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I have a model 3 that’s about 14 months old and a little over 12,000 miles on it. A couple months ago I had to have the BCM replaced which took almost 2 months of waiting for the part to come in before replaced. During those two months of waiting, I had some serious phantom draining while the car sat in my garage. I was averaging a loss of 30+ miles a day when typically it’s only 3 miles a day. Yesterday when I opened the door to the car, It started to glitch out and eventually shutting down all power to vehicle. The lights were flickering and the center screen looked like something out of the matrix. I received the message that my 12v battery needed to be replaced. I tested the battery and it read 100% charge with a voltage over 13v. I managed to reset the code by disconnecting the battery under the frunk and also the battery under the backseat. After that the car was running correctly, but this morning I see that the message has reappeared. My question is, could the battery have been damaged during those two months of phantom draining before the BCM was replaced or is there another known problem that could be happening? I love the car, but the issues I’ve been running into in a short amount of time and the fear of being stranded somewhere are starting to outweigh the love.
 
12V batteries have been a problem for 3's recently. Had mine die a month or so ago and if you search the forum you will find quite a few reports. Hard to say if your 12V issue is related to that or to your car's issues.


Either way, you should get it fixed, because it can leave you stranded, sometimes with little to no warning.
 
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Both cars were stranded. We had no warning that the 12v battery was failing. It killed them both. Neither of us have aftermarket installations. We both have the factory sentry mode. Both cars got updates after the new batteries and we both have not had an issue with the batteries since.
 
“Breaking my car”, how can I break something that according to you is already defective? You added a lot to this post, thank you.

You obviously don't know "what you don't know" and have no business touching sensitive electronics and high voltage power disconnects.

Just leave it to the professionals and be patient.
 
Hey @Prometheus that really sucks. :( Make sure you ask them to pull the error log for your car. There might be something there worth looking at. I'm not a Tesla repair tech by any means, but your symptoms sound like you might have a control module going out in your car. There are a few different control modules throughout the car, but that's kinda beyond the scope of a forum post. As you said, it doesn't sound like a 12v battery issue since your battery tested out ok.

Sorry to hear you're having such a bad time with your new car.
 
Hey @Prometheus that really sucks. :( Make sure you ask them to pull the error log for your car. There might be something there worth looking at. I'm not a Tesla repair tech by any means, but your symptoms sound like you might have a control module going out in your car. There are a few different control modules throughout the car, but that's kinda beyond the scope of a forum post. As you said, it doesn't sound like a 12v battery issue since your battery tested out ok.

Sorry to hear you're having such a bad time with your new car.
Thanks, I’ll be sure to do that. Just noticed another issue where the driver side window won’t go up with the app. All the other windows do but that window doesn’t budge.
 
Thanks, I’ll be sure to do that. Just noticed another issue where the driver side window won’t go up with the app. All the other windows do but that window doesn’t budge.
There is a window control reset procedure in the manual, and I used to have it memorized, but then again I can't remember what I had for breakfast. Anyway, doing this procedure will let the controller "learn" where full up and full down is. Try finding that procedure and doing it a time or two. If that doesn't help, then it kinda makes my theory of a bad control module look like more of a possibility.

Tesla used to recommend doing the window position learning procedure after every time the 12v battery is disconnected. Not sure if they still have this recommendation or not.... it's been a while since I RTFM. :D
 
You speak with such confidence, like a know it all. This is a forum for learning, maybe you don’t belong.

I would link you to the battery disconnect manual which has the explanations, but I don't want to encourage you to think that it is a good idea to tinker with the car.

Repairing a Tesla DIY is a big deal beyond any of its mechanical parts that it shares with the ICE cars. You are under warranty, so there isn't even any possible advantage to doing so.
 
There is a window control reset procedure in the manual, and I used to have it memorized, but then again I can't remember what I had for breakfast. Anyway, doing this procedure will let the controller "learn" where full up and full down is. Try finding that procedure and doing it a time or two. If that doesn't help, then it kinda makes my theory of a bad control module look like more of a possibility.

Tesla used to recommend doing the window position learning procedure after every time the 12v battery is disconnected. Not sure if they still have this recommendation or not.... it's been a while since I RTFM. :D
The tech was just here. He said that it all had to do with a recent software update which had him changing out a lot of batteries. The battery I had was no longer putting out the appropriate amps and after replacing it he said he always has to recalibrate the windows. He was in and out in 15 minutes. He did confirm though, that had I not gotten it fixed soon, it eventually would’ve left me stranded.
 
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The tech was just here. He said that it all had to do with a recent software update which had him changing out a lot of batteries. The battery I had was no longer putting out the appropriate amps and after replacing it he said he always has to recalibrate the windows. He was in and out in 15 minutes. He did confirm though, that had I not gotten it fixed soon, it eventually would’ve left me stranded.
So glad to hear it was just the 12v battery!

Man, it seems to me like you've gotten all the crap out of the way early on, and you're gonna have a reliable Tesla from here on out. :)
 
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