-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
12 Volt battery died yesterday
- Thread starter robl45
- Start date
I would very much like to know if a jumpstart battery would work. It takes little room and could be a life saver.
copyhacker
Member
My 12V died 2 nights ago in my garage (2018 Model 3, 33K miles, had it exactly 2 years today). I didn’t get any warnings ahead of time. Luckily, I was home at the time. We were going to take it on a road trip this weekend, so I’m glad it decided to fail first. Mobile service scheduled for Tuesday. The worst thing about it has been having to endure my wife saying “I thought this car was perfect?”.
Curiously, like the OP, i did have a couple of software updates fail a few times before going through.
No one told me losing a 12V would stink this much (literally, my garage reeks of sulfur).
Curiously, like the OP, i did have a couple of software updates fail a few times before going through.
No one told me losing a 12V would stink this much (literally, my garage reeks of sulfur).
You are lucky you can wait till Tuesday. My wife is skeptical so anything especially a battery dying and killing the car is not making her take one. She is the typical consumer and this is what people are worried about, not self driving.
Last edited:
Not sure about the little ones, but I was able to use a larger traditional jump start battery to get my 3 going when it died. Downside is you depending on how much notice you get, you might have to pop the frunk using the two leads under the tow cover. In that case, you are locked out of the rest of the car and may not be able to retrieve a jump starter. (Without 12V power the doors won’t open).
copyhacker
Member
I just told her that 1) I could change it myself and not have to wait, but that would mean paying out of pocket vs waiting for warranty service; and 2) I’ve had to replace a dead 12V in the ICE SUV at least twice, so nothing to see here. 
I just told her that 1) I could change it myself and not have to wait, but that would mean paying out of pocket vs waiting for warranty service; and 2) I’ve had to replace a dead 12V in the ICE SUV at least twice, so nothing to see here.
Even my wife knows number 2 is nonsense. Batteries don't go that quick nor prevent functions from working. Was hoping to get her a Tesla, looks like that not happening.
EnrgyNDpndnce
Member
If you are suggesting that in the history of ICE vehicles there have never been any premature failures of 12V batteries, even in less than two years, well I think it’s safe to say you are mistaken. And yes in ICE cars when the battery dies things do indeed stop working. Sorry this happened to you but it’s a minor inconvenience and Tesla is not the first, nor will it be the last, manufacturer to have some batteries fail prematurely. Get it replaced under warranty and move on.
As the other poster said, it's not normal to die in two years or less, and I personally In 30 years have never had a battery die without being drained down. Further, you start an ice and the alternator runs everything, you don't lose half the functions because the battery needs to be replaced.
I was worried about my 12v going out prematurely during an upcoming road trip. I proactively scheduled a mobile service appointment to have the 12v changed out of warranty since it technically didn’t fail (yet). They came the next day and swapped it out for $120. It was worth the peace of mind and should be good for another two years. I understand it should last for 4 years, but it’s not worth all the stress. April 2018 RWD with 25,000 miles.
And that was precisely what I brought up in the first post. If you on a road trip and it dies, you could be screwed. In an ice vehicle, they come and swap the battery, Tesla should be able to do that.
EnrgyNDpndnce
Member
And as I’ve said in other 12V threads, it is quite easy to swap the Model 3 12V yourself. I bought one at O’Reilly after mine died at 80k miles. In my case I did get the 12V warning roughly 24 hours before it died. So no you’re not screwed if your battery dies. These chicken little threads are getting old.
Hmmmm... so my almost 3 yr old almost 30k mile M3 could do with a proactive swap to a new 12v ? (just in case). Seems like a no brainer.
Is it fairly straight forward (disconnect terminals - take out old - put in new - connect terminals) ? Or is there a requirement that an electronic engineer be on hand to resuscitate an inevitable software failure?
I was greatly concerned with our 12v battery failure. They towed it, replaced it, and had it back by noon the next day.
Now I’m not afraid of it. It jumped easy with the lithium pack. It’s in an easy location. I’ll probably pickup a new battery from Tesla around 18 months in.
I do think they might have a charging problem, cooking the battery around updates. Have a battery monitor on it so I’ll know next time.
I think they were trying to get more aggressive about identifying battery failure, but the ended up detecting the ohmu battery falsely due to its different charge profile. So back to the drawing board.
Now I’m not afraid of it. It jumped easy with the lithium pack. It’s in an easy location. I’ll probably pickup a new battery from Tesla around 18 months in.
I do think they might have a charging problem, cooking the battery around updates. Have a battery monitor on it so I’ll know next time.
I think they were trying to get more aggressive about identifying battery failure, but the ended up detecting the ohmu battery falsely due to its different charge profile. So back to the drawing board.
MarsOrBust
Member
My understanding you just don’t swap this 12 volt battery like an ICE car. The high voltage harness needs to be unplugged first. I can see somebody deciding to change it like on an ICE car and get in worst trouble.
EnrgyNDpndnce
Member
All we know is a relatively small number of Model 3 batteries (couple dozen on TMC relative to the 500k+ having been sold) have experienced premature failures. To date I haven’t seen any hard data on the failure rate vs the typical early failure rate in other cars, so I can’t intelligently comment on whether Tesla has a problem. If it were me, I’d keep driving until there’s a problem. However, if you think it’s worth spending $150 - $200 to proactively replace the battery then I can’t call that a bad decision as it’s your money.
FWIW the replacement is fairly straightforward. There are any number of videos walking you thru the process, I viewed one by @MTN Ranger before swapping mine out. I am capable of basic DIY projects but am certainly no DIY expert and I had no problem swapping the battery myself. There are those who say you must disconnect the high voltage pack first but I haven’t seen anything official on that. I did not and am still alive, so either you don’t have to or I got lucky. I paid $200 for a 51R AGM battery and plopped it in myself on a Sunday afternoon. Didn’t want to wait for Tesla ranger service to come Monday or Tuesday since my battery was dead so I did it myself. However, if you’re going to do the proactive swap (meaning your battery is not dead) you might want to use Tesla Ranger service for that. I have read that folks have paid them $150 to replace the battery so if it were me I’d save the $50 and let them come to you.
It's other forums too. It is an issue, Tesla support was quite aware of the issue when I called.
EnrgyNDpndnce
Member
I’ve read this same comment several times but have yet to find anything official from Tesla saying you must disconnect the HV pack before swapping out the 12V. Do you have something from Tesla and if so would you mind sharing that information here? As I said in my previous post, I did not disconnect the HV pack and I’m still alive, so either you don’t have to or I got lucky. I would like to know what Tesla says about this because I take safety seriously and if there is guidance to disconnect the HV pack I will certainly follow it next time.
EnrgyNDpndnce
Member
It’s an issue if one 12V fails prematurely, especially for the owner of that car. What I’m saying is we don’t have the data to determine if it’s a statistically significant issue. Saying “Tesla knows about it” or “it’s on other forums too” is anecdotal, not hard data. If you have any hard data please share it here. As I have said in the several other 12V threads, if the data shows there’s a really significant issue I’m happy to criticize Tesla for it. But to date all we have are a small number of complaints and no hard data. And we have a few people comparing a dead 12V battery to an end of life event.
Do you work for an auto company? Its thinking like this that caused Weinstein to get away with the things he did. No hard data. Bumpers falling off cars is just a few so there is no hard evidence that its a problem right? Seriously? There is plenty of threads all over the internet and its not just model 3, its all the models and its been going on for years.
