Tesla Battery Investor Day

[Buckminster]

In preparation for this day expected sometime in Q3 2019.

Potential agenda:

1. Scene setting (FSD investor day did the techy bit first - it was a mistake)
2. Current capability with updates
   1. 18650 - S/X Refresh quashed or announced
   2. 2170
      1. GF3 suppliers
      2. MY same as M3
      3. Production rates - GF1 update
      4. Battery pack cooling, pack design / manufacturing improvements
      5. Roadster / pickup pack - double height design
      6. Semi pack
   3. Supercharging rates
      1. V3 ramp-up status
   4. Efficiency - M3 0-80% charge in 30 mins gets you x miles
   5. Powerwall - next version, order book status
   6. Powerpack - next version, new orders
   7. Megapack design, California Moss update, new orders
   8. Tesla to start mining - need & update on likely purchase
3. Maxwell purchase - next generation capability
   1. Not using ultracapacitors yet
   2. Cobalt free from 2020?
   3. Manufacturing footprint improvements x16
   4. Backwards compatible
   5. Tesla manufacturing their own battery cells announcement?
   6. 1 million mile longevity
   7. Recycling improved, update
4. Maxwell and Jeff Dahn technological in the weeds improvements
   1. Microscope pictures - look, no dendrites!
   2. Chemistry
   3. Anode deep dive
   4. Cathode deep dive
   5. Cell construction
   6. Dry electrode - solvent free, environmental improvements
   7. Safety improvements
   8. Performance, volume, mass, recharging, 300-500Wh/kg & ~$100/Wh cost improvements (cell & pack levels)
   9. Comparison to competition
5. Long term technology roadmap exists - details another time
6. Wrap up (reminder that Tesla is 5 years ahead) - 1 last thing:
   1. Roadster or semi production launch update?
   2. Solar Roof?? - another investor day
   3. Leaf blower tease??
   4. Maxwell enables aircraft design to start???

Too much? What have I missed?

 

[Buckminster]

Forgot about the drivetrain!

This is the battery and drivetrain investor day....

1. Moving to permanent magnet motors across all cars. Efficiency improvements.
2. Silicon Carbide Mosfets
3. 3 motors in S, X, Roadster - performance benefits
4. Reuse of M3 motors - Semi etc.

 

[ggr]

Tesla is already using Maxwell Supercaps in the new active suspension. But it makes no sense to use them in the battery/drivetrain system.

 

[JRP3]

Moving to permanent magnet motors across all cars. Efficiency improvements.

Can't freewheel the PM motors so efficiency loss when only one motor is needed.

 

[MP3Mike]

Tesla is already using Maxwell Supercaps in the new active suspension.

Do we really know that for a fact?

 

[1101011]

Tesla is already using Maxwell Supercaps in the new active suspension. But it makes no sense to use them in the battery/drivetrain system.

...As we understand it.

 

[JRP3]

Maxwell would need to be sitting on a never before heard of miracle breakthrough for caps to make any sense in a passenger vehicle battery pack. There might be a use in heavy limited range vehicles with a lot of stop and go, like a garbage truck.

 

[Artful Dodger]

Can't freewheel the PM motors so efficiency loss when only one motor is needed.

The Model 3 rear motor design It is not a simple PM motor. It is a switched reluctence permanent magnet assisted (SRPM) motor), designed so its magnetic field can be completely shut off via an electric pulse.

This feature allows a SRPM to rotate without cogging torque when it is turned off (freewheeling is something different). There will still be mechanical drag from bearings, air resistance, etc.

That's also why the new Roadster can achieve a top speed over 250 mph, because their is no back-EMF at high rpm which limits motor speed on a conventional AC motor like in the Model S/X.

The Raven driveline uses the more efficient front motor (the SRPM) to cruise on the highway, while the rear AC motor is put into "torque sleep" mode by its controller.

So your inference of needing to "freewheel the PM motors" is exactly the opposite of what Tesla actually does to increase highway efficiency with the Raven.

 

[JRP3]

Doesn't the 3D use an induction motor for one one the motors? Yes the Ravens get more efficiency from using the pm motor, but the induction motor can freewheel without providing it power when it's not needed.

