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Maxwell batteries in Roadster?

Discussion in 'Roadster 2020' started by tonybelding, Feb 5, 2019.

  1. tonybelding

    tonybelding Active Member

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    This is just baseless speculation on my part, but… I'm wondering if these Maxwell dry electrode batteries might already be in the Semi and new Roadster prototypes. It would explain some things.

    Even though this acquisition might seem to us like it came out of the blue, I think it's been in the works for A While. Given his past statements and track record on this subject, I don't think Mr. Musk would buy into a new battery technology unless his people have already flogged it hard in testing and are also very familiar with the manufacturing process. We've been told there's a "top secret" area in the Gigafactory that's off limits to all visitors, and it wouldn't surprise me if they already have a pilot production line there turning out Maxwell batteries — not on a commercial scale, but enough to put into vehicle engineering prototypes.

    We've had people for a year scratching their heads over how the Semi and the R2 Roadster can achieve their range specs with existing batteries. So, maybe they don't. Maybe the prototype vehicles have these prototype batteries.
     
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  2. Black Hawk

    Black Hawk Member

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    When Marty and Doc were trying to get the train up to speed in back to the future 3 they used 3 different “fuel souces/logs” to accelerate...

    Yea...how’s that for an oversimplified analogy?

    But I can’t help but wonder about the “ultracapacitor kick” and it’s useability for acceleration, ultra fast charging...a complete game changer... hmmm??

    When doing extreme endurance events(marathon distance plus) animals/humans use 3+ different stored fuel sources.

    Can the different specialities of batteries and ultracapacitors be used in the cars?.....Acceleration, endurance, weight characteristics, energy/power densities?

    Fun times ahead....
     
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  3. MaxPowers

    MaxPowers Member

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    I love the amount of money is going to R and D into battery technology. It will definitely accelerate EV adaption.
     
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  4. CarlK

    CarlK Active Member

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    That makes sense. It's a lot money that Tesla has paid for the company. I'm pretty sure there is a good use of its products in the immediate future if not already did. The same as previous acquisitions of the Michigan stamping company and German automation company. Tesla would have just do R&D itself if it's only some exploratory development.
     
  5. CarlK

    CarlK Active Member

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    One thing I can think of is when ultracapacitors taking over needs of burst acceration and deceleration requirement for battery in those areas can be greatly relaxed. You maybe able to pack batteries closer and reducing the cooling capacity thus saving weight and space. You may even be able to adjust the battery chemistry to optimize for energy density instead of dischage speed. These are just speculations those people are much smater than us. I'm sure this is another innovative move that will keep Tesla's lead in EV technology for many more years.
     
  6. Sean Wagner

    Sean Wagner Member

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    This is where I pipe up and point out that Tesla's very "own" Jeff Dahn said a while [two or three years?] ago that CATL had 300 PhD's working on battery chemistry alone.

    Anything that accelerates the spread of applied knowledge in this area is good news for we the peolep [sic].
     
  7. MaxPowers

    MaxPowers Member

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    Don't get there several 1B+ investments into battery manufacturing in USA and Europe. :)
     
  8. strangethingintheland

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    #8 strangethingintheland, Feb 12, 2019
    Last edited: Feb 12, 2019
    This video clip might shed some light here.

    It contains within it a video clip from an investor conference where the a maxwell officer (CFO?) is speaking from about 3:50-9 minute mark. In particular he indicates that they have had a trial underway with a major OEM EV company. Also indicates they have validated higher energy density (300Wh/kg), and other details (cobalt free) that align with claims tesla has been making. It's not a real stretch to think that they could have been trialing the DBE technology on the Semi and Roadster.
     
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  9. CarlK

    CarlK Active Member

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    #9 CarlK, Feb 13, 2019
    Last edited: Feb 13, 2019
    Here is another piece of information. It's a Seeking Alpha article but it does seem to have some pretty good history on this. It looks Tesla has started working with Maxwell since 2016. It must have a pretty good idea what this can do.

    Maxwell Technologies And The Battery Race With Toyota - Maxwell Technologies, Inc. (NASDAQ:MXWL) | Seeking Alpha

    One thing still not clear is Elon mentioned ultracapacitor while the indication now is that the main interest is dry battery electrode manufacturing. Just wonder what Tesla will do with ultracapacitor.
     
  10. mongo

    mongo Well-Known Member

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    I'm going to be a wet blanket...

    Volumetricly, Roaster and Semi can be done with 2170s. In the Roadster case, a double stack that Elon mentioned in one of the quarterly calls.


