Main battery icon always empty

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by prius4ed, Dec 2, 2019 at 4:41 PM.

  1. prius4ed

    prius4ed Member

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    Car was losing power and the main battery fan was always running. Many dash lights were on. I measured two weak cells in my main battery so I replaced them with used ones. I carefully soaked all the copper jumper plates in swimming pool muriatic acid and sanded them with fine sandpaper. I installed the main battery. Right away I noticed the battery icon is empty. Car drives normally but that icon never shows any bars. Did I forget to connect a wire?
     
  2. SFO

    SFO Senior Member

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    Which DTCs (fault codes) are being reported?
     
  3. prius4ed

    prius4ed Member

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    Note the car icon at the top left is full (is it ever not full?) but the battery icon is always EMPTY.

    The battery icon used to work fine before I replaced two of the main battery cells. Did I forget to attach some wires? FA326250-38C3-49D6-88F3-C6CE197978F9.jpeg
     
  4. davecook89t

    davecook89t Active Member

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    If you had forgotten to connect any wires to the HV battery, I would think that you would have a red triangle on your dash, if the car could start at all. If you have no red triangle and your car appears to be running normally, I would suspect the MFD may be failing. I see that it is not reporting an outside temperature either. Has that always been so? Do the other screens (HVAC, Audio, etc.) come up on the MFD and function normally? You may have a loose or corroded connection on the MFD, or some other component on it may be failing.
     
  5. prius4ed

    prius4ed Member

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    The car now has power and never runs in slow motion like before I replaced those two weak cells. I believe the main battery fan stays off although today it threw the red triangle light and a P0A80 code. Boo hoo.
     
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  6. bisco

    bisco cookie crumbler

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    bummer. youll probably have to go the normal route with all the pain in the neck balancing and stuff
     
  7. prius4ed

    prius4ed Member

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    T
    Thanks Dave for the thoughts and help. I’m pretty sure the battery indicator and outside temp always worked fine - until I did the cell replacement.

    however, my climate screen stopped working 5 years ago and a friend helped me Wet that solder joint which made it work again for 2 years before quitting again. I can still turn on the AC using the steering wheel and set the fan speed by adjusting the set temperature using the steering wheel up and down buttons. It’s really crude.

    And last year my entire dash began going dark once a week or so. Even the gas gauge goes dark which makes fuel anxiety a stressful issue.

    but just before I did the Cell replacement I am pretty sure the fuel level and outside temperature always read correctly
     
  8. bisco

    bisco cookie crumbler

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    sometimes reconnecting power to a p/c board can do bad things
     
  9. prius4ed

    prius4ed Member

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    I did learn a lesson: prior to any HV battery repairs, one should record videos or take photos or notes of what is working or not on the MFD and dash...which I didn’t do
     
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  10. prius4ed

    prius4ed Member

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    Can someone
    Can someone kindly tell me how
    To balance the cells? The guy o bought the used cells from told me to run the AC with the “start” light on (which would be run mode) for about 30 minutes until it depletes the HV battery. Then drive it up a hill if possible to completely deplete what’s left of the HV battery.
    Then drive normally to recharge the HV battery.

    I’m asking myself why not just remove the fuel pump fuse and drive the car until the HV battery is depleted? It should take just a few miles. In fact my fuel is low and I could just let it run out of gas (bring a gas can with me to rescue myself) and drive it on battery to deplete the HV battery. That would skip using the AC to deplete it
     
  11. bisco

    bisco cookie crumbler

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    it's complicated. you can find detailed instructions here by searching. there are lots of great threads.

    the cheapo way is a hobby charger and a massive amount of time charging and discharging individual modules.
    the expensive way is a grid charger (hybridautomotive.com) that charges and discharges the whole battery and takes much less time.
     
  12. prius4ed

    prius4ed Member

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    FD507012-1778-42AB-9AD2-8D4E1A1A008C.jpeg
    To SFO:
    Awhile back I had P0420 and CEL constantly. Last month I got the red triangle and car ran weak intermittently and strong other times and the HV battery fan ran constantly - so I replaced the two weak cells.

    Yesterday I replaced the cat and downstream oxygen sensor and cleared the P0420 and P0430 codes.

    Today I drove it an hour and no codes nor red triangle...until I drove to lunch and got the red triangle, CEL and the round brake circle with shoes icon. See picture. Had scanner with me and got P0301. I’m ready to check the sparkplugs and replace the #1 coil pack for $10 if you guys think I should. Car has 148k miles on original plugs and coil packs.

     
  13. prius4ed

    prius4ed Member

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    View attachment 182822
    To SFO:
    Awhile back I had P0420 and CEL constantly. Last month I got the red triangle and car ran weak intermittently and strong other times and the HV battery fan ran constantly - so I replaced the two weak cells.

    Yesterday I replaced the cat and downstream oxygen sensor and cleared the P0420 and P0430 codes.

    Today I drove it an hour and no codes nor red triangle...until I drove to lunch and got the red triangle, CEL and the round brake circle with shoes icon. See picture. Had scanner with me and got P0301. I’m ready to check the sparkplugs and replace the #1 coil pack for $10 if you guys think I should. Car has 148k miles on original plugs and coil packs.

     
  14. prius4ed

    prius4ed Member

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    So, I guess removing the fuel pump fuse or relay (if there is one) or unplugging the fuel pump and driving the car on the HV battery won’t uniformly deplete the cells. So the guy who sold me the used cells is probably wrong?
     
  15. prius4ed

    prius4ed Member

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    So, I guess removing the fuel pump fuse or relay (if there is one) or unplugging the fuel pump and driving the car on the HV battery won’t uniformly deplete the cells. So the guy who sold me the used cells is probably wrong?
     
  16. bisco

    bisco cookie crumbler

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    if he isnt, it's a new one on me. but ive been wrong before. sounds like an interesting way to kill the battery
     
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  17. prius4ed

    prius4ed Member

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    Maybe I can use a lightbulb or motor and discharge each cell to some expert-determined voltage Before reconnecting them all and driving the car to let it charge the cells (which should be uniform). But catching the motor or lightbulb at the right voltage may be a pain. The time it takes can vary a lot
     
  18. prius4ed

    prius4ed Member

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    On the other hand, driving the car out of gas seems to kill the HV battery in 5 minutes so can I assume you can safely discharge each cell at a rate that only takes 5 minutes to deplete it? As long as I blow cool air over the cell to keep it cool?
     
  19. bisco

    bisco cookie crumbler

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    'hybrid battery rebuilding'
     
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