ElSupreme]

If finances are at issue and you don't need much range, then a Leaf is probably a better choice, or maybe a Volt. If finances are not at issue then I would strongly recommend the 60 kWh pack for everyone.

There is a big gap between the range of a LEAF and a 40kWh Tesla. I would be over the LEAF range 2 or 3 days a week. And more because of the style of my driving. Because I drive long distances the Volt doesn't offer me fuel free driving, and I would be better off buying a high MPG gasoline car.

Given the impact of cold on range I would strongly advise against the 40 kWh pack for areas that experience extreme temperatures. The pack heating upon startup would consume too large a chunk of the available range.

I would agree about worrying about range loss due to environmental factors, and driving style. But there is a window above the LEAF where the 40kWh Tesla fills. I am in a niche driving habit where a LEAF or Focus EV isn't quite what I need. The 40kWh Tesla would be fine for 98% of my driving, where the LEAF would be only about 60%.

I think if you drive a lot every day, but don't go on long trips often. Your weekly schedule has days a LEAF wouldn't cut it. AND you don't want your car for more than 4-5 years then the 40kWh car would be great.

I decided to go from 40 to 85kWh based almost solely on the fact that I want to keep this car for 10+ years. I don't think I would want to keep a 40kWh car for 10 years. And I was doubtful (but very very hopeful) about upgrading packs since day one. Supercharging really sealed the deal for me. At first I thought it was more PR than practical, but I have completely changed my mind there.

 

[VolkerP]

Well I believe the battery packs have a different number of cells. So they would weight different amounts. And they would have a different number of sensors. And the cells and sensors might be (I don't think anyone outside of Tesla knows) different configurations of sensors and cells. The center of mass of the pack could be different. The coolant volume could be more or less. The 60kWh pack might need more, or less, aggressive cooling/heating, meaning a smaller or larger heat exchanger. Or perhaps dampers around the same heat exchanger.

The point I keep trying to make is that the battery in a Tesla is COMPLEX. And it provides COMPLEX outputs to the car, and requires COMPLEX inputs from the car. Just swapping out one for the other will not work.

I imagine it is a software/firmware headache to change these cars over. You have to reprogram the battery level, and all the monitoring systems. You have to reprogram the cooling and heating software. You have to remap and reprogram all the battery sensors.

A sophisticated EV architecture would put all these pack-size dependent control logic inside the pack so it gets swapped along with. The BMS in the replacement pack would report only these parameters to the car that the car can handle. And take care of all the pack size specific stuff by itself.

Physically I see a big problem setting up the suspension when going from one to the other. You need to have a very close total mass and center of gravity to be able to swap them.

Yes. But Tesla never listens to people seeing big problems. :wink:

 

[rcc]

What I've heard is that all the Model S battery packs weigh the same and have the same weight distribution, etc. They put in ballast if they use fewer cells. This way they don't have to recrash test anything and the suspension tuning stays the same.

What I don't know is how self-contained the pack is from a cooling perspective. I expect there to be plumbing connections with the car but are the pumps in the car or in the pack? My guess is in the car but I could be wrong. Same question applies to whatever else they use to cool the coolant.

Regardless, any new pack has to be compatible with the cooling hardware on the S and the physical properties have to almost identical to current packs. Will future cells allow that? No one knows for sure so Tesla can't promise anything.

S/W complexity around energy management is actually the least worrying. That's all software in the pack and the car which can be changed in the future.

 

[David-El]

I saw this on Tesla's site also. I do hope that this changes in the future. I would have bought the 40 kWh and been fine for now, and sometime down the road, 8 years or so, was planning on just getting a larger pack to be able to drive longer distances between charges. My reasoning is probably similar to others, that battery capacity will continue to increase in the coming years. The only reason I upgraded to the 60 kWh is for the supercharging access. If that was available with the 40 kWh I would have stayed with it. Here's to hoping that this will eventually change.