    That kick is very short lived, and also requires a second 1,500 Amp power converter to charge/ discharge the caps and translate their fluctuating voltage into something usable for the drive unit.

    The amount of kWh a capacitor bank can hold/ deliver is insignificant compared to the waste energy./ thermal mass of the pack. Energy density is a limiting facto for charge rate, and the caps wouldn't help there.
     
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  11. CarlK

    CarlK Active Member

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    Lithium battery can store a lot of energy but it strains to output large amount of energy quickly. The requirement of high burst power output affects cost and other part of the battery design too. So instead of having to design one that could handle hundreds of kilowatts of power output you can make one with half of that peak output and supplement it with a small ultracapacitor when there is a need. Not sure if this is Tesla has in mind now though since it appears the main interest is the dry battery electrode.
     
  12. mongo

    mongo Well-Known Member

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    The 100kWh pack on an S can output 1,500 Amps at 350V or 525kW and give you 300 miles of range. Half the peak output would mean half the capacity and half the range, not an overal benefit (150 mile range).
    Roadster needs more than a short power burst to hit 250 MPH, something over 450kW to sustain 250 MPH (guess of cd and frontal cross section) along with 3+ kWh of kinetic energy. A Maxwell capacitor bank of 3 kWh would require 706 of their largest durablue parts and take a volume of 0.4 m^3 and weigh 770 pounds. But it would also drain to 0 volts, you would need a much larger bank to have a usable powe source.
     
  13. Krash

    Krash Data Technician

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    #13 Krash, Feb 14, 2019
    Last edited: Feb 14, 2019
    But current batteries already do more than 450kW. So certainly a double stack of two improved chemistry batteries will have plenty of power to sustain 250mph. The problem with the S sustaining 155mph is the cooling. Considering the Model 3 emphasis on cooling for track mode, Tesla likely has a handle on that.

    I think the bigger question is the power required to sustain initial torque and what the advantages are for reducing the battery power down to the minimum needed to maintain 250mph plus some minimal buffer and using ultracapacitors for that power shortfall at initial acceleration. If someone will explain the latter here, I will take a shot at the former based on two P induction motors in back and the 3 LR motor in front. I just assume that is the most efficient motor combo so that the car has top power in the rear at weight shifted launch and the most efficient range at top speed while those rear motors freewheel.

    I realize that the frame and tire setup may not take two of the current induction P motor width, but it is a start. I think mongo"s calculation of volume here will be most interesting. Unlike a battery, my understanding is that ultracapacitors don't need to be all co-located for cooling, they just need big wiring to the inverter, so you can likely safely stash them in creative places in the car layout.
     
  14. mongo

    mongo Well-Known Member

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    #14 mongo, Feb 14, 2019
    Last edited: Feb 14, 2019
    The power on the inital take off ramps from zero due to the car not moving. Work or energy (joules or kWh)= force × distance, at the start some force (only fighting inertia) and near zero distance. Power is the change in energy divided by time (so accelerating faster requires more power (kW) for the same net change in energy (.5*mass*velocity ^2)).

    The power needed hits its maximum at the 250 MPH top speed (or slightly before due to additional power for acceleration). Force is max due to aero, and distance is max due to speed. So the kWh and kW are both high.

    So caps don't help on the low end (minimum power/ energy needed), and would be drained by sustained time at the high end (maximum power needed).

    Unless the idea is just a burst to 250 and back, in which case that needs the 3 kWh mentioned for the kinetic energy plus extra for aero. I didn't check if the energy power available is sufficient with the number of caps I used.

    Edit: power, not energy
     
  15. Krash

    Krash Data Technician

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    #15 Krash, Feb 14, 2019
    Last edited: Feb 14, 2019
    Yes, the idea would be just to boost to 250mph. Only start to use the caps when the torque/traction limit reaches 450kW and then use all caps for the power needed above 450kW until 250mph is reached.

    Is that 3kWh? And if so what are the advantages of reducing the battery power to 450kW? If there were no advantages to having lower max power in the batteries you would never use caps at all since their energy density is lower than the batteries, you would simply make the batteries produce more power.

    Also, my intuition is that the motors will have a power limit that will be reached well before 250mph.
     
  16. mongo

    mongo Well-Known Member

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    3kWh is an oversimplification based on the final kinetic energy of the car at 250 MPH. I'd need to spreadsheet the total energy needed due to aero and rolling resistence during acceleration. That would also give an estimate of peak power.
     

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