Prime's Traction Battery

Discussion in 'Prime Technical Discussion' started by LithiumMan, Oct 5, 2016.

  1. LithiumMan

    LithiumMan Junior Member

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    Some battery questions:

    Does the 8.8 kWh battery in the Prime provide both the hybrid and the pure-EV function?
    If I recall, the 201.6V hybrid batteries in Prius Gen III and IV have about 1.3 kWh capacity, feeding a DC-DC doubling converter to get about 400V for the motor.

    The specs on the Prime battery are 95 series cells at 25 Ahr, providing 351.5V (which would be the expected 3.7V for a fully-charged LiFe single cell). So, I gather the Prime doesn't need a DC-DC converter to power the electric motor?

    If there is only a single high-voltage battery of 95 series-connected cells, how is its capacity divided between hybrid operation and pure-EV operation? Is it possible that the capacity division setting is flexible and can change depending on driver habits?
     
  2. bisco

    bisco cookie crumbler

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    yes. it's not really divided so to speak. it's available for ev down to a certain state of charge, similar to lift back, then hv only. but you can put it in hv mode any time, and it will behave like the lift back, and preserve the battery charge at that point.
     
  3. LithiumMan

    LithiumMan Junior Member

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    Bisco--"yes" to which of the three questions? Thx.
     
  4. bisco

    bisco cookie crumbler

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    sorry, see my edit.:) i don't know the answer to the converter question. i guess anything is possible, but i haven't read about a flexible ev/hv cutoff point.
     
  5. LithiumMan

    LithiumMan Junior Member

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    Cool
     
  6. LithiumMan

    LithiumMan Junior Member

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    With the Gen III Prius going 75 mph up a long hill (3+ mi) on the interstate, the hybrid battery display will show it virtually depleted. At this point I can detect loss of acceleration available for the hybrid system because the electric motor, I presume, is no longer contributing.

    With the Prime, I wonder if it will dip into the reserve EV battery capacity to keep the electric motor going.
     
  7. Lee Jay

    Lee Jay Senior Member

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    These are not LiFe, they are Lithium Ion. LiFe is 3.2V per cell, not 3.7V and these are 3.7V (fully charged, they'd be over 4V - as much as 4.3V if you don't care about life time, more like 4.1V if you do).
     
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  8. LithiumMan

    LithiumMan Junior Member

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    Hmm, I thought LiFe is required in vehicles, since Li Ion (Lithium Manganese) is less safe with respect to over-charge heating and also to impact heating (witness Samsung smart phones). Also, LiFe generally has a longer life of several thousand charge/discharge cycles vs Li-Ion's 500 or so cycles.

    UNLESS--unless Toyota is using the new solid electrolyte Lithium Ion cells, which are very safe to impact and last many thousands of cycles.
    Is that what they're using? (I read that Dyson is designing an EV car using these cells).
     
  9. bisco

    bisco cookie crumbler

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    keep in mind, toyota has already been putting li-on into the pip for 4 years, and also the euro v.

    but to answer your question, no, it will not dip into the reserve. however, there is a charge a mode that will allow you to charge the battery with the engine while approaching a mountain, so you will have plenty of power to get up the hill with.
     
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  10. LithiumMan

    LithiumMan Junior Member

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    Whoops, forgot to say, the Dyson EV is powered from the thrust of 19 rear-facing Dyson Cyclone vacuums :LOL:
     
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  11. Trollbait

    Trollbait It's a D&D thing

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    There is no specification on what type of lithium chemistry a traction battery has to use. Tesla uses a modified version of the cells used in a laptop. Any serious fire threat from impact should be exposed in standard crash testing, and car packs aren't charged up as fully as in other devices to extend life.
     
  12. GT4Prius

    GT4Prius Active Member

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    Can't remember the exact details, but as you will know the Prime memorises routes and associated power demands, so does it possibly do this automatically after a few trips?

    Posted via the PriusChat mobile app.
     
  13. drash

    drash Senior Member

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    Prime will have a DC-DC converter but it's only for traction battery to accessory battery (12V). It uses an inverter to drive the AC motors. All motors in every Prius use Permanent Magnet A/C motors except for the Prius E-Four which uses an induction AC motor in the rear.

    Nobody uses Lithium Iron Phosphate (LiFePO4) batteries in the auto industry.

    ECU controlled division of the battery.


    Unsupervised!
     
    #13 drash, Oct 6, 2016
    Last edited: Oct 6, 2016
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