Gerasimental
Member
Didn't Elon also mention that the stationary cells would be lower density, or was that just speculation here on TMC?
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Didn't Elon also mention that the stationary cells would be lower density, or was that just speculation here on TMC?
JRP3
Hyperactive Member
I believe so. I seem to remember something like 200Wh/kg stationary as compared to 250Wh/kg automotive.
jhm
Well-Known Member
If I were in Tesla marketing, I would encourage them to drop the language "stationary storage." It is such a static, inert sounding concept. Rather they should call their devices, "power servers." This is much more dynamic and better conveys what they do. These are intelligent, programmable and networkable devices that manage variable power needs absorbing low cost energy when available and delivering high quality power when needed. So these devices literally serve power, analogous to how computer servers provide data and computing power on demand. A power server is much more than just storage.
Gerasimental
Member
Good point. I have found 'stationary storage' to always sound unwieldy and unexciting when explaining the concept to people. And after all, it really IS much more than just 'storage'. It is also a power hub that optimises the power use of a household, business, or grid while giving additional benefits like back-up power or (maybe) high power charging.
I think it's unlikely though that the company that released a car with an 'Insane Mode' and that names its robots after superheroes will release such an important new product under the name 'stationary storage'. It's just a convenient term that basically describes in the simplest way what the product is before any official announcement is made.
jhm
Well-Known Member
Isn't that 3 or 4 year old technology? I'm hoping they've got a 300 Wh/kg cell by now. They should if they're on track to doubling per decade. So 300 would be the new automotive grade, and 250 would be left for stationary apps.
JRP3
Hyperactive Member
I'm not aware of any evidence that they are using higher energy density cells at this point in time. Doesn't mean improvements aren't ongoing, but they aren't necessarily linear, only that there is an average improvement over time.
Clprenz
Member
I'm going to bet that Tesla is using high density cells for the 70kWh, and will increase pack size for 85kWh -> 100kWh, That would be inline with the increase in density and would meet the timeline for using older cells for power servers (Nice! aka:Stationary Storage). This would (will) be a big pivot for the company for a new line of products while updating the Model S in time for Model X.
JRP3
Hyperactive Member
So you're completely discounting the fact that Tesla has already stated that the 70 is just using more cells than the 60?
When and where did Tesla state this? They didn't state it in the blog for the 70D.
vgrinshpun laid out very compelling evidence that they are using better cells on pages 37-40 of this linked thread.
wcalvin
Member
DC house wiring
AC is great for motors compared to DC. And AC allows for transformers to get the voltage high and thus keep that current low to minimize I^2R heat loss. There are high voltage DC transmission lines (Columbia River to LA; Quebec to Boston, many other shorter runs); doing the voltage step up and down is old tech by now.
But once you have on-site storage with strings of batteries in series, you have your choice of voltages as DC. And path lengths can be short enough that series resistance stays low. So you redo the house wiring to get a DC circuit for the computers, a bigger one for the BEV. For devices with motors, you will probably still want AC. But there are inverters for that.
AC is great for motors compared to DC. And AC allows for transformers to get the voltage high and thus keep that current low to minimize I^2R heat loss. There are high voltage DC transmission lines (Columbia River to LA; Quebec to Boston, many other shorter runs); doing the voltage step up and down is old tech by now.
But once you have on-site storage with strings of batteries in series, you have your choice of voltages as DC. And path lengths can be short enough that series resistance stays low. So you redo the house wiring to get a DC circuit for the computers, a bigger one for the BEV. For devices with motors, you will probably still want AC. But there are inverters for that.
JRP3
Hyperactive Member
One of the EV websites had a statement from Tesla that the cells are the same, can't remember which one, maybe GreenCarReports.
Found it:
2015 Tesla Model S 70D: First Drive Of New Electric Car Base Model (Page 3)
Vgrin failed to take into account the fact that the weight difference between the old 60 and the 85 was not great enough to account for the 25kWh difference, which means Tesla probably used some ballasting to keep the weight difference less than 200lbs, which would have required separate crash testing. We know the 60 packs had "dummy" cells in them. The extra range of the 70D may be a result of Tesla feeling more comfortable with allowing a greater percentage of the pack capacity to be used.
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jhm
Well-Known Member
Well, this is truly disappointing. After 3 years, Tesla has no upgrade on cell density. Techically, vgrinshpun's analysis is correct that density at the pack level has improved, even if only by throwing off ballast. Even so, a lack of progress at the cell level is disappointing this close to the release of the Model X and the Gigafactory.
This still leaves open the possibility that Tesla has an abundance of 250 Wh/kg cells which may or may not be tapped for the new line of stationary products. We shall see.
