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Model 3 12v battery dead
- Thread starter JTesmod3
- Start date
my 2018 model 3 12V battery appears to have died overnight - no warning prior. Texas. Just as hot as every other day this summer. My model 3 was completely unresponsive on Sunday morning. After following various procedures, I got the trunk opened and temporary power to the 12v terminals, which brought everything back to life. The main battery cell says I've got 100 miles of range. There were Several alerts about the 12v battery and the need to get to service.
My problem is that the 12v will not charge and when I remove the temporary power, the car dies again, so I cannot drive it to get serviced.
1) is there a replacement I can buy at a local car parts store (i.e so I can get it *today*?) 1B) What battery would that be?
2) If not self-serve option is available, I have to hire a flatbed towing service to get it to the nearest service center? I've contacted Tesla service advisors (now Tuesday morning) and waiting for a callback to confirm these logistics - I'm not sure I can just show up with a tow truck for a drop-off.
My problem is that the 12v will not charge and when I remove the temporary power, the car dies again, so I cannot drive it to get serviced.
1) is there a replacement I can buy at a local car parts store (i.e so I can get it *today*?) 1B) What battery would that be?
2) If not self-serve option is available, I have to hire a flatbed towing service to get it to the nearest service center? I've contacted Tesla service advisors (now Tuesday morning) and waiting for a callback to confirm these logistics - I'm not sure I can just show up with a tow truck for a drop-off.
FWIW just to follow up on this I bought a battery for $85 from Tesla even though I was still in warranty. Mine was coming up on 3 years old and just wanted to get it swapped for peace of mind. It's really a VERY easy swap and mostly just like a normal 12v swap after you shut the car down and disconnect the HV connector under passenger seat.
@mmw09 if you have an 18 tesla mobile will come replace it if you are still under warranty, or you can do like I did and go to a tesla service center and they will sell you a battery directly. Tesla will give you a big talk about not being responsible for anything you damage doing your own swap but really, if you just follow the below video it's very easy.
Only thing i'd add to this video if you are doing OEM is to make sure to disconnect the vent tube from old battery and reconnect on replacement.
@mmw09 if you have an 18 tesla mobile will come replace it if you are still under warranty, or you can do like I did and go to a tesla service center and they will sell you a battery directly. Tesla will give you a big talk about not being responsible for anything you damage doing your own swap but really, if you just follow the below video it's very easy.
Only thing i'd add to this video if you are doing OEM is to make sure to disconnect the vent tube from old battery and reconnect on replacement.
what are you using to temporarily power the 12v? Do you here the contactors close when you apply the 12v Power? if it’s a trickle charger, probably doesn’t have enough power to close the contactors. Once the contactors close you should be able to even disconnect a healthy 12v battery and drive the car. Maybe the power source isn’t strong enough to close the contactors….or something else is wrong other than the 12v battery.
iwannam3
Active Member
Exactly what I have done, proactively replace the battery, $85 in Oregon, no sales tax, and Tesla doesn't charge a core charge. Hopefully the updated charging software will extend the life now. And possibly a retro fit kit for the new S Li 12 volt battery and BMS. Ohmuu is about 5 X the Tesla battery. And who knows how long Tesla will allow a non spec battery play with their software? Ohmu had to redo their BMS when Tesla made a change and they started throwing weird error codes. When improving the charging for the OEM lead acid, why would Tesla spend time and money making sure someone's LI battery swap works?
iwannam3
Active Member
If you check NAPA and several others they don't list a battery. NAPA shows a tire pressure monitor! Just get one from Tesla. $85. It is NOT an AGM, especially at that price, it has a vent and tubing on the driver's side. Not sealed.
Assuming that the only thing wrong with your car is the 12v battery, you can put off getting it replaced as long as you keep your main battery charged and the vehicle awake.
The 12v battery is only used when the car is asleep and also to wake it up.
Once the car is awake, the 12v system is powered by the main battery pack through the DC/DC converter.
There are various ways to keep the car from sleeping. I’m feeling lazy today, and don’t want to type them all out again, especially since I’m posting from my phone. But if you look around a bit, you’ll find a bunch of ways to keep your car awake. Those same threads also have a lot of nice to know info on the 12v system.
The 12v battery is only used when the car is asleep and also to wake it up.
Once the car is awake, the 12v system is powered by the main battery pack through the DC/DC converter.
There are various ways to keep the car from sleeping. I’m feeling lazy today, and don’t want to type them all out again, especially since I’m posting from my phone. But if you look around a bit, you’ll find a bunch of ways to keep your car awake. Those same threads also have a lot of nice to know info on the 12v system.
iwannam3
Active Member
If the battery is failing with an open, short, high amp load or high resistance the DC/DC converter can see the fault and stop charging into a failing battery to protect the DC/DC converter. It isn't like an alternator supplying power with a dead battery. The alternator is stupid and will boil the battery but usually you can keep running. You don't want to fry the DC/DC converter, it is inside the main battery pack.
THX for good info! I ended up taking the old battery to the Tesla dealership and swapping it for a new one for $85. They advised that if I had simply used roadside assistance that they would have sent someone over to assess and replace (or two the car if needed). I assumed roadside assist was for towing only since it uses the vocabulary "pickup location" as part of the process. They should change that to "support location." They apparently triage the request and decide course of action. Good to know. Unfortunate that it happened out of the blue and on a holiday weekend, but glad the car was at home when it died. Summary: Despite a frustrating three days; I now now a lot more about how that car works and what I'll do next time! Great forum posts and info here!
If you have an '18 that is coming up on 3 years of warranty, but haven't received any 12V battery warning (and it hasn't died), Tesla will not preemptively replace it for free, correct? But you can schedule a mobile service appointment and pay $85 for the battery, plus labor, for them to come swap it out? Anyone know how much the labor charge is?
I just really don't want to find my battery unexpectedly dead some day.
I just really don't want to find my battery unexpectedly dead some day.
I want to say it was $129ish for them to replace it. That might have been in the service center though.
Yup, exactly. I let my laziness get the best of me… I should’ve mentioned that you really need to hook up a battery tester (most new “smart” battery chargers have testing functionality) before doing what I suggested in that post.
surfrasch
Member
My 3 will be 3 years old in November. I’ve got a 14 hr drive coming up in Oct, so decided to swap the 12V beforehand in two weeks. Mobile service quoted me$119.56.
glad you got it fixed. Can you comment on my questions above regarding what you used to try and jump the car with? Did hear the contactors close before removing the 12v power source you applied? Would help those of us that have jump packs in the frunk and plan to jump the car if/when the 12v fails.
FWIW my battery was so dead I couldn't get the contactors to close at all. Main reason I went ahead and manually swapped my 2nd car just to have it done and not worry about it.
what were you using to try and jump it? I’ve also read a post or two that when they couldn’t get the contactors to close, they were successful after totally disconnecting the failed 12v battery. Maybe it has to do with the sulfur smell, indicating an internal failure, causing a lot of resistance, and/or the car sensing it and not allowing the contactors to close? Did you try completely disconnecting the 12v when jumping it?
Just wondering If my hulkman jumper that can easily start a v6 Infiniti by itself(tested)….why it wouldn’t be able to close the contactors on a Tesla?
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