Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

12 Volt battery died yesterday

This site may earn commission on affiliate links.
Out of the blue, no warning, I get a whole bunch of errors and then it tells me the 12volt needs to be replaced. It wouldn't even move and luckily I had another car to pick up my daughter from school. When I got back, I plugged in the charger and it rebooted the touch screen. I was able to drive it this morning to get the battery replaced.

Car was at like 85% so its not like I let the main battery run down. It was extremely frustrating to have to redo each and every setting. The car has less than 15000 miles and 15 months old. I'm guessing every 15 months I'm going to be redoing every single setting? I can't understand how a car with 2 batteries can manage to lose every single setting including the name of the car, yet it could manage to keep the car keys loaded in memory. I almost had an accident as I didn't know how to use the wipers, they are always on auto which the car decided to turn off.

According to Tesla, the battery should be covered for the 4 year warranty, but I'm still pretty ticked that there apparently is a major design flaw to lose every setting especially when the battery wasn't even removed.

What kind of bothers me even more than that though is that my options were drive in this morning, not last night because the computers apparently were down and they couldn't guarantee apparently that they could change a warranty battery without the computers being up. I can't use my car because their computers are down?? Seriously? The other option was mobile service could come Monday. Since I've owned this car, mobile service is always after going into the place so that is a bit frustrating. Last and the most ridiculous of all was I talked to roadside and they said they could tow me into the service center. AAA can change a car battery, but Tesla roadside cannot? Towing the car in I'm sure is a lot cheaper, not to mention the potential damage that can happen.
 
upload_2020-10-31_20-33-35.jpeg
 
  • Like
Reactions: GlmnAlyAirCar
When's the last time you got a flat tire? Batteries don't die in 15 months and of they do, you have a solid way to take care of it.

Holy Drama.
How can a car battery failure (which is a known issue) be such a dramatic life crisis, with so many, “And that’s not the worst part” moments. :)

I sure don’t want to be around when you get a flat tire, or a turn signal burns out.
That will most definitely be a life changing crisis.
 
When's the last time you got a flat tire? Batteries don't die in 15 months and of they do, you have a solid way to take care of it.

lol. I think this has been established. It’s a battery issue.
Just wondering why all the life altering drama is needed for the big battery incident.
Sounds like you’re having a life crisis over this battery.
If you need a support line to get through this let me know.
I’ll see if I can dig up a crisis management line for you.
 
@robl45 I imagine that using one of those portable jumpstart battery would provide a little bit of juice to your car,
and sufficient enough to perform some diagnostic, in particular to check the voltage of your battery.

If the voltage is around 12 to 12.5 V, the inboard charger is not charging.
If the voltage is around 14 to 14.5 V, the inboard charger charging the 12 V battery.

I installed a Bluetooth 12 V Battery Monitor so I can check when the 12 V battery get recharged
with the internal DC/DC converter even when the car is locked, using Bluetooth and my phone APP.

When I am not using my car, and keep the car locked for few days,