 

[mongo]

The Model 3 rear motor design It is not a simple PM motor. It is a switched reluctence permanent magnet assisted (SRPM) motor), designed so its magnetic field can be completely shut off via an electric pulse.

This feature allows a SRPM to rotate without cogging torque when it is turned off (freewheeling is something different). There will still be mechanical drag from bearings, air resistance, etc.

That's also why the new Roadster can achieve a top speed over 250 mph, because their is no back-EMF at high rpm which limits motor speed on a conventional AC motor like in the Model S/X.

The Raven driveline uses the more efficient front motor (the SRPM) to cruise on the highway, while the rear AC motor is put into "torque sleep" mode by its controller.

So your inference of needing to "freewheel the PM motors" is exactly the opposite of what Tesla actually does to increase highway efficiency with the Raven.

The magnets in the rotor of the PMSR cannot be turned off. As a result, their motion will cause eddy currents and thus drag. Even if they could demagnetize them with a strong enough pulse, there would be no way to remagetize the different alignments of the composite magnet assembly.

On cars with both AC induction and PMSR motors, when running at light load, it is more efficient to turn off the inverter for the AC motor than the PMSR. If all the motors are PMSR, then they need to either drive them, with resulting switching losses, or turn them off with resulting eddy losses.

While some articles on SR motors claim they do not produce back-EMF, that is based only on the undriven state due to lack of rotor magnets. During operation, they do produce back-EMF as called out in these reseach papers:
http://users.encs.concordia.ca/~pillay/c43.pdf

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.662.959&rep=rep1&type=pdf

http://trace.tennessee.edu/cgi/viewcontent.cgi?article=3286&context=utk_gradthes

http://kaliasgoldmedal.yolasite.com/resources/SEM/SRM.pdf

Here is an appnote from TI showing that in the simple case of a solenoid activating, the motion of the iron core into coil generates back-EMF just like the rotor moving into alignment with the stator does.
http://www.ti.com/lit/wp/ssiy001/ssiy001.pdf
Also consider, if there were no back-EMF (V=0), how is the power generated?


Speed wise: Roadster could run on AC motors with half the gear reduction and double the current/ torque. Motor windings can be adjusted to reduce the V/RPM figure, however there are practical limits to motor speed due to mechanical as well as electrical commutation operating envelopes.

 

[Artful Dodger]

The magnets in the rotor of the PMSR cannot be turned off. As a result, their motion will cause eddy currents and thus drag. Even if they could demagnetize them with a strong enough pulse, there would be no way to remagetize the different alignments of the composite magnet assembly.

It's a "switched reluctance, partial permanent magnet" motor:

Elon Musk on Twitter

"AC induction front & switched reluctance, partial permanent magnet rear. Silicon Carbide inverters in both. Performance drive units are lot sorted for highest sigma output & get double the burn-in."​

We have this discussion every time the topic of SRPM motors comes up. What's it been, 10 months now? Here's our last go-round from Jan 4, 2019.

In his teardown video, Sandy Munro says he doesn't understand how the Model 3 motor works. That's because he hasn't studied SRPM principles of operation. He doesn't do any basic tests either. He says "Halbach Array" but never checks to see if one side is highly magnetic and the other isn't (works like a fridge magnet; it's not hard to check).

Are their coils of wire wrapped around those magnets? He never shows the assembly, only the glued together magnets. Are the magnets made of different materials like oh say, Neodymium and Alnico? If he asked these questions, we'd already how the motor works.

So here's the premise: the Tesla SRPM motor uses a composite magnet (a lamination of two magnetic materials w. end caps). Magnetic flux can follow either an interior path inside the magnet (the "off" mode), or an exterior path outside the magnet ("on" mode).

That's how Tesla could create a switchable permanent magnet. Once its switched on with a brief pulse of DC electricity, it stays remains a permanent magnet without any further energy input (unlike an electromagnet). It can switched off by a pulse of DC current of the opposite polarity.

BTW, this design explains how the Tesla Semi can produce 100% torque at stall without overheating: it's not doing any work when it's not moving, just like your knee isn't doing any work when you're standing upright, but it still opposes the force of gravity. Oh, and like the Semi, your knee doesn't heat up either when you're standing still.

