• Jul 9th 2010 at 5:29AM
  • 12
During an interview with a group of American media this afternoon in Nagoya, Japan, Toyota president Akio Toyoda revealed that his company is already in the process of building a prototype electric vehicle with a Tesla battery pack. The statement came in response to questions about the relationship between Toyota and Tesla. As time ran out, we did not have an opportunity for further follow-up or clarification.

However, both Toyoda and executive vice president Shinichi Sasaki both indicated that Toyota was interested in comparing Tesla's battery configuration against their own internally developed battery. Toyota has a joint-venture with Panasonic that is building larger format automotive batteries that are similar to those used by most other manufacturers. By comparison, Tesla uses commodity 18650-format cells that are typically found in laptop computers. The Roadster's pack contains 6,831 such cells.

The long-term durability of the Tesla approach is still very much in question as few Roadsters have accumulated high mileage – especially in harsh conditions that more mainstream cars would experience. We may or may not ever see a Toyota car with a Tesla battery pack publicly, as it all depends on the results of this study.

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    • 1 Second Ago
      • 5 Years Ago
      This video 1:38 has Elon saying there will be a Toyota - Tesla prototype shown this year:
      • 5 Years Ago
      The issue of replacing damaged cells, it is addressed somehow?
        • 5 Years Ago
        Google doesn't cough up a specific answer, but surely Tesla can swap out bad parts at some level in the hierarchy. `The ESS contains 6,831 lithium ion cells arranged into 11 "sheets" connected in series; each sheet contains 9 "bricks" connected in series; each "brick" contains 69 cells connected in parallel' "Each of the 11 modules carries a monitoring PCB (with its own microprocessor)" and "each of the thousands of cells has two fuses (one each for the cell’s anode and cathode)". I suspect one of the modules will know something's wrong, you swap that out, then you look for the bad brick in it and/or check 789 individual batteries ;-)

        • 5 Years Ago
        I just have some experience with blown prismatic LIFePO4 cell. The only thing which changes that you have minus 3.2V. But anyhow I will exchange it, for the sake of higher end speed in the 36V setting. But for larger voltages this should be neglectable if the inner resitance of the dead cell is low- in the opposite case they should shortcut the damaged cell completely if exchanging is impossible. May be tht is Teslas IP ;-)
      • 5 Years Ago
      I highly doubt it. Tesla's pack isn't at all advanced - it really is just a pack of 6,000 cylindrical cells. Cylinders don't stack particularly closely, so the pack ends up very large. Yes, you can run lots of cooling through the sticks of cells but large-format prismatic cells shouldn't have overheating issues and even if they do, they don't need as much space for cooling as you get between stacked cylindrical cells. I also wouldn't think Tesla has much IP in the arrangement of cells.

      Toyota moved away from cylindrical cells on the Prius in 2001 with the introduction of the NHW11 model. Most people will never have seen or driven the original NHW10 but there are a few that were grey-imported into the UK, Australia and New Zealand from Japan.The lithium-ion pack used in the plug-in Prius has prismatic cells, I believe.

      Of course it's possible that Toyota are talking about using the removeable pack design from the Model S in two years time, and this speculation could be complete rubbish.
        • 5 Years Ago
        Don't confuse "Tesla battery pack" with "Tesla Roadster battery pack"...they could be two different things. Especially if Toyota is just now in the development stage...
        • 5 Years Ago
        Cylindrical cells may be desirable for Gen1, especially for EV with very large battery pack because it is cheaper to produce with the existing mass production process. Cost (low) and reliability should be highest priority for Gen1 and subsequent generations will deal with fancy space efficiency, etc...
        • 5 Years Ago
        Yep - they could be combining Tesla's world class battery management system with the large format cells that allow higher power/energy density.
      • 5 Years Ago
      no doubt Toyota is playing with EV drive now. as for batteries, it seems to me that the pouch style larger cells will be the way to go in the future. the laptop cells tesla use is not because they are ideal but because they exist..

      the pouch style is a convenient form, easily stackable and apparently lends itself to the nature of the battery too. light weight as well.

      if we take A123 as an example going from their famous 26650 cylindrical cell it improved about 35% in energy density with a larger pouch cell as well as a bit higher power density too.
      must be cheap to make too.

      the future for batteries is so bright it has to wear shades :)

      remember there is only 30$ worth of lithium metal in all the nissan leaf battery pack..
      • 5 Years Ago
      Leaf Question: Is the 12v accessories battery in the car also Li Ion?
      • 5 Years Ago
      • 5 Years Ago
      This is interesting but not surprising. Toyota is not leaving a single stone unturned. They wanted to see if going large format or 18650 is a better approach. I am sure whatever they decide would be the best approach.
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