Traction battery indicator breakdown

Discussion in 'Prime Technical Discussion' started by vomwezogi, Oct 3, 2023.

  1. vomwezogi

    vomwezogi Junior Member

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    Update Aug 2025: New graphic

    [​IMG]
     

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    #1 vomwezogi, Oct 3, 2023
    Last edited by a moderator: Aug 30, 2025 at 1:30 PM
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  2. Gokhan

    Gokhan Senior Member

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    Don't believe anything you see in the Internet. This is not correct.

    The exact BEV allocation at the is 6.34 kWh at the 240-V plug. This is stated by the EPA and has been verified by ChargePoint EVSEs.

    The exact BEV allocation at the battery output terminals is harder to figure out, but I get roughly 38 miles at 6.3 mi/kWh on MFD. This is 6.0 kWh at the battery, which is quite higher than the 5.3 kWh estimated by the Internet bloggers. It corresponds to a 95% charging efficiency, which is pretty good, same as Tesla's charging efficiency.
     
  3. Marine Ray

    Marine Ray Senior Member

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    Hmm, what would you change in the graphic?
     
  4. Gokhan

    Gokhan Senior Member

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    5.3 kWh should be 6.0 kWh. The HEV reserve is about right, but perhaps it is slightly higher 1.1 kWh. Therefore, the top buffer is probably overestimated. The bottom buffer could be slightly lower, too.

    I estimated the Level 2 (240-V) charging efficiency to be 95%. Level 1 (120-V) charging efficiency should be around 87–90%, varying with conditions.

    8.8 kWh is 8.79 kWh to be exact.

    Note that the battery capacity also somewhat varies with the discharge rate (C-rate).
     
    #4 Gokhan, Oct 28, 2023
    Last edited: Oct 28, 2023
  5. Marine Ray

    Marine Ray Senior Member

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    You bring up good points, thanks. I base my top and bottom buffers on myriad videos that john1701 has posted.

    I'll stand by my creation, albeit not perfect. You're welcome to create your own :)

     
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  6. Gokhan

    Gokhan Senior Member

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    Oh, I didn't know it was yours. LOL
     
  7. Marine Ray

    Marine Ray Senior Member

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    Yep, I'm a visual learner. Just couldn't grapple how the Prius Prime 8.8 kWh pack allocated top and bottom buffer, EV and HV. My graphic helped me better understand.
     
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  8. Gokhan

    Gokhan Senior Member

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    Battery capacity also drops with mileage. So, if someone sees a drop from 6.0 kWh in a fresh battery to 5.3 kWh in a high-mileage battery, which is 12%, it is not unusual.
     
  9. 100 free watt hours

    100 free watt hours Junior Member

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    I have 213,000 miles on my 2019 Prime. The last few months I've noticed that sometimes the indicator shows the battery has fallen below
    the HV charge line. When this happens the car drives jerky and poor throttle response for a few minutes until it gets charged up to the HV line. I can only charge up to 18 miles now and only get about 14 miles of that. I have charged it everyday, sometimes 2 or 3 times. I use 220v to charge it and it only takes a couple of hours. Incedently, the 110v charging cable that comes with the car can be easily converted to 200v by making a dog bone with 110v going to each leg of the 110v plug. Anyway, it looks like its time to replace the battery.
     
  10. FuelMiser

    FuelMiser Senior Member

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    Yup, looks like you've exhausted the life of the battery. 213K miles is pretty good, I'd say. 2 to 3 charges a day since 2019 is a lot of cycles. Good luck.
     
  11. bisco

    bisco cookie crumbler

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    or could the engine need work?
     
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  12. vomwezogi

    vomwezogi Junior Member

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    digitaliziran.si_static-pages_battery_prius_battery_guide.html (1).png
    After some research and tests - that's probably what we actually have.
    Thanks to Gokhan and Marine Ray.

    Admins, could you please replace the picture in the OP?
     
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  13. vomwezogi

    vomwezogi Junior Member

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    Also I did a test to prove that the 12v battery is charging while the car is plugged in and charging, Level 2 charging was used. IMG_0141.PNG
     
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  14. Tideland Prius

    Tideland Prius Moderator of the North
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    Done.

    Ahh, so fully charged is 93% rather than 85% that we previously thought. Good to know. Thanks for continually researching this and providing us with an updated graphic!
     
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  15. Gokhan

    Gokhan Senior Member

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    Wow, your 12-V battery is failing. It is charging to only about a 40% SOC. In fact, it could be worse because you didn’t measure it after rest. It is curious why it is low. A flooded cell should be at 12.64 V open-circuit after a 12-hour-or-longer rest at 100% SOC. I panic when my AGM cell falls below an 80% SOC (12.65 V). LOL

    Note that when you plug in, the car does not really charge the 12-V battery but keeps it at a float voltage of about 13.0 V to keep it from draining with the electronics being on. This is done through a low-current sub DC–DC converter inside the charger. For the 12-V battery to be charged, you need close to 14.0 V or higher.

    There is more info on the 12-V battery here:

    When there will be 12-V-battery issues, when not, and what to and not to do | PriusChat

    And here:

    AGM battery for Gen 4/Gen 5 Prius/Prius Prime and observations on the 12-V charging system | PriusChat[/QUOTE]
     
    #15 Gokhan, Aug 30, 2025 at 3:11 PM
    Last edited: Aug 30, 2025 at 3:29 PM
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  16. Gokhan

    Gokhan Senior Member

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    I thought that 95% for Level 2 charging was the wall-to-battery efficiency, no?
     
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