So I've linked this video before, but do watch the part where the presenter demonstrates how he toggles a switchable composite permanent magnet. A pulse of DC current in one direction turns it on, then a 2nd pulse with reverse polarity turns it off. What it really does is expel the magnetic flux to turn the magnet on, then brings the flux path back inside the composite magnet to turn it off. The money shot comes at 8:00 in the video:
("Give it a little pulse")

So that's switched reluctance, and its Telsa's secret sauce. That's why the Model 3 rear motor is 90% efficient, and the Model S/X's AC motors using electromagnets are 80% efficient. The hard part is writing the code for the high-speed controller, which has to pulse the magnet on and off rapidly to achieve the desired torque output.

But at least there are no RPM limits due to the number of poles like an AC motor. That's why the new Roadster can do 250+ mph top speed yet still be able to perform 0-70 mph wind sprints for an hour without overheating. A P100DL would start rolling back power after the 3rd hard launch. Roadster did 60 such launches back-2-back on reveal night in Nov 2017.

SRPM is the secret sauce, and it's going to be in all Tesla vehicles going forward.

 

[JRP3]

Then why did they bother to put an induction motor in the front of the 3D if the SRPM motor takes no power to idle? And why leave the induction motor in the Ravens?

 

[mongo]

We have this discussion every time the topic of SRPM motors comes up. What's it been, 10 months now? Here's our last go-round from Jan 4, 2019.

Yeah, and you were incorrect back then. The magets are in the rotor, not the stator. My guess is that they guide the flux of the inner pole pair to allow for smaller physical communtation angles.

Are their coils of wire wrapped around those magnets? He never shows the assembly, only the glued together magnets.

The teardowns showed that the magnets are inserted into slots in the rotor.
Another Tesla Model 3 Teardown Highlights Strengths & Opportunities For Tesla | CleanTechnica

So here's the premise: the Tesla SRPM motor uses a composite magnet (a lamination of two magnetic materials w. end caps). Magnetic flux can follow either an interior path inside the magnet (the "off" mode), or an exterior path outside the magnet ("on" mode).

The magnets are five sections adhered together, no end caps.

That's how Tesla could create a switchable permanent magnet. Once its switched on with a brief pulse of DC electricity, it stays remains a permanent magnet without any further energy input (unlike an electromagnet). It can switched off by a pulse of DC current of the opposite polarity.

Yes, you can do that to a magnetizable material, but why? The field needed to do that (and resulting drive electronics requirements) would be much greater than the normal max torque value and turning them off doesn't seem to produce any useful results for a motor.

BTW, this design explains how the Tesla Semi can produce 100% torque at stall without overheating: it's not doing any work when it's not moving, just like your knee isn't doing any work when you're standing upright, but it still opposes the force of gravity. Oh, and like the Semi, your knee doesn't heat up either when you're standing still.

The semi can produce 100% torque at stall because all that is needed is to maintain the current in the stator. With no back-EMF due to rotation the only losses are the (likely oil cooled) stator winding resistance and switching losses. With an AC motor, the rotor needs to be energized with the full torque field which is why it overheats.

So that's switched reluctance

Switched refers to electrical commutation, not enabling/disabling magnets. Standard SR motors have no magnets.

Switched reluctance motor - Wikipedia

This greatly simplifies mechanical design as power does not have to be delivered to a moving part, but it complicates the electrical design as some sort of switching system needs to be used to deliver power to the different windings.

 

[Buckminster]

>400 Wh/kg in ~2024

 

[mongo]

>400 Wh/kg in ~2024

And that is high cycle batteries (airplane applications with mutiple charge discharge cycles a day). I believe Tesla Energy cells are less energy dense than Tesla Automotive.

 

[Brando]

BMW’s future EVs could outlast the competition by 200 miles

https://electrek.co/2018/06/25/bmw-next-gen-electric-powertrain-technology-ix3/
side note: calling a larger battery pack "new technology" is silly, right?

So does this mean that BMW looked at Model S/X and discovered how AC induction motor does NOT use magnets and BMW decided that was a good idea. So does this mark BMW as ~ 15 years behind Tesla? Does BMW think they can improve on the AC induction motor efficiency?

