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12v battery issue, Tesla unsatisfactory response

Discussion in 'Model 3' started by Tjhappel, Sep 19, 2020.

  1. CertLive

    CertLive Member

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    Well it seems there is some sort of issue here and it also seems that 2 years for a 12v battery to die is quite bizarre. So in that light compared to other cars on the road its an early failure. Unless its a very cheaply made battery with a bad reputation? Not all is created equal but 2 years is not good enough. 300 posts is quite a large and well thought out issue. Look at brilliant investigation going on by engineers. Good luck getting the real 12v failure rate figures but if its 1 or 90,000 cars it is not good enough. Not if you compare it to ice EV will replace. Even saw a video yesterday of the new VW ID 3 lose its battery power after 5000 miles.
     
  2. CertLive

    CertLive Member

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    So its fair to say 2 years would be a bit premature but so far so good with the 3.
     
  3. neurocutie

    neurocutie Member

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    good to know, that says it right there... when the whole world is moving or already using ARM...do they develop on Macs perhaps? (going to ARM as well...) Hope Nvidia doesn't botch things up...
     
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  4. EnrgyNDpndnce

    EnrgyNDpndnce Member

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    There’s no doubt early failures are bad and of course Tesla should replace those that fail within the 4/50k warranty period. The question is, what is the early failure rate and how does that compare to industry standards. To read some of these comments you would think no other car has ever had a 12V fail in less than 2 years which of course is absurd. So if Tesla has 1 in every 50k cars experience an early 12V failure and the industry norm is one in every 500k cars, well then Houston we have a problem. If however the early failure rate in Teslas is relatively close to that of the industry, then nothing to see and move along. My point all along is that we don’t have any of that data and all of these posts suggesting this may be a major issue are premature. Once we have some data we can have a more informed discussion.
     
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  5. FalconFour

    FalconFour Supporting Member

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    I'll add my anecdata as well:

    3 LEAFs from 2012-2018 - one replacement battery but I milked the hell out of my 2013 Leaf up 'til it was totaled - it definitely should've been replaced as I kept a 12v jump-battery with me and used it about once a month when it died. My analysis of how it was using the 12v battery was simply that it likely had a FW bug that unpredictably left some system running after shutdown (maybe 1 in ~100 shutdowns), causing it to be killed unexpectedly - and it didn't fully charge it, leaving it in the mid SOC range its whole life, presumably for the SL trim's solar panel to recharge it (mine was an S - it didn't have that solar panel). Solidly in the realm of "design flaw" as 2014+ seems to have fixed that.

    Model 3 LR/RWD from mid-2018 to today: its 12v battery performs as good as new (by bench test) up 'til Aug 2020, but I replaced it with a lithium battery just on opportunity.

    The Tesla-based RAV4 EV also seems to have 12v issues, which just goes to play into that EVs just seem to have weird 12v battery management issues in general. Hard to understand why that's the case given the giant main battery they carry around.

    As to sustainability, I honestly think the only reason EVs even use lead 12v batteries is that they're the only remaining useful application for large amounts of lead... and they're usually highly recyclable (much like aluminum cans). So it's kind of a closed loop system, and if a major automaker started to forego lead batteries, I dunno... maybe there'd be a surplus of lead nobody is using?
     
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  6. FalconFour

    FalconFour Supporting Member

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    OK, here's the first couple days of data with the 12v battery logger. It has a hell of a problem with saving/storing the chart data, though, so it's been tough, but it seems like charts come out clean in the end. (just can't view the historic charts 'til the next day for some reason). It also never seems to think the battery is doing anything but charging - even when the car is asleep and it's definitely not charging, it's discharging. It's basing its idea of "charging" on voltage level, which isn't quite right for a lithium battery...

    So here you go, my lithium battery behavior.

    [​IMG]
    This was also doing an update, too... starting at 16, and likely just before the 17 mark was where it rebooted and used the battery briefly, then it went back to sleep at 18. Before that, I'd been driving it a few times throughout the afternoon.

