Range and Battery Linearity?

Aptera Community Aptera Discussions Range and Battery Linearity?

Aptera Community Aptera Discussions Range and Battery Linearity?

  • Range and Battery Linearity?

     John Malcom updated 1 week, 4 days ago 10 Members · 10 Posts
  • SonicMustang

    Member
    October 12, 2021 at 11:19 pm

    Can someone from Aptera explain how the relationship of range to battery size is possible? 250 miles on a 25kWh pack, 400 miles on a 40kWh pack, 600 miles on a 60kWh pack and 1,000 miles on a 100kWh pack doesn’t seem to account for the extra weight of the larger batteries. Exactly how can the 1,000 mile range Aptera have the same efficiency as a 250 mile range Aptera when it’s lugging a battery that’s four times bigger and four times heavier?

    Speaking of batteries, how heavy are all four packs? I read somewhere a Tesla 85kWh pack weighs 1,200 pounds.

  • Joel Smith

    Member
    October 13, 2021 at 6:00 am

    Not “from Aptera” but…

    It is pretty clear those are goals, estimates and conveniently round numbers based on their early simulations. I recall Chris saying as much in one interview or other, along with the suggestion that the numbers could easily be even better. Actual pack sizes (kWhs and weight) and standardized range assessments won’t be available for a while yet, so you will have to be patient for those along with the rest of us.

    And, of course, your results may vary.

  • Joshua Rosen

    Member
    October 13, 2021 at 6:18 am

    If the shorter range batteries were LFPs and the long range battery is NMC then the weights could be the same. LFP batteries only have half the energy density as NMCs but they are much cheaper and have longer cycle lives.

    BTW I’m assuming that the battery sizes quoted are usable storage, not true size, because they are quoting ranges that are 10X the pack size. The real sizes would have to be at least 10% bigger.

  • Davis Edwards

    Member
    October 13, 2021 at 6:22 am

    Not from Aptera, but…

    I believe Chris said they are using 2170 cells (see image). Some quick searching says those weigh 68grams and hold ~15Wh. That would equal 25kWh of cells weighing ~250lbs, 40kWh of cells weighing ~400lbs… 100kWh of cells weighing ~1000lbs. Nice how that math works out. Of course, there will be more weight associated with the pack, but to get us in the ballpark

    • Ray Holan

      Member
      October 14, 2021 at 4:15 pm

      Davis, thanks for doing the calculations of estimated pack weights. I’ve been wondering about that. As of now, I spec’d my Aptera with the AWD and the 250 mile (i.e. 25kWh pack). My experience with hypermiling my old Honda Insight taught me that adding even 100 lbs. made a noticeable difference in MPG (i.e. range). Thus, I’m assuming that the smallest pack with the highest power powertrain would be best acceleration based on lowest weight of the vehicle.

  • kerbe2705

    Member
    October 13, 2021 at 8:28 am

    I think Joel Smith hit the nail on the head.

    • John Malcom

      Member
      October 14, 2021 at 10:01 pm

      Absolutely agree!

      Of course only estimates based on simulation/calculations since no production ready vehicles of each configuration were available for real world testing. As the prototypes mature and are tested we should get performance reporting from real world testing and eventually from government testing.

  • John Locke

    Member
    October 13, 2021 at 2:03 pm

    The difference in weight between the 25 and 40 KWH pack is about the same as adding a passenger. Not likely to make a big difference in efficiency. The 100KWH pack on the other hand is bound to make some difference depending on how much rolling resistance changes. The dominant factor though is still likely to be wind resistance which won’t change with increased weight.

    • Curtis Cibinel

      Member
      October 13, 2021 at 5:14 pm

      They are definitely rounding some things for simplicity. 30lb = 1% efficiency was quoted and tracks with the physics. Here is a fun calculator on weight and THEORETICAL range – make a copy to edit it. The 600 mile version was quoted at 1800 lb so that was my starting point.

      Disclaimer: Not all values are from quoted statements and the sheet uses estimates to fill in the missing data. This is not official and is pure physics not real world.

      https://docs.google.com/spreadsheets/d/1Tuu7avKH2dS_JPk7aiP2av09a1f1WE0OvvNH6fdHpiQ/edit#gid=0

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