Hybrid battery drained to 0 while driving it and now car won't shift

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by JoeDog99, Sep 21, 2025 at 2:09 PM.

  1. JoeDog99

    JoeDog99 Junior Member

    Joined:
    Jun 29, 2022
    35
    1
    0
    Location:
    Minnesota
    Vehicle:
    2008 Prius
    Model:
    ----USA----
    While driving it drained to 0 bars and i had to pull over quickly.

    I had no dash warning lights prior. I tried disconnecting it and reconnecting it but upon starting the car the hyrbid battery shows 6 bars byt then immediately goes to 0 once trying to shift it.

    12v is good and just tested it.

    Any ideas?
     
    #1 JoeDog99, Sep 21, 2025 at 2:09 PM
  2. pasadena_commut

    pasadena_commut Senior Member

    Joined:
    May 2, 2019
    2,444
    734
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    You need to have the OBD2 codes read. There is a long thread on this site discussing the relative merits of various testing devices for this.

    Gen2 OBD2 app review | PriusChat

    Then report back with that information. In the meantime do not try to go to ready again as it will only further drain the HV pack. Pressing the power button twice (without your foot on the brake!) should be enough to read the codes. If the 12V runs down it is easy to attach a charger to it. Charging the HV pack will require equipment that is hard to come by and/or expensive.
     
    #2 pasadena_commut, Sep 21, 2025 at 2:46 PM
  3. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,731
    8,547
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    If you're driving uphill, it could use more of the hybrid battery. If there is a problem with it, multiple warning lights would come on before it fails. I just think you were probably going uphill and using a lot of the batteries resources and draining it. This could be quite normal due to the age of the battery.

    As for it not starting, did you disconnect the orange disconnect plug on the HV battery? When you put it back in, you have to flip it up and then push it downward towards the floor to lock it into place. If you don't lock it into place, the car will not start
     
    #3 JC91006, Sep 21, 2025 at 2:48 PM
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    113,153
    51,508
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    how fast were you going? was the engine still running when the battery died?
     
    #4 bisco, Sep 21, 2025 at 2:49 PM
    Last edited: Sep 21, 2025 at 2:58 PM
  5. JoeDog99

    JoeDog99 Junior Member

    Joined:
    Jun 29, 2022
    35
    1
    0
    Location:
    Minnesota
    Vehicle:
    2008 Prius
    Model:
    ----USA----



    I did hook the plug in correctly.

    Just now i was able to get it to shift to drive and i put my foot on the break and one on the accelerator and its now at 4 bars and the engine is running.

    But i am not sure i should risk driving it. Is it safe?
     
    #5 JoeDog99, Sep 21, 2025 at 3:00 PM
  6. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,731
    8,547
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    I don't see how it could have a problem, unless you're out of gas

    The car will throw out 3 or 4 warning lights on your dash if the hybrid battery failed
     
    #6 JC91006, Sep 21, 2025 at 3:02 PM
  7. JoeDog99

    JoeDog99 Junior Member

    Joined:
    Jun 29, 2022
    35
    1
    0
    Location:
    Minnesota
    Vehicle:
    2008 Prius
    Model:
    ----USA----
    I have had issues with the dash in the past (back up camera not working, no spedometer) but its been working for the last few months so maybe its just not displaying the lights?

    I was told its just the combination meter for why it acts up sometimes but spedometer and backup camera worked before hyrbid drained while driving today so...
     
    #7 JoeDog99, Sep 21, 2025 at 3:05 PM
  8. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,731
    8,547
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    Yes the combination meter problem will often show the HV battery at 1 bar, that is just an electronic issue. So you should address the combination meter first, before anything else.

    Without proper dash lights, you won't know your gas level or possibly warning lights (although I think those lights are separate)
     
    #8 JC91006, Sep 21, 2025 at 3:09 PM
  9. JoeDog99

    JoeDog99 Junior Member

    Joined:
    Jun 29, 2022
    35
    1
    0
    Location:
    Minnesota
    Vehicle:
    2008 Prius
    Model:
    ----USA----
    They were working today and the last few months but maybe not fully as i assumed

    I will try to drive the 12 miles to home and hope the car lasts.
     
    #9 JoeDog99, Sep 21, 2025 at 3:12 PM
  10. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,731
    8,547
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    I think you'll be fine, if the battery drains down to 1 or 2 bars, it'll self charge. A weak battery will charge and discharge much faster than a healthy battery
     
    #10 JC91006, Sep 21, 2025 at 3:13 PM
  11. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,731
    8,547
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    I actually had a similar situation this week with my 2008. My HV battery would not charge properly and I drove about an hour with the battery meter below half way. This is not normal. I went home to find out my engine was the issue and it was misfiring on 1 cylinder. That misfire prevented the engine from charging the battery properly. No warning lights
     
    #11 JC91006, Sep 21, 2025 at 3:16 PM
(You must log in or sign up to post here.)