    [​IMG]
    Today, so far. Note that combined with the previous chart, that's at least 12 hours of uninterrupted sleep.

    Note the spike in today's chart. The spike doesn't represent the time it was awake - I was sitting in the car for a good couple hours (from about 11:45 to 14:00) driving and later watching YouTube at home in the car. So, that long lead-off after the spike is actually while the car is awake, choosing to bring the voltage down there. Also note it rests higher than the sleep voltage. So, that seems to be its choice to keep it at that specific voltage... also, what's up with the steps in the Y axis? 9.0v (+2) 11.0v (+1) 12.0v (+1) 13.0v (+2) 15.0v... makes it kinda hard to read, but oh well. Point is, the car was awake there ;)

    It completely lines up with my observations as well - the car sleeps peacefully for hours and hours until I wake it, and generally for no other reason.
     
  7. lUtriaNt

    lUtriaNt Member

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    photos dont show mate...
     
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  8. FalconFour

    FalconFour Supporting Member

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    oh you have to be sh^ttin me. I use "Copy Image" and Ctrl+V out of Google Photos and the thing pastes it as a URL? (so obviously only I can see the images, which look fine here!) First emojis don't work, now this o_O I really wish this forum would use Discourse instead -_-

    Let me try proxying it through mspaint instead, then. I can't edit after a certain time (THANKS, CRAPPY FORUM SOFTWARE) so I just have to repost.

    Once more, my lithium battery behavior:

    upload_2020-11-4_19-18-31.png
    (which currently looks like a "broken image" icon but with an attachment now on the post)
    This was also doing an update, too... starting at 16, and likely just before the 17 mark was where it rebooted and used the battery briefly, then it went back to sleep at 18. Before that, I'd been driving it a few times throughout the afternoon.

    upload_2020-11-4_19-19-41.png
    (which also looks like a "broken image" icon right now as I write this)
    Today, so far. Note that combined with the previous chart, that's at least 12 hours of uninterrupted sleep.

    Note the spike in today's chart. The spike doesn't represent the time it was awake - I was sitting in the car for a good couple hours (from about 11:45 to 14:00) driving and later watching YouTube at home in the car. So, that long lead-off after the spike is actually while the car is awake, choosing to bring the voltage down there. Also note it rests higher than the sleep voltage. So, that seems to be its choice to keep it at that specific voltage... also, what's up with the steps in the Y axis? 9.0v (+2) 11.0v (+1) 12.0v (+1) 13.0v (+2) 15.0v... makes it kinda hard to read, but oh well. Point is, the car was awake there ;)

    It completely lines up with my observations as well - the car sleeps peacefully for hours and hours until I wake it, and generally for no other reason.
     
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  9. Tjhappel

    Tjhappel Member

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    Just say that out loud again in a mirror.... you had to educate a worker at a professional shop!! Wtf do you expect a “normal”person to do?? Read 17 pages of this *sugar* and then go educate a kid???
     
  10. Tjhappel

    Tjhappel Member

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    Agree totally... instead of educating “kids” at oreilly autoparts who “haven’t heard of a Tesla” maybe tsla could tell them what battery they use??? Seems easy enough
     
  11. Tjhappel

    Tjhappel Member

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    Great write up
     
  12. Tjhappel

    Tjhappel Member

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    How about a warning so we can actually fix them before they go bad??
     
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  13. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Looks like it'll probably wake up once or twice a day.

    Probably a non-linear scale just to make it easier to see the regions of interest (counteracts the voltage vs. capacity curve which is somewhat non-linear).

    Your voltages look a bit different than mine, presumably due to the different battery type. That may also alter the amount of time between wake/sleep cycles. I'm curious what the longest sleep cycle you can get is. The longest I've seen is about 24 hours.


    IMG_8234.PNG
     
  14. FalconFour

    FalconFour Supporting Member

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    Well, I'm probably not going to be able to get you that, because I end up using the car at least once a day ;) But it's a stark contrast to what you posted earlier, where it was waking up at least once every hour (just on the last page)... really just posting mine in response to that, making sure I'm not crazy in seeing that mine only wakes up when I make it wake up.
     