BUT time/science moves on and we have PMSR motor which is more efficient. Now Model S/X still have no real competition (and yet Tesla continuously improves). So keep making large AC induction motor for rear drive of Model S/X and add smaller Model 3 motor to the front.
Part of the "Raven" improvement is the Model 3 PMSR as front motor for S/X.

Might the SEMI end up with 2 different motors? OR yet a 3rd design? We really don't know. Tesla DOES work on continuous improvements so we shouldn't be surprised IF Tesla finds motor combinations or adding supercapacitors or new motor designs or battery designs or inverter designs as improvements.

As I have mentioned before, I also think Tesla - IF demand drops off - could offer TAXI/Limo/rental companies special built single motor versions of the model S/X. (of course autonomous, FSD, could well eliminate this idea/need). I'm surprised that the electric London Taxi isn't selling more - are they at their build limit? Not enough batteries like everyone else??

enough of my rambling thoughts for today
Seems only China may offer real competition in the near term. We shall see.

 

[JRP3]

The batteries themselves will have a potential range of 420 miles (about 200 miles more than what others currently offer)

First, Tesla is already at 370 miles, so that would only be 50 miles more than currently available, and second, this is probably NEDC bullsugar rating, not EPA, so no improvement at all.

 

[Buckminster]

Another likely discussion point:
Tesla patent paves way for compact battery systems that are easier to produce

I believe the phase change material is intended as a heat buffer, and it would not circulate. The coolant would be additional channels either inside the cell volume or inside the phase-change filled battery module. The advantage is that the cooling system wouldn't have to be able to immediately react to high thermal load, but would have time to ramp up - while all cells are still kept near the optimal 30°C temperature due to the phase-change thermal buffer material.

I believe the gist of the new cell module system outlined in this patent application is (as you said):

• Cells put in an upright position, connected to a single base plates on both the anode and collector sides.
• Cells immersed in coolant, instead the current copper channels that are snaking between the cells:
• 
  
  
• In the above picture, the adhesive between the cells is replaced by free space and filled with coolant.
• Note that the current 100 kW pack design is basically a plastic enclosure for the cells:
• 
  
  
• This does not offer much structural integrity AFAICS, the cells do not appear to be mechanically connected to any load bearing elements - I believe. (Note: speculation only, this could be wrong.)
  
• With the new design, if I'm reading the patent correctly, the cell anode/cathode surfaces are soldered to the base plates. This could have serious load bearing properties (at the risk of exposing the soldered connections to fatigue).
  
• Another important element of the patent is that the 'plates' might be sandwich structure printed circuit boards. The advantage is that the connection and grouping (topology) of the cell groups can be changed later on by changing the interconnection layout of the printed circuit - without having to perform any mechanical change on the assembly side. PCBs are also excellent structural elements.
• The PCBs might also have active circuit elements embedded already: sensors and other fine-grained battery management system components.
• The rest of the patent is about how to structure the plates so that different modules can be combined. This again adds assembly flexibility, as these modules can be combined via overhanging conducting elements that offer both structural and electrical connections.

It's a pretty clever design all around, and shows what pack design they are be working on for the next generation of vehicles.

That battery module patent is really clever, I take my hat off to the patent lawyers who wrote that, it describes everything, while being opaque about what the real innovations are.

What I think it is describing is a new way to manufacture cells, a module at a time.

1. The cell casing for a group of modules is created as a single unit. [ cheaper, faster, no waste material ]
2. Those cells are filled with electrolyte in parallel. [ faster ]
3. Instead of an end cap, the collector plate(s) are used to seal the cell. [ cheaper ]
4. The collector plate(s) are used connect to the anode and cathode, and contain the circuitry to connect them in parallel. [ cheaper, more robust ]
5. Modules (collector plates) have overlaps, which allows them to be connected together in series. [ cheaper ]
6. Protection systems which where on a per cell basis are now on a per module basis. [ fewer redundant systems, cheaper ]
7. Optimisation of battery, module and cell at the same time. [ cheaper, faster, better energy density ]
8. Better more consistent cooling. [ longer lasting, higher power ]

This was filed in March so given time for drafting, this is the state of Tesla's thinking about 9 months ago. I'm not sure how solid state electrolyte fits in with this.

