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12v Battery Needs Service

Discussion in 'Model X: Battery & Charging' started by xkwizit, Jan 13, 2017.

  1. xkwizit

    xkwizit Member

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    IMG_0489.JPG Just past 9months and 13.5k miles, I guess a combination of cold weather, seat warmers, steering warmer, short trips, dash cam and the mifi was enough to kill the 12v battery :confused::eek:
     
  2. thimel

    thimel Member

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    Call your SC. They will replace it under warranty. This is common and has nothing to do with your electrical usage while using the car. It has everything to do with the vampire draw do electricity when you are not using the car. There are threads about this problem.
     
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  3. xkwizit

    xkwizit Member

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    I thought that the vampire draw talked about in the forums is usually on the main battery that powers the motor not the 12v battery
     
  4. thimel

    thimel Member

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    What happens is the vampire draw is taken from the 12V battery which is periodically recharged from the traction battery. This cycles the 12V battery several times a day which wears it out until it dies.
     
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  5. K-MTG

    K-MTG Sunshade Captain of TMC

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    This makes me worried about my X, I have a 10-15 mile per day vampire drain on my X. And also have a always on dashcam + mifi like the @xkwizit. In addition, I have always connected checked and energy saver disabled.

    Are you gonna disconnect the dashcam + mifi before you take it in? I doubt that is the culprit but the SC might give it the blame.

    Can you still drive the car? Did you call the SC, hopefully they schedule you in ASAP. Please keep us posted
     
  6. xkwizit

    xkwizit Member

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    @thimel - That's counterintuitive. You probably know more than I have been able to dig up thus far. But it doesn't make design sense to me to draw from 12v battery and then charge it from the main battery. Plus the same issue should have happened with my S but its been 18months on that and the 12v battery is working fine. The differences between the two cars are what I mentioned in my original post.

    @K-MTG - Cap Sunshade ..I haven't called in yet due to the weekend but anyways the 12k service is also due. And yeah the car is working fine with that notification on the dash.

    And no I wasn't going to disconnect the dashcam+mifi setup they both get power from the source on the left side of the driver footwell. If they want to blame that, they will need to prove it. It cannot be 100% just those two- I think the seat heaters and type of usage matters. 12v batteries aren't expensive to replace. I don't expect them to make a stink about it at least this time. After all they gave me an extra sunshade last summer (not kidding :))
     
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  7. K-MTG

    K-MTG Sunshade Captain of TMC

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    Wow, an extra sunshade!!! I hope they don't blame the dash cam, but you could simply unplug the dashcam/mifi before taking it in? And leave all the wiring in place. Apparently some SC's unplug dashcam themselves.

    I didn't think this issue is widespread on the X as it is on the S. Is this the first report on the X?
     
  8. thimel

    thimel Member

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    My S needed a new battery after 9 months. YMMV. It takes significant power to run the D.C. To D.C. Converter and monitor it with all the computers. Hence they don't leave it running all the time. There are old threads with lots of information. Search is your friend.
     
  9. xkwizit

    xkwizit Member

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    @thimel - my apologies if it sounded like I was disputing your post..it's just that the whole concept of having a 12v battery seems insane and on top of it this 12v battery renders the car useless lol when you have a perfectly charged bigger battery
     
  10. MP3Mike

    MP3Mike Well-Known Member

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    It is required for safety, you can't have 400V available all the time, so there are big contactors in the HV battery to cut power from the rest of the car. once the HV battery turns off you have to have power from somewhere to power the electronics and ask the HV battery to turn back on. Almost all EVs still have a 12V battery.
     
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  11. thimel

    thimel Member

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    No offense taken. I was just explaining why it is the way it is.
     
  12. neverdone

    neverdone Supporting Member

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    My wife and I are on 7 day road trip to Custer, Devil's Tower and Yellowstone.
    This morning the display shows:
    12V Battery Needs Service
    Replace 12V Battery Soon
    I called Tesla service saying that we are in Custer SD, but will be at the Rapid City supercharger in the afternoon, then to Gillette WY, Billings MO, and West Yellowstone over the next few days. The agent says there is no Ranger in the area but maybe they could send someone from Idaho to Yellowstone. She said to call back later if I had any concerns. I then called Tesla service back around noon and asked if they could have someone replace the battery on Wednesday afternoon when we would be at the West Yellowstone Supercharger. The agent said she would put in the request and that someone would call me back.
    When we were at the Rapid City Supercharger around 4pm, I called Tesla again. This time the agent says I should go to a local auto battery store and get a new battery. He looked up a close battery store and suggested we go to Interstate Battery about 2 miles away. We went to the battery store but I have no idea where is the battery. I called Tesla back and this time the agent said that only Tesla can replaced a battery. I gave the agent the name of the previous agent but still no go.
    This time the agent said the battery display is just a proactive message and that I have at least 2 weeks to get the battery replaced.
    So I guess I will just ignore this blinking message and hope we make it home.
    28765 miles.
     