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  15. thewallaby

    thewallaby Member

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    #355 thewallaby, Nov 5, 2020
    Last edited: Nov 5, 2020
    I think the only solution would be that Tesla had a parallel charger to the main one or an inverter that topped off the lead battery when charging the vehicle. On my ICE i have a coupe heater that also tops the battery every time i plug it in overnight in the winter. It cannot be so hard. Or even a drop down transformer so when the lead is too low to top off from the main battery. I know that most of you will press the fact that you need this and that special equipment but the man wants to go to Mars in 2 years i bet he can fix that in a weekend...
    Also i do not get why have a 1000 pounds main battery and skimp the weight on the 12v when you 1. 90% of EVs have issues with them and 2. you have the space and power in the frunk to accomodate a much larger.
    All my ICE cars had from 90-120A 12v batteries. Even the hybrid i had until last August it had a 95A battery.... what a place to save weight and money... safety.
    Also why not pick a standard 90A gel battery that will last longer, will be easier to acquire, will be cheaper to produce than a special one and anyone could do it themselves by visiting their near auto shop. I know that they did not do anything on the facelift 2021 but i truly hope they make that change in the future, independently of the software patches or not.
     
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  16. iwannam3

    iwannam3 Member

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    Did a Y test drive and picked up an $85 at Tesla service. No core charge!
     
  17. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Yeah that issue was caused by Stats, which I have to stop using now. It hasn't always been this way, but apparently it is now. The developer says it is normal. Oh well. Have to dump the 3rd party app, though I liked opening my frunk without using my phone.

    The overall pattern I see when Stats isn't involved is consistent with my prior posts of battery drain and how much the 12V gets cycled. (The answer is: a lot!)
     
  18. Phlier

    Phlier Bluebird

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    Alan, once again I find myself agreeing with your post, but there is something that we should probably discuss... in passing, at least.

    I'm old. And I've lived in the desert for the vast majority of my life. Put the two together, and you have the perfect recipe for being a major consumer of vehicle batteries.

    Yet in all my years, I've never seen a car lead/acid battery just out and out fail like we've seen with so many Tesla lead/acid batteries. The typical failure mode I've seen is that the battery just can't contain as much energy as it did when it was new, nor can it deliver that energy at the same rate. In a lot of the failures we've read about here (and other places on the 'net), people explain that their battery failed with a large bulge in it, and with a strong sulfur smell. The result being a battery that was *completely* dead. Not reduced capacity, not reduced ability to deliver energy, but doornail dead.

    I can see Tesla using the battery outside of the battery's design parameters, but to me, that would just mean premature degradation of the battery, and not an out-and-out dead short, failed battery.

    Sure, you also do hear of guys reporting that they got the "replace 12v battery soon" message, along with batteries that have shown "normal" failure modes of reduced capacity and reduced ability to deliver energy. But the rather large amount of posts by people with failed batteries is just a bit suspect.

    I have no proof of this, but to me this reads as a rather large batch of bad batteries produced by the OEM.

    Even if Tesla hasn't been using the 12v battery correctly, I think the OEM needs to man up a bit here.
     
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  19. Phlier

    Phlier Bluebird

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    Please don't take this as me just being pedantic to be a jerk, but there is a pretty significant difference between the Tesla 12v battery and a typical ICE 12v battery.

    The battery used in Teslas is a "Deep Cycle" battery, whereas normal ICE vehicle batteries are designed to deliver a huge amount of starting current for a short period of time, deep cycle batteries are not designed to handle large amounts of current demand, and instead are designed to hold a large amount of total energy, which is delivered at a slower rate.
     
  20. Daniel in SD

    Daniel in SD Well-Known Member

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    I agree the type of failures is abnormal. Of course the usage is also abnormal. Most ICE batteries hardly get cycled at all.
    A hypothesis I like is that to save money on AGM batteries Tesla used a custom design optimized for their use case and the common failure mode can't be detected in advance.
     
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