 

[Artful Dodger]

This comment is nominally about the Cybertruck reveal planned for Nov 21, but I hope you'll agree it belongs here in Battery and Powertrain Investor day. Let's summarize what we know/think about Cybertruck and its place in Tesla's vehicle lineup:

• Price: < $50K base price
• Major competitor: Ford F-150 class
  
• Competetion annual sales volume: > 2M+ units
  • Ford F-150: 850K
  • GMC Sierra: 750K
  • Ram Trucks: 600K
  • Import Brands: 250K

Telsa has bitten off a large chuck to chew. But Tesla is sufficiently mature as a Company now so we can say they wouldn't enter this market without a solid plan to compete and win. Let's see if we can reverse engineer some key aspects of that plan.

So let's assume 500K Cybertrucks per year (to start), with 200 kwh batteries per truck. That's 100 GWh of bty cells per year (to start), or about TRIPLE the current output of GF1/Sparks.

So I suspect that the 'one more thing' at the Thu, Nov 21 Cybertruck reveal could be an announcement about its bty technology and in-house production plans. I don't think 500K/yr volumes will be taken seriously by Investors without introducing the bty plan. That would also set the stage nicely for 'Bty and Powertrain Investment Day'. On Nov 21, do the following:

• announce bty specs and volume plans
  
• lay out the questions on how to achieve these goals
  
• tell us when to expect the answers (Bty Investor Day)

Further, I expect to hear about a new modular bty architecture that will be shared between Cybertruck, Plaid S/X/R2 and Semi. This will smooth out bty production planning when all future new products draw from the same pool of battery cells and modules.

Bonus prediction:
Megapack uses these modules too. 1 Million mile bty that can also power your house. Modules can be added or removed from vehicle or home.​

If Cybertruck demand is slow to take off, battery cells and modules can be diverted to accelerate other products. If demand is high, that's where Investors step up with cash to accelerate plant construction.

That's also why its obvious that Tesla will open reservations for Cybertruck on Nov 21. The company needs evidence of solid demand for its product in order to get a good response during any capital raise.

Your thoughts?

Cheers!

 

[Buckminster]

This comment is nominally about the Cybertruck reveal planned for Nov 21, but I hope you'll agree it belongs here in Battery and Powertrain Investor day. Let's summarize what we know/think about Cybertruck and its place in Tesla's vehicle lineup:

• Price: < $50K base price
• Major competitor: Ford F-150 class
  
• Competetion annual sales volume: > 2M+ units
  • Ford F-150: 850K
  • GMC Sierra: 750K
  • Ram Trucks: 600K
  • Import Brands: 250K

Telsa has bitten off a large chuck to chew. But Tesla is sufficiently mature as a Company now so we can say they wouldn't enter this market without a solid plan to compete and win. Let's see if we can reverse engineer some key aspects of that plan.

So let's assume 500K Cybertrucks per year (to start), with 200 kwh batteries per truck. That's 100 GWh of bty cells per year (to start), or about TRIPLE the current output of GF1/Sparks.

So I suspect that the 'one more thing' at the Thu, Nov 21 Cybertruck reveal could be an announcement about its bty technology and in-house production plans. I don't think 500K/yr volumes will be taken seriously by Investors without introducing the bty plan. That would also set the stage nicely for 'Bty and Powertrain Investment Day'. On Nov 21, do the following:

• announce bty specs and volume plans
  
• lay out the questions on how to achieve these goals
  
• tell us when to expect the answers (Bty Investor Day)

Further, I expect to hear about a new modular bty architecture that will be shared between Cybertruck, Plaid S/X/R2 and Semi. This will smooth out bty production planning when all future new products draw from the same pool of battery cells and modules.

Bonus prediction:
Megapack uses these modules too. 1 Million mile bty that can also power your house. Modules can be added or removed from vehicle or home.​

If Cybertruck demand is slow to take off, battery cells and modules can be diverted to accelerate other products. If demand is high, that's where Investors step up with cash to accelerate plant construction.

That's also why its obvious that Tesla will open reservations for Cybertruck on Nov 21. The company needs evidence of solid demand for its product in order to get a good response during any capital raise.

Your thoughts?

Cheers!

Not convinced the Cybertruck will be the catalyst for the new cells / modules. Also, $50k Cybertruck won't have 200 kWh.