  13. Brass Guy

    Brass Guy Member

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    This makes no sense, unless that agent thought you were talking about the high voltage battery. I changed mine myself, but I had to get it from tesla. It did not have standard (battery post) connections.
    I understand it's easier in newer models, in an easier place to access.
     
  14. neverdone

    neverdone Supporting Member

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    The Tesla Ranger replaced the 12V battery yesterday.
    Requires the removal of the front trunk.
    Took about 30-40 minutes to replace.
    The 12V battery is an AtlasBX 60B19RS.
    IMG_3195.JPG IMG_3188.JPG
     
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  15. Brass Guy

    Brass Guy Member

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    Aw, that's so much easier than my 2013 S was! And regular battery posts, too!
     
  16. Screwbal

    Screwbal Member

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    I had the battery in my old S fail at 1 year. Haven’t done enough digging to look for a correlation but those who have it die are you using 3rd party data logging where the car is woken up often or just never gets to deep sleep? I was during that first year but stopped after the battery replacement.
     
  17. neverdone

    neverdone Supporting Member

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    I am using TeslaFi; default sleep settings.
     
  18. JUdell

    JUdell Member

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    Well this isnt good. I needed to replace my 12v batter only. Months after they replaced the last one. Tech advisors tell me both are required because I didnt drive my S for 2 weeks at a time. Amazingly, the first question asked of me by the tech was "has the car been sitting for a couple of weeks?"
    When I confirmed it had he advised that I would need to bring it in to replace the battery again! Not so easy when the closest repair center is 250+ miles away! When I brought it in the last time the tech manager (last week) the tech manager advised they are using a "new battery and new system. Anyone know about this or is this just bull.
    I paid $150,000 Cdn for the car 16 months again. I shouldnt need to bring the car in to fix an engineering defect.
    I love my car!!! Come on Tesla. Post something confirming you have fixed the issue!!!!!....or fix it but not at the expense of my time and money
     
  19. dgatwood

    dgatwood Member

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    Just because you're drawing power from the main pack doesn't mean you have to have 480V going to the car. The individual cells are what, 1.2 volts? Deriving a 12V feed from a subset of the pack ought to be downright trivial in any number of ways, from adding extra taps on the pack to adding switched mode regulators that get driven by 400V through an extremely low amperage fuse, or a combination of the above. I'm not convinced that such a design would really be a safety problem....

    But either way, I think the core problem is that lead acid batteries are just entirely the wrong tool for the job. An engineer did some analysis here:

    Syonyk's Project Blog: Tesla Model S 12V Battery Analysis

    and it sounds like the charge circuit (at least in the Model S) is horribly abusive, with spikes that are way above an appropriate charging voltage and charge cutoff timing that doesn't adequately allow the battery to reach a complete charge. Combine that with power consumption that puts an insane number of fairly deep cycles on the battery, and you have a recipe for burning up the plates.

    I think a capacitor bank would be a much better fit for this task. Sure, supercapacitors take more space for a given capacity, but the better ones are also rated for a million cycles all the way down to 0V, whereas lead acid batteries will likely burn up their plates if you do that even once. By my math, a high-quality supercapacitor with even a tenth the capacity of the existing battery would likely last the better part of a century at the same level of charging and discharging, for probably not that much more than Tesla is spending on replacement batteries during the warranty period, though possibly at a small cost in terms of turning on the big battery's output more frequently.

    Am I missing something?
     
  20. MP3Mike

    MP3Mike Well-Known Member

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    You can't just put an extra tap to some of the cells since that would result in an imbalanced pack and cause early failure. Tesla has since put a 12v feed from the HV pack to keep the 12v electronics powered and reduce the load on the 12v battery. So 12v battery failures shouldn't be as common on the cars with the newer HV packs.
     
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