 

[Chas F]

Meaningless, no. My opinion, yes. True in 100% of all situations, no, but I can make a case for it.

If finances are at issue and you don't need much range, then a Leaf is probably a better choice, or maybe a Volt. If finances are not at issue then I would strongly recommend the 60 kWh pack for everyone.

From my experience with the Roadster, which provides similar range to the 60 kWh Model S, that range is sufficient for the vast majority of usage. It's enough for long distance travel if you're careful and have charging infrastructure of some kind available. For in-town use it's enough range that most people will never encounter "range anxiety".

Given the impact of cold on range I would strongly advise against the 40 kWh pack for areas that experience extreme temperatures. The pack heating upon startup would consume too large a chunk of mthe available range.

That's my point Your experience wouldn't apply to everyone so a 60 kWh recommendation may not be the right one. I live in FL, so your case for cold weather wouldn't apply. "Around town" is also a relative metric. Depends on the town, where you live in it, and how much you drive.
I don't mean to sound argumentative or to insult. I've put a lot of thought and calculation into selecting the 40kWH, based on my specific environment and think there must be others in similar situations so a blanket recommendation may not be helpful.

 

[DFibRL8R]

I'm a bit annoyed that this declaration that the battery size can't be changed is just now being posted on the message board ESPECIALLY since the Facts page says it is technically possible to upgrade to a larger battery (though not recomended)! When I configured in September, I chose not to spend the extra $$ figuring I would have the potential to upgrade in the future to a better/faster/cheaper battery as technology improved and costs inevitably come down if I wanted to. I have supercharger access. I believe an explanation from Tesla is in order as to why one area of their website says something is possible and another now says it can't be done? Maybe George Blankenship could weigh in on this.

 

[ElSupreme]

I'm a bit annoyed that this declaration that the battery size can't be changed is just now being posted on the message board ESPECIALLY since the Facts page says it is technically possible to upgrade to a larger battery (though not recomended)!

It IS technically possible. Tesla recommends not to buy a smaller battery because they might not OFFER an upgraded pack. All they have added to the conversation is that they do not plan on offering upgrading of battery packs.

 

[sp4rk]

Tesla also mentioned somewhere, at sometime ... no idea where but I know I read it, that batteries were (to be) compatible with "switching" technologies ala Better Place. We don't see that, either.
One day, maybe ...

 

[jerry33]

Tesla also mentioned somewhere, at sometime ... no idea where but I know I read it, that batteries were (to be) compatible with "switching" technologies ala Better Place. We don't see that, either.
One day, maybe ...

AFAIK, that was in 2009. They haven't said much about it since. If they had a current plan to offer an upgrade, they wouldn't be selling a pre-paid replacement at eight years. Now eight years is a long time and things may change but Tesla has always said to get the size that you will need in the future rather than getting a smaller pack [and hope Tesla will come up with something].

 

[Doug_G]

That's my point Your experience wouldn't apply to everyone so a 60 kWh recommendation may not be the right one. I live in FL, so your case for cold weather wouldn't apply. "Around town" is also a relative metric. Depends on the town, where you live in it, and how much you drive.
I don't mean to sound argumentative or to insult. I've put a lot of thought and calculation into selecting the 40kWH, based on my specific environment and think there must be others in similar situations so a blanket recommendation may not be helpful.

I'm not meaning to dismiss your analysis, but that's a point in itself: you've done a detailed analysis to come up with your answer. An average person who isn't an EV enthusiast or early adopter type isn't going to do that, or even know how to do that. So for the average person "off the street" I would still make the same recommendation.

If you've done the math and got your answer, then by all means go for it. That's the right one for you.

You didn't respond to my point that a Leaf might be a better choice for a person who only needs limited range and has budget limitations.

 

[Chas F]

You didn't respond to my point that a Leaf might be a better choice for a person who only needs limited range and has budget limitations.

