Weird battery readings on Dr Prius

Discussion in 'Prius v Technical Discussion' started by Camper V, Jun 5, 2026 at 6:53 PM.

  1. Camper V

    Camper V New Member

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    Vehicle:
    2012 Prius v wagon
    Model:
    Two
    Hi Folks,
    Our 2012 V (83k) was doing just fine. Then we parked it for 4 months, and came back to the dreaded p0a80. Seemed suspicious. But we had a graduation party to go to so drove 700 miles; got 40.7 mpg with no issues. Got quotes from Green Bean and a few others but decided to take the battery out and have a look. The sensor wiring was badly corroded, so I replaced it and the bus bars, cleaned everything up, etc. On the bench all the cells were within .03 of each other, so that seems good.

    I put it back in and downloaded Dr Prius. Unfortunately I didn't know about this before removing the battery, so don't have comparison data. Here's what it shows:
    upload_2026-6-5_18-49-5.png

    I am virtually certain that I did not confuse any wires- I bought a good quality harness where the lengths are all correct and it really was not ambiguous as to which go where. And even if I had confused two of them, this oddness is before the crossover point from the sensors being on the positive, vs negative. Also, my wife just drove the car 80 miles and it ran perfectly normally, even though there are warning lights all over the dashboard...

    Well.... Any thoughts? And if we do need a new battery, are some of these companies more reputable than others?

    Thank you!
    Paul
     

    Attached Files:

  2. rjparker

    rjparker Tu Humilde Sirviente

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    Location:
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    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    It appears voltage sensor #8 is not connected or connected to the wrong place. Number 8's 16 volts is divided equally by sensors 7 and 9.

    Has to be a wiring problem of some kind on the sensors since the pack voltage at 231 vdc is reflecting all 14 modules.
     
    Brian1954 likes this.
  3. Camper V

    Camper V New Member

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    2012 Prius v wagon
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    Two
    OK, DISREGARD THIS QUESTION! I decided that 'virtually certain' of the wires was not good enough. Made a map of the old harness and when I opened things back up- sure enough, two wires were reversed. I had them in the correct locations by length, which means that in assembly the positions in the clip were swapped. Thankfully there was enough extra length to position them where they need to be. I suppose the lesson here is to not assume that aftermarket parts will work right out of the box!

    So, this problem may have been caused by corroded wiring, or, it may have been a result of the 12v and/ or the hybrid battery losing charge over 4 months of sitting in the winter. It may be that the mechanic I took it to never thought to clear the code and then take it for a ride. Dr. Prius tells me that I have 65% battery capacity remaining- not great but not an emergency. I have no idea how reliable Dr Prius is but I like his point of view, for the moment!
     
  4. Brian1954

    Brian1954 Senior Member

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    Vehicle:
    2011 Prius
    Model:
    III
    Drive the car for a few days and then post a Dr Prius screenshot again. I am curious if the Delta SOC percentage comes down. The 37% shown in post #1 means that the battery blocks (modules) are not balanced to each other. A healthy battery should have a Delta SOC of 0.0%.