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New 2024 Prime XSE, 12V battery dead 4 times in 18 days... dealer admits it's a known problem.

Discussion in 'Prime Technical Discussion' started by MGBear, Sep 13, 2024 at 9:39 PM.

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  1. MGBear

    MGBear New Member

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    2024 Prius Prime
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    XSE Premium
    My GF just purchased a beautiful red 2024 Prius Prime XSE Premium, new. During the first 175 miles and 18 days the 12v battery has failed 4 times, having to be jumped each time. It has been taken back to the dealer 3 times. I have made sure not to jump the car myself, to avoid giving the dealer something 'we did' to blame the problem on. Their explanations:

    1: "Oh, you must have left the lights, or something on".

    2: "Oh, you didn't drive the car long enough or fast enough after jumping it (drove it for 30 minutes as instructed by the roadside service guy). The battery was low, so we gave it a full charge."

    3: "Oh, the battery was actually defective, so we replaced it."

    Then, finally....

    4: "We brought the Toyota engineers into the mix. The engineers said it is a KNOWN PROBLEM with cars coming from a particular factory. The car's internal wi-fi system does not shut off while the charging cable is plugged in. The only solution currently is to disable the 'Toyota Connect' system/services." This means, no remote app connection, no Toyota GPS mapping, etc. So you can't control/monitor charging remotely, anything that you would use the app for. They disabled all of the above , and the problem has not repeated (though we still only have around 200 miles on the car) They said "We'll let you know, if and when there is a fix to this problem." (!!!) Until then, the car remains neutered.

    It is absolutely absurd that these features must be disabled just to make the car reliable enough to start every morning. That is NOT a solution. It's equally absurd to jump through the work-arounds that that others have had to come up with just to get a BRAND NEW car to behave the way it should be expected to by design. One shouldn't have to baby and troubleshoot a NEW, high technology car every time it is driven. One shouldn't have to ask "Did I drive it far enough today?, or else be faced with a dead car.

    My GF was SOOOO excited to get this car, it was exactly what she wanted after much research. She drove a hard bargain to get a reasonable price. Now she just wants to cry.... this bad taste has taken so much joy out of the experience.... spontaneous joy that is permanently lost, even if we do resolve the problem.

    We know that there is the California Lemon Law option, but we don't want to go there, if avoidable. We just want her to have this exact car, just functioning as advertised.

    Before deciding on this car, we watched lots of YouTube videos, all very positive. I think now it's time to make my first YouTube video to warn the general public of the potential crap-shoot you are exposing yourself to in buying this otherwise wonderful car.

    Any comments on similar experiences are welcomed.
     
    #1 MGBear, Sep 13, 2024 at 9:39 PM
    bisco likes this.
  2. schja01

    schja01 One of very few in Chicagoland

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    Has the 12v battery actually been replaced? If the battery has been totally depleted due to sitting on the dealer lot for weeks or similar it could be damaged to the point where it needs replacement. Dead 12v batteries on Primes is more common than Toyota seems to want to admit. I would think a solution would have been implemented by now.
     
    #2 schja01, Sep 14, 2024 at 6:26 PM
  3. bisco

    bisco cookie crumbler

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    search here for several threads on this problem. i thought there was a software update fix
     
    #3 bisco, Sep 14, 2024 at 8:18 PM
  4. KMO

    KMO Senior Member

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    There is a TSB for charging battery drain, but that's the first time I've heard it related to the Connected Services.

    TSB info on this post:

    Parasitic battery drain? | Page 4 | PriusChat

    Make sure they've performed that update.

    Wonder if it really is related to the Connected Services stuff - I've not signed up for any of that, and haven't had any problems, for one data point, but then I imagine most people haven't had any problems.

    Has anyone not using Connected Services seen a depletion problem?
     
    #4 KMO, Sep 15, 2024 at 4:48 AM
    bisco and BiomedO1 like this.
  5. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    How does she feel about putting a battery maintainer in the trunk area and charging the 12 volt battery?
    I am sorry to repeat it a hundred times but get a battery monitor on the 12 volt and she can see how it’s doing on her phone when driving, or not driving. If it’s low, charge it.
    Many brands of ev and hybrid cars have a 12 volt going dead problem, forums are full of them. Even new non hybrids have more things turned on than cars of yesteryear. One thing may be the stop start button use, although there are warning chimes about leaving the car on and getting out.
     
    #5 Mr.Vanvandenburg, Sep 15, 2024 at 1:05 PM
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  6. BiomedO1

    BiomedO1 Senior Member

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    I would take the car to another dealership, to check the other dealership's work. The car's under warranty, verified through VIN - warranty is valid through ANY Toyota dealership.
    1. The battery is only getting a charge while the traction battery is charging. If the car is plugged-in and not charging - The starting battery is NOT getting a charge. In fact the battery is getting discharged at a higher rate because it knows it's plugged-in and is constantly doing a status check. OM states to disconnect the charging cable when finished or car isn't charging.
    2. There is a TSB and software update, perhaps someone missed it - but the software revisions need to be check to ensure you've got the latest software.
    3. OBD2 socket - anything that gets plugged into it becomes a parasitic draw (ie. Metromile or other insurance discount dongles). There's a direct power cable back to the battery on that socket. Pretty much all aftermarket electronics installers are told to go after that wire. The wires going back to the main wiring harness needs to be traced - to see if someone hung some parasitic electronics on there. Dealerships install tracking modules to lower insurance cost. This is like leaving the dome light in your car ON all the time. Oh, check you vanity mirror lamp is OFF.
    4. If all else fails, clear out your trunk - so a technician has clear access to you battery. Take the car to any automotive parts store for a free battery test. If you don't know where it is, this is a good time to find it in your OM.

    Hope this helps....
     
    #6 BiomedO1, Sep 15, 2024 at 2:51 PM
    Last edited: Sep 15, 2024 at 2:57 PM
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