I didn't mention the financial aspect because others on this thread addressed that pretty well, but since you ask: I would rather own an ICE than to buy a LEAF. It is not to my taste. The model S is a beautiful car and even the 40kWh range and performance make it a great car for me. The only budget limitation I've considered is that while the 40kWh works for me, the 60kWh would give me more of a warm fuzzy, but it's just not worth an extra $10K. In other words, the "warm fuzzy" and increased performance is lower on my list of financial priorities than vacations, home renovations, etc. Personal choice.

 

[dsm363]

I'd agree with Doug_G's recommendation that people go with the 60 kWh pack if they are new to EVs unless they've done what Chas F has done and that is a thorough evaluation of their current and future use and are ok with the range. As long as people understand the limited range and are ok with it, they the car is identical to the 60 kWh basically and still a great car. I would rather have someone have a car with range they only occasionally need than get something that doesn't suit their needs because they didn't think things through well and then tell their friends that the Model S doesn't work well because the range is nothing.

 

[Chas F]

I can agree with Doug_G and dsm363 in the context of the last couple of posts. I considered myself an "average person off the street" and assumed everyone would do some sort of math to determine the right car for them. Maybe this is not a good assumption. Thanks for talking thru it.

 

[jandkw]

Just quickly review this forum and have two comments:

1. Some of you in this forum says that “Tesla is pushing for the bigger battery pack” for profits, which is true. Another main reason is that this is part of Tesla’s Supercharger network strategy. The six California Supercharging stations is not a good example because this is Elon’s home town and he can build as many and in close range proximity as he wants. If you look at the East Coast corridor, the distance between Milford, CT (Milford Travel Plaza) and Newark, DE (Delaware Welcome Center) is exactly 178 miles. This is Tesla’s Supercharger plan all along and that is to plot all their supercharging stations for their network within the range of say, less than 200 miles so obviously the 40KW Model S will not be able to make it. The announcement of Model X proves the point that they didn’t even bother to offer the 40KW because the mini-van customers/families will drive their X for family vacations often so they can use the superchargers.
2. “Why someone would want to buy the same 85KW battery with the range of 300 miles while the improved 85KW has the range of 800 miles”. I consider battery is the crown jewel of EV technology. Remember the advent of microprocessors in the PC industry? They introduced the first IBM PC using the 8086 micro and then followed by the 80186, 80286 and so on. These are highly sophisticated development and chip processing but they upgraded every 18 months based on the market demand. A lot of people said PC was a toy and could not be the mainstream computing. It only took a few short years to silence the critics. Now we have the revolutionary EV and the battery is the key technology of all which makes me believe that the technology will improve overtime with enough demand like the microprocessor technology. Understanding that the demand does not necessarily come from US which they are dragging their feet due to the heavy concentration of ICE manufacturers and the knowhow. I see even higher demand in the world market, places like China, India and Europe while the pollution is an issue today for some countries and continue to be one. IMHO, the 85KW of 300 miles range will improve, and with so many battery researches going on one promising technology can provide the 3-5X capacity in eight years. So now the next thing for Tesla to do is to endorse the new technology and form factor and make it as a replacement battery product for the Model S. After all, this new form factor will be used on their next generation of cars along with their competition.

In my humble opinion, whether the Model S battery can be replaced with a different size of battery or not, that is not the issue. If the demand is there, Tesla is a hardcore engineering company, they will figure out a way to do it and that includes develop the improved battery packaging even with a different form factor battery to satisfy the customers’ demand. Market will drive the initiative.

 

[Kleist]

Ok, ok, I hear you... here is the deal for upgrading from a 40kWh or 60kWh battery pack to an 85kWh battery pack on the Model S

- $40k for the new 85kWh battery pack ( that is what I am charging on a new vehicle )
- $10k for disassembly and dispostioning of the old battery
- $5k battery exchange fee at the service center
- $2k shipping and handling
- plus applicable taxes

if you are want to sign up please raise your hand.