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12V Battery Died after a surprisngly short time...

Discussion in 'Prime Main Forum (2017-2022)' started by stevepea, May 3, 2020.

  1. outoftown

    outoftown Member

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  2. mveras1972

    mveras1972 Member

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    That, my friends, is what I mean by having to jump through hoops when you could’ve had an emergency override button. Seems that having an emergency jumpstart pack is the way to go if you have a Prime. I ordered a Lithium Ion pack from Amazon. They are nice and small to fit in the glove compartment and last over a year fully charged. You never know when you’re going to be in that situation.


    iPhone ?
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    The nature of the Prime? D'know about that, any car sitting a long time can run down the battery.

    Good plan.
     
  4. mveras1972

    mveras1972 Member

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    [mention]Mendel Leisk [/mention] a week or two sitting unused is not a long time for most cars. I also own an older non-hybrid car (Avalon) which has been sitting for 4 weeks and more unused and this has never been a problem, and let’s not mention the Avalon battery is quite old.

    For the Prime, it seems that a week or two is too long so Prime owners need to be mindful of this more so than owners of other type of car.


    iPhone ?
     
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  5. bisco

    bisco cookie crumbler

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    prime seems to have a larger quiesnt draw, and you cannot shut off sks without dealer. though it does shut itself off after 5 days of non use.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    You can check the amp draw. Maybe the bees knees technique would be a clamp meter? I just used a regular meter, in series on the neg side.
     
  7. schja01

    schja01 One of very few in Chicagoland

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    D8909BC0-94B3-449F-8B89-3BFBEE54F31D.png
    I am 99.9% sure you can disable Smart Kay via the FOB. I am not in a position to check the manual right now. It’s a sequence of lock unlock operations.
    EDIT: I found the procedure. Interestingly the manual even mentions the 12volt drain issue when car is not in use.
     
    #27 schja01, May 6, 2020
    Last edited: May 6, 2020
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  8. bisco

    bisco cookie crumbler

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    that would be great. salamader posted his o/m in the 12v testing thread, and couldn't find it.
     
  9. jerrymildred

    jerrymildred Senior Member

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    Yes and no. Here's what my manual says.
    There's a lot more about the system and it's all rather convoluted. I take this part to mean that the smart key system shuts itself off if unused long enough. The section on customizing says that you can have the dealer turn it off completely. (Or, of course, do it yourself with Techstream, Carista, etc.)
     
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  10. bisco

    bisco cookie crumbler

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    5 days would be fine, if the battery didn't drop a volt by then
     
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  11. Salamander_King

    Salamander_King Senior Member

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    My understanding is that the bottom half of manual you posted is to disabling the fob to save battery in the fob. It dose not disable the SKS system in the car. If you look up the customization part of the manual it clearly state to turn off the SKS system you have to visit a dealer (or maybe DIY with Techstream or Carista).
     
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  12. bisco

    bisco cookie crumbler

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    i wonder if those are the same instructions as gen 4. a lot of peeps think it shuts off sks
     
  13. jerrymildred

    jerrymildred Senior Member

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    That's why I made the comment that the manual is convoluted. Actually, it's just plain unclear. But yes, it looked to me like "Electronic Key Battery-Saving Function" meant saving the battery in the electronic key (FOB).

    But the part above that ("Battery-Saving Function") looks like it is for the FOB and the 12V and is automatic after a period of non-use. Or you can turn it off all together with Techstream or some other OBDII tool. But that's pretty inconvenient for frequent use.
     
    #33 jerrymildred, May 7, 2020
    Last edited: May 7, 2020
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  14. Salamander_King

    Salamander_King Senior Member

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    Yes, that's how I understood it.

    My question would be if you turn off the SKS (via dealer, Techstream, or Carista) would that mean locked car can be opened only by physical key and starting the car will require holding the fob against START button, just like in case of dead battery in fob? What doesn't make sense is that I thought the START button itself is a part of SKS, if the car's SKS is totally shut off, how would it recognize the fob???

    Also for the automatic SKS shut off feature after 5 days of inactivity, I don't know how the car responds to the fob on 7th day??? I have been parking my car for 1 week at a time and driving only once/week, but so far I have not had any problem using the fob to unlock or start the car on 7th day.
     
    #34 Salamander_King, May 7, 2020
    Last edited: May 7, 2020
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  15. bisco

    bisco cookie crumbler

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    i think the fob buttons still work. sks is the tech for touchless activity, which is constantly draining the 12v
     
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  16. Elt31987

    Elt31987 Active Member

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    The vehicle should check for any HV open circuits before opening the relay to allow the HV battery to come online. I would imagine the 12v powers the computers to monitor and check for these conditions. If there was an override button to connect the HV relay you would risk sending HV through the metal of the car if there was a short.
     
  17. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    I don't know exactly how this is all programmed, but as I understand it all, the SKS system is continuously transmitting looking for a response from a fob with the proper encryption key. This also means that the receiver in the fob has to be continuously on, looking for the signal from the car. Magic button presses on the fob can turn off the fob's receiver and stop the drain in the fob, but that does not effect the car.

    OTOH, the old-fashioned buttons on the fob transmit a signal to the car only when pressed, and otherwise the fob is completely off (apart from the SKS functionality above), and all that is needed in the car is a receiver listening for the signal from the fob, which consumes very little (but some) power from the 12v battery.

    Another source of drain in the 2017-2019 Advanced is the SafetyConnect cell phone, which is always on for the telematics (remote apps).
     
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  18. Salamander_King

    Salamander_King Senior Member

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    That drain source applies to all 2020 PRIMEs LE, XLE, Limited, all of which come with Safety Connect standard. Unless, you elect to turn that option off as I did by deliberately declining free 3 years of Safety Connect service.
     
  19. jerrymildred

    jerrymildred Senior Member

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    My theory is that the SKS system involves not having to take the fob out of your pocket. If you have to press the buttons or hold it near the start button, that's not SKS. I could be wrong. I never found anything about that in the manual, but it seems logical to me.
     
  20. Salamander_King

    Salamander_King Senior Member

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    That explanation echoes what @bisco and @CharlesH described. I am satisfied with the explanation. Thank you all.
     
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