I did not fail to take this into account. I did the calculation and the numbers work assuming 7104 cells in 85kWh pack, 5012 cells in 60kWh. Taking Panasonic data for cell weight (45.4g), 209 lbs accounts for a difference in cell weight: (7104-5012)*0.0454/.454=209lbs. Additional 14lbs (223-209) are likely to be weight savings on the pack level.
The above data/calc is not consistent with dummy cells theory, and this was the basis of the conclusion in my original post.
I still believe that jury is out on this one. I would like to know who was the Tesla spokesmen David Nolan (author of the article) got the statement from. If that was a person on the Service Center level, I would take any statements with a grain of salt.
JRP3
Hyperactive Member
Just because they aren't using a higher density chemistry now doesn't mean there has been no progress. In fact we know at the retail level higher energy density cells are available from Panasonic.
I admit that my thinking was the original 60-85 weight difference was only around 180lbs, but the data from the manual you used does not support that. It's possible that the new 70 packs found some weight savings not at the cell level, but at the pack level.
Job Description: "Furthermore, the suite of grid-connected battery systems developed by Tesla also performs a variety of high value functions for utilities, businesses, and residential customers"
I think this plays to the instantaneous nature of where batteries will first be used, not so much the storage, or arbitrage of miss-matched production and use. Utilities need to firm up supply, when resource switching and during intermittent times. When California specified 1.3Gw, not 1.3Gwh, I think the burst capacity is what they are trying to mandate. No idea of duration, and I'm not a techie there. As far as the interrelationships, I think a lot of what has yet to unfold with demand-response (V2G @10kw, etc) and the potential advent of demand-charges on home users, are things that this posting could be speaking to. Systems need to intelligently react to multiple real-time variables. I can see complex algorithms employed, where utilities can taper down Tesla charging, discharge their own batteries, judge how suddenly they want to ramp up a fossil unit, and at what market price or avoided cost all these choices are made and things happen.
There is also profit to be made in deploying the meters that make all of this possible.
I think this plays to the instantaneous nature of where batteries will first be used, not so much the storage, or arbitrage of miss-matched production and use. Utilities need to firm up supply, when resource switching and during intermittent times. When California specified 1.3Gw, not 1.3Gwh, I think the burst capacity is what they are trying to mandate. No idea of duration, and I'm not a techie there. As far as the interrelationships, I think a lot of what has yet to unfold with demand-response (V2G @10kw, etc) and the potential advent of demand-charges on home users, are things that this posting could be speaking to. Systems need to intelligently react to multiple real-time variables. I can see complex algorithms employed, where utilities can taper down Tesla charging, discharge their own batteries, judge how suddenly they want to ramp up a fossil unit, and at what market price or avoided cost all these choices are made and things happen.
There is also profit to be made in deploying the meters that make all of this possible.
Just call the battery pack: Model P
P for power. (and a cute nod to Panasonic)
For Business, call it Model P(L) for Large scale.
or P-10 and P-100 for 10kWh and 100kWh variants.
I don't know if the price will get to be "that low" - under $10K would beat all competitors right now. However, consider that charger-inverters for at least 2KW that outputs a good sign wave and charges with intelligence and has a 10-year warranty will not be cheap to produce.
P for power. (and a cute nod to Panasonic)
For Business, call it Model P(L) for Large scale.
or P-10 and P-100 for 10kWh and 100kWh variants.
I don't know if the price will get to be "that low" - under $10K would beat all competitors right now. However, consider that charger-inverters for at least 2KW that outputs a good sign wave and charges with intelligence and has a 10-year warranty will not be cheap to produce.
jhm
Well-Known Member
Oncor microgrid gives a peek into the future of distributed energy | Utility Dive
This is a very good article on microgrids. The Tesla 200 kW battery seems to be central to the whole operation. Autonomous and self-configuring, I'd like to know who's driving that technology. Also gives perspective on the economics of such a system.
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I like the name, but P-100 needs to refer to a 100 kW (power) system, not 100 kWh (storage). The key thing that is being delivered is power, and storage is just a means to that end.
This is a very good article on microgrids. The Tesla 200 kW battery seems to be central to the whole operation. Autonomous and self-configuring, I'd like to know who's driving that technology. Also gives perspective on the economics of such a system.
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I like the name, but P-100 needs to refer to a 100 kW (power) system, not 100 kWh (storage). The key thing that is being delivered is power, and storage is just a means to that end.
jhm
Well-Known Member
I guess throwing 560 kW of diesel at the problem does not seem too bright either.
What's the deal on Oncor not being able to own storage? It seems like a regulatory separation between T&D and power generating utilities. I wonder if this might actually be an opportunity for end users to own storage and provide demand response back to the T&D.
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