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Model 3 12v battery dead

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Tried a smart lithium pack and the tow truck guy tried a huge dumb pack, neither would work. I assume the battery was just pulling too much and the DC to DC was balking. We did not try completely removing the 12v but that's a good idea in a pinch. I've read there can be issues if the jumper pack is too smart and doesn't provide continuous voltage. I think they said the DC to DC has to see over 9v for a bit for them to close.
 
Hey everyone, this morning when I got into my car, the display would not turn on, the front headlights were weak and blinky, and when I depress the pedal, it makes this really weak motor noise. Also the button to unlock the car makes a really weak sound, and rolling down the windows is very slow and weak. Is this a sign of 12v dead?

Also, what is best course of action. Is it to open service request/contact service center, or to call roadside assistance? Thank you.
 
12v is likely dead. IF you need the car soon do roadside, if you want to take a shot and don't need the car soon you can try doing a mobile service.
I see. For roadside I can call the roadside number, but what about how to reach mobile service? I had to Uber to work today, so I'll probably have to take care of it tomorrow. Is this better for mobile service?
 
Won't the car with all its technology warn you ahead of time that the battery is dying and will need to be replaced soon? My $50 UPS does that, surely my Tesla can do it too?
yes and no. It can detect abnormal voltage drops but unfortunately with the nature of the battery and how generally low amps the car pulls the voltage drop is usually minimal before it goes dead. I certainly know mine went from fine one day to dead the next.
 
yes and no. It can detect abnormal voltage drops but unfortunately with the nature of the battery and how generally low amps the car pulls the voltage drop is usually minimal before it goes dead. I certainly know mine went from fine one day to dead the next.
I think based on all the learnings from the members, it is best to proactively replace the 12V battery before it fails. Most of the deep cycle batteries last anywhere between 2 to 4 years, also we don't know how long the battery sat in the lot before it was mounted in the car and shipped out. Tesla will not pay for replacing the battery under warranty unless it fails or it gives a battery warning , which they can see in the cars fault log. So if you are planning to go on a long trip and your car is more than 24 months old, and if you want to buy the peace of mind and not ruin your trip, you may consider replacing the 12v battery proactively. This is a specialty battery and you can't buy it in the regular auto store- hence please keep it in mind when you travel outside Tesla service areas.
 
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Just for a bit of information to yall, the reason people aren't getting warning before their battery fails is because it is an abrupt failure of cells. If a batteries max charge started going down you would get a warning but the fact that people are at 6v tells me that 3 of the 6 cells failed. It isn't a capacity issue. There is no way to absolutely know a cell would outright fail. On ICE vehicles you test the CCA which basically tests battery capacity, but it still doesn't tell you if a cell will fail soon. A 12 volt battery is made up of 6 2.1 volt cells wired in series giving you 12.6 volts. Voltage will be the same even if the capacity is lower, but when you all the sudden drop 6 volts, it is almost always failed cells. On a 12 volt battery 11.9 volts is almost completely discharged(aka - dead). You won't normally get down to 6 volts without failed cells. Failed cells will drop by 2.1 volts per cell failing. When a cell fails, there is more strain on other cells, causing them to fail.

Dead batteries is an issue among ALL vehicles and will leave you stranded in ALL vehicles. if you "jump start" your tesla it should drive fine as the 12v would be charged while driving just like any ice vehicle is when you jump start them with a dead battery.

Source - Me, a fully certified Ford mechanic. As well as partially certified Cummins, International, Cat mechanic. I worked on anything from small cars (including hybrid) up to semi trucks

one thing to add, yes, 2 years seems to short, but really it is pretty standard for OEM batteries. I can't tell you how many batteries I was replacing on 1-2 year old cars and I don't even live in a cold environment where that is a standard issue. One of the aftermarket solutions would most likely last longer if it is quality made. OEMs take the lowest bid for their battery manufacturers, thus made the cheapest. There is a reason ford uses the brand name FoMoCo for factory batteries but will not sell them to people with a warranty afterwards. They are made cheaper than the Motorcraft branded batteries.
 
