Further hybrid system testing and help needed.

Discussion in 'Gen 2 Prius Main Forum' started by Prius92, Jun 28, 2025 at 1:30 PM.

  1. Prius92

    Prius92 Active Member

    Joined:
    Sep 14, 2019
    504
    111
    0
    Location:
    Iowa
    Vehicle:
    2008 Prius
    Model:
    II
    This is what I'm having issues trying to figure out, and would like some people with a bluetooth scanner to download the Dr.Prius app and help me out to compare data. I'm also posting this to the 3rd gen sub as the system is similar and both generations used NiMH batteries.

    The Prius is supposed to get better MPG in the city than the highway, as the engine is used more on the highway, but so far this has been completely backwards for me.

    In fact, in city driving, I'm lucky to get 34mpg. On a flat road, going 50-53, I can get in the mid 50's. That is with the AC on too.

    The battery itself seems fine, tests fine, so I'm thinking something else is going on.

    Today it was 86 degrees outside, and the battery was measuring around 113 degrees. But when I floored it from 40 to 60 and held it for 5 seconds, I noticed two things, one right away, and one shortly after.

    The discharge shot up to 130.85 amps, the pack voltage went down to 192, then the battery temp quickly rose to 117 degrees.

    When slowing down quickly, the amperage went up to about 80 amps, and the pack rose to 258 volts.

    Now in any electrical system, resistance means heat, and I'm wondering if perhaps there is something causing the electric motor to draw more amperage than it needs, or perhaps there is a bad connection in the inverter from the hybrid pack or to the electric motor causing higher than normal amp draw. Which is what I'm thinking is making the pack get hot as the cooling system for the pack seems normal.

    So here is what I need for some comparative data. If you can't give me all data points, that's fine, just pick one.

    1. Your current outside temperature (on car or just from a weather app), and then the temperature of the battery pack, car must not have been driven for at least 4 hours, and this temp reading is with the ignition on (KEO), but not in ready mode (don't press brake to power on).

    2. Either having a buddy look at your phone or recording the screen, floor the car from either a stop or on a straight road and tell me what it shows for the discharge amperage and pack voltage.

    3. Do the same above, but quickly come to a stop from 30-40mph (don't slam on brakes, just quickly slow down) and record the charge amperage and pack voltage.

    4. Drive the car for 30 minutes (or just do this after driving your regular commute) and record the outside air temp and the battery pack temps.
     
    #1 Prius92, Jun 28, 2025 at 1:30 PM
    Last edited: Jun 28, 2025 at 1:36 PM
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    26,315
    17,238
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV