Hybrid battery - how bout just changing bad cells without "reconditioning"?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Andrew Vanis, Jul 22, 2025 at 12:12 AM.

  1. Andrew Vanis

    Andrew Vanis Junior Member

    Joined:
    Jul 7, 2018
    17
    5
    0
    Location:
    Albuquerque
    Vehicle:
    2005 Prius
    Model:
    N/A
    Hybrid battery - how bout just changing bad cells without "reconditioning"?

    I have 2 batteries. one bad cell #7 one bad cell #13 per Dr Prius.

    Cold I just take a good cell #7 from the one with bad cell #13 and put the not-bad #7 into the one with bad cell #7?

    Ideally I would do a complete "reconditioning" like the instructions listed here - DIY hybrid battery reconditioning - where/how to start | PriusChat

    and really since I don't have a battery charger and just want to move the car now, how bout just changing bad cells without "reconditioning"?

    Thanks
     
    #1 Andrew Vanis, Jul 22, 2025 at 12:12 AM
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,677
    8,521
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    You're better off buying a complete used battery and replace the one you have. The way you're thinking about doing it, it won't last long and with all the work involved in doing it, it might just be worthwhile to do it correctly the first time or don't do it at all. It'll be a waste of time and the problem will come back again real soon
     
    #2 JC91006, Jul 22, 2025 at 12:54 AM
    Brian1954 likes this.
  3. T1 Terry

    T1 Terry Active Member

    Joined:
    Jan 4, 2015
    765
    407
    0
    Vehicle:
    2006 Prius
    Model:
    Plug-in Advanced
    The major problem is the stuck pressure release valves in each module pushing the electrolyte out through the terminal seals. The electrolyte needs to be topped up, the pressure valves feed and the module links cleaned and voltage sense wire harness replaced .... along with checking the pin stick out in the battery computer module ..... all in this post here https://priuschat.com/posts/3551878/ How to top up the electrolyte, the mix ration and how to release the pressure valves is in a thread about rehydrating battery modules Re-hydrating the battery modules. | PriusChat

    T1 Terry
     
    #3 T1 Terry, Jul 22, 2025 at 12:57 AM
  4. Brian1954

    Brian1954 Senior Member

    Joined:
    Jan 31, 2021
    1,853
    730
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    How far do you want to move the car? If it is not very far, you should get able to do it with the hybrid battery that is in the car.
     
    #4 Brian1954, Jul 22, 2025 at 8:20 AM
  5. Andrew Vanis

    Andrew Vanis Junior Member

    Joined:
    Jul 7, 2018
    17
    5
    0
    Location:
    Albuquerque
    Vehicle:
    2005 Prius
    Model:
    N/A
    Thanks for the replies. Specific replies below.

    Generally, I'm wondering if there would be any harm in my approach (replacing a shown bad cell with a shown not-bad cell) and/or if it might get me 80% there...then I could do the 100% as I have more time/interest/resources....and I'll have the rest of the cells in the left-over battery to replace into the battery that I'd be using to either replace other cells that go bad or to optimize them.

    The car has its battery removed so I have the 2 batteries on the bench (to recap, one has bad #7 one has bad #13

    I don't mind pulling / installing the hybrid battery, its the inside work I don't yet have experience with....and since I have it out, want to see what mostly-there options are available for the bad cell w.o diving into a full reconditioning.

    and to answer your specific question, move it from my front yard to my back yard around the block...but really, If I put the orig battery in It'll probably stay in there until I do a full recondition - though the thing I'm trying to achieve is getting a working battery in there long enough to determine what else the car needs so I could also do those things while the car in immobile while reconditioning the battery..

    It'll be interesting what I find when I open these up. One is a Dorman replacement "just out of warranty" and one is a 3rd party company Toyota refurbished.

    what it seems in the multitude of pages in this pressure valve/electrolyte thread you linked is that it really not figured out yet...thus, back to my "replacing a shown bad cell with a shown not-bad cell" inquiry.

    Considering your post count I heed your advice "It'll be a waste of time". I know it I choose this I might not get much out of it...mainly wondering what to look for/consider in the only-cell-swap approach since I'm not going to do a full recondition right now.

    Thanks again for the replies and look forward to your additional thoughts.
     
    #5 Andrew Vanis, Jul 22, 2025 at 11:53 AM
  6. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    112,467
    51,184
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    some have had good luck just replacing bad modules with good, but it's a minority for sure.
    there are too many factors involving the remaining modules to know if it will last very long or not.
    if you just want to move the car, it should work, but won't disconnecting the 12v to reset the codes do the same thing?
     
    #6 bisco, Jul 22, 2025 at 2:40 PM
  7. Andrew Vanis

    Andrew Vanis Junior Member

    Joined:
    Jul 7, 2018
    17
    5
    0
    Location:
    Albuquerque
    Vehicle:
    2005 Prius
    Model:
    N/A
    For about a 1/4mi code clear works I'd like to get a couple tanks through at least giving it a good drive. The PO said he got an O2 code and maybe some others so would be great to get my own list of codes so I could see all the things it might need and do then while reconditioning the battery.
     
    #7 Andrew Vanis, Jul 22, 2025 at 2:47 PM
    bisco likes this.
  8. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    12,076
    4,902
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    I always explain that if it's the first bad module on a pack that's never had a problem before you can buy a high quality replacement module for $35 and put it in and get lucky for a year. Plenty of people have done that. Of course myself and others sometimes barely get a few miles down the road before warning light come back on doing that.

    As in each module you replace the more problematic the pack is going to get. However if you have access to lots of modules and you recondition and test them and match up modules of similar performance you can get several years from a rebuilt pack.
     
    #8 PriusCamper, Jul 22, 2025 at 6:33 PM
(You must log in or sign up to post here.)