I think based on all the learnings from the members, it is best to proactively replace the 12V battery before it fails. Most of the deep cycle batteries last anywhere between 2 to 4 years,
I got zero warnings, have about 25k miles. My car was manufacture in October 2018, so, almost three years. Guess I have to make it a 2 year maintenance habit, then.

I am going to try jump it, let it stay awake tonight with summon standby or sentry, and drive to service center tomorrow to replace. Otherwise will have roadside tow to service center.
 
I think based on all the learnings from the members, it is best to proactively replace the 12V battery before it fails. Most of the deep cycle batteries last anywhere between 2 to 4 years, also we don't know how long the battery sat in the lot before it was mounted in the car and shipped out. Tesla will not pay for replacing the battery under warranty unless it fails or it gives a battery warning , which they can see in the cars fault log. So if you are planning to go on a long trip and your car is more than 24 months old, and if you want to buy the peace of mind and not ruin your trip, you may consider replacing the 12v battery proactively. This is a specialty battery and you can't buy it in the regular auto store- hence please keep it in mind when you travel outside Tesla service areas.
You can buy a Group Size 51R battery at pretty much any auto parts store (and many big box stores). That's a direct replacement for the 12v battery in the Model 3/Y. It is recommended that you get an AGM battery, and it will definitely be more expensive than the OEM battery you can buy from a Service Center. Also, not all auto parts stores will have stock of a Group Size 51R AGM battery, but they will have non-AGM batteries and can usually get the AGM battery next day.
 
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You can buy a Group Size 51R battery at pretty much any auto parts store (and many big box stores). That's a direct replacement for the 12v battery in the Model 3/Y. It is recommended that you get an AGM battery, and it will definitely be more expensive than the OEM battery you can buy from a Service Center. Also, not all auto parts stores will have stock of a Group Size 51R AGM battery, but they will have non-AGM batteries and can usually get the AGM battery next day.
Appreciate the info- I think none of us have ever spend so much time ever worrying about a 12V car battery
 
This morning, the 12v was completely dead because the door wouldn't even open. But, I managed to jump start it :)

Does a 9v battery not open the frunk anymore? I heard a weak servo noise when connecting to battery terminals, but it sounded like it was too weak to pop the frunk. I had to use the 12v Li-Ion booster instead. And was able to drive the vehicle.
 
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Are you able to get Tesla to replace the 12V battery if it's not dead yet as more of a preventative maintenance type deal? I'm coming up on 25k miles which seems to be the giveaway point.

Not for free (under warranty), you cant.

You can certainly schedule tesla to come do it proactively for you (costs $129 total, parts and labor) or you can go buy the battery and do it yourself if you are a person who wants to do it yourself. The battery itself is $85.

I paid tesla to proactively replace mine, using mobile service in my driveway, while I was working from home. My car is 2.5 years old, and the $129 for "preventative service" did not bother me as a cost.

If you want it under warranty, you need to wait until you get a warning for it (or you dont get a warning for it, and end up with the car not being able to operate).
 
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Not for free (under warranty), you cant.

You can certainly schedule tesla to come do it proactively for you (costs $129 total, parts and labor) or you can go buy the battery and do it yourself if you are a person who wants to do it yourself. The battery itself is $85.

I paid tesla to proactively replace mine, using mobile service in my driveway, while I was working from home. My car is 2.5 years old, and the $129 for "preventative service" did not bother me as a cost.

If you want it under warranty, you need to wait until you get a warning for it (or you don't get a warning for it, and end up with the car not being able to operate).
I agree for the 12V battery, proactive preventative replacement may be the best option if one does not want to deal with unexpected situation of a dead car and you have to reach someplace on time- or worse you are on a vacation with family ( trust me family will remember it for a long long time).