Propulsion Battery Compromised

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by jimnjo, May 27, 2019.

  1. jimnjo

    jimnjo Member

    Dec 29, 2005
    2015 Prius c
    I am writing for a friend with a 2006 Prius with lots of miles. Since I am getting info second hand, and probably incomplete at that, please bear with me.

    Recently a bunch of warning lights came on and she got the car to her regular mechanic (not a Toyota place, and certainly not a Prius-trained guy, but has been consistently very good over the many years she has had the car). Apparently it was diagnosed as having a failure in the connections to the main battery, I expect from corrosion. They were reportedly not able to reconnect the "back part of the battery bank" for reasons I do not currently know, but did get it partially connected. Just how these connections are set up is far beyond my experience so I am not really sure just how this looks. The result seems to be that the battery bank will now be only partially charged, or maybe more accurately, only part of the battery bank will be charged. I expect this means the battery bank will run chronically low.

    Since the car is not in the condition that major, expensive repairs make sense, and also since she just wants this car to limp through the rest of this year before replacing it next winter, the question becomes...Can one simply live with this problem for a while? I assume mileage will suffer considerably, and any potential salvage value of the battery bank will be compromised. Neither of these are a deal breaker for living with it. Are there other concerns or implications that are more immediately problematic?
  2. ericbecky

    ericbecky Hybrid Battery Hero

    Mar 12, 2004
    Madison, Wisconsin
    2005 Prius
    Not sure what they mean by back part of the battery bank.

    The car needs all portions of the battery in order to be at the correct operating voltage.

    You can't just skip part of it.

    It will not be able to run unless all portions are properly connected.
  3. fotomoto

    fotomoto Senior Member

    Apr 22, 2009
    So. Texas
    Other Hybrid
    Prepare for the worst, hope for the best.

    Without codes, we're just guessing. A competent mechanic has a pro-level code reader so they will have access to the hybrid specific codes.

    On to the guessing, my first thought is the original HV battery has finally died. If so, she can look into (cheapest to most expensive): battery repair, battery replacement with used (refurbished) pack, all new cells, or new Toyota battery. Hoping for the best? Maybe just a wiring harness issue due to corrosion (very thin sensor wires can break).

  4. exstudent

    exstudent Senior Member

    Jul 11, 2009
    Torrance, CA
    2007 Prius
    NO! She will most likely be left stranded one day in the immediate near future. The car will refuse to budge.

    The car is a computer, trying to optimize MPG and protect itself. Given the current condition, the car already knows it is in trouble, and will now be trying to protect itself from the owner.

    The car is just worth salvage value to a junk yard. A couple hundred????

    I think she might get more money by listing it one sale here (Prius Cars For Sale | PriusChat). A hobbyist/DIY enthusiast would probably buy it from her, if the HV Battery is the only problem.

    What does she consider "expensive"?
    • A module swap might cost $100/module; but is a very temporary solution; not unheard of for such a band-aid repair to go bad in days/weeks AGAIN.
    • A competent HV Battery rebuilder might charge <$1k; competent people/companies are rare, plenty of hacks selling their services/products though.
    • member "2k1Toaster" sells new cylindrical module replacement; it will be a NEW HV battery; $1600 shipped, New Prius Battery Kit (GEN2, 2004-2009) - New Prius Batteries LLC
    • 100% new OEM, HV Battery could be had for $1599 (Nov 2018), does NOT ship, need to find a dealer who will sell to you; read post #9 & #11.
    She should start shopping for a NEW/new-used car now.