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Can anyone help me make sense of this battery data / comment on any concerns?

Discussion in 'Gen 2 Prius Main Forum' started by pmelc1, Nov 12, 2023.

  1. pmelc1

    pmelc1 Junior Member

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    Screenshot_20231112-145453_Dr_Prius[1].jpg Screenshot_20231112-143902_Dr_Prius[1].jpg Screenshot_20231112-144057_Dr_Prius[1].jpg Screenshot_20231112-143848_Dr_Prius[1].jpg Screenshot_20231112-132959_Dr_Prius[1].jpg Screenshot_20231112-132427_Dr_Prius[1].jpg [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
    Are the temporarily high resistances of bank 1 and 2 a concern? How about the consistently [slightly] lower resistance of bank 10? The voltage difference and state of charge seems normal from what I've read. These screenshots are the odder ones mixed with a couple normal, the majority showed nothing apparently abnormal.

    The car's power feels normal to me, though mileage is a good bit worse than it used to be. I should mention the 12V battery dies easily and needs a little juice from jump box. 12V battery is about 2-3 years old. For many years, it dies easily in the winter and needs a jump some days esp if cold and sitting for more than a day.

    The mechanic was concerned that the combimeter may have failed due to changes in voltage from hybrid battery, and that the battery should be checked out first to make sure a faulty hybrid battery doesn't damage a newly installed replacement of combimeter. I explained that with this model and year, combimeter failures are common regardless of hybrid battery status / normally not caused by hybrid battery state, but that I would download the app to check the status of the battery/modules before we do anything.

    (I fibbed earlier and said I already had a battery work done just because I didn't want to make that focus of discussion. Getting that done potentially this week. Mechanic wants to change out any problem cells and replace all nuts and bus bars.)
     
    #1 pmelc1, Nov 12, 2023
    Last edited: Nov 12, 2023
  2. Tombukt2

    Tombukt2 Senior Member

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    Combi meter is part of 12V system . HV battery cannot damage 12V system . Even when becomes unisolated.
     
    #2 Tombukt2, Nov 12, 2023
  3. pmelc1

    pmelc1 Junior Member

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    Thanks was not aware of that. The hybrid battery helps charge the 12V battery though right, or am I wrong? Do you see anything of concern with the Dr. Prius data?
     
    #2 pmelc1, Nov 12, 2023
    Last edited: Nov 12, 2023
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    The High Voltage battery powers the DC-DC converter (part of the inverter assembly). When the car is in "ready" mode, that supplies about 14V to run all the low voltage systems and charge the 12V battery.

    You want to monitor voltage difference while driving, sometimes under heavy discharge (accel) and heavy charge (decel). Values at 50 or 100 amps give a better indicator of pack health than 10or 20 amps

    As long as the difference isn't above (approx.) 0.3V for more than a few seconds, the ecu is happy - ie, the pack is staying "balanced".

    Really, the pack capacity has to degrade a lot before is significantly affects MPGs. I do not use block resistance values for much of anything.


    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Nov 12, 2023
  5. rjparker

    rjparker Tu Humilde Sirviente

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    12v battery is 2-3 years old but “for many years” needs a jump? I would check for parasitic draw.
     
    #4 rjparker, Nov 12, 2023
  6. pmelc1

    pmelc1 Junior Member

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    Yes, normally only in winter but sometimes in warmer months also. It seems like close to enough but needs a zap from jump box to start. My trunk does not close properly due to a car accident in 2018, but there are no lights lit. It does date to around that time though. Could this be causing a draw even though there is no obvious power consumption i.e. bulb is not on? I also installed trailer hitch lighting a while back. Again, no obvious usage though.
     
    #5 pmelc1, Nov 12, 2023
    Last edited: Nov 12, 2023
  7. pasadena_commut

    pasadena_commut Senior Member

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    We just replaced our pack and resistance is 19.0 for every measurement with .07 V delta between the highest and lowest voltages. The pack which was just replaced had some resistances in the high 20's and the delta voltages were also a little higher. So the values you see are not out of range for a working pack (brand new to ~17 years old) except for those few resistance measurements.

    The aberrant ones were 134, 215, and 8 milli-Ohms. Did you see these consistently or just once in a while for one frame? I can imagine that if the car gets busy on its communications bus it might result in the odd glitch in the Dr. Prius display. Bad modules really could have resistances that high, but if they were real, they wouldn't come and go quickly, they would stay high. Plus the only way to lower a module's resistance below that of a brand new module would be to short it somehow. I'm about 99.99% sure that Dr. Prius (or the car itself) calculates the resistance by dividing the observed voltage by the observed current, and if either measure is faulty, so will be the resistance value shown. Or one of the values could just be misread entirely.

    Honestly, the first thing I would check is the OBD2 connection of the dongle to the car's port. If that was not plugged in tightly it could introduce a lot of delay and possibly result in some spurious (reported) measurements.
     
    #6 pasadena_commut, Nov 12, 2023
  8. TMR-JWAP

    TMR-JWAP Senior Member

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    A crappy 12v battery/12v system will reduce your mpg significantly. You need to get that sorted out before dumping money into an HV battery that isn't coding or showing any significant problems.
     
    #7 TMR-JWAP, Nov 12, 2023
    Brian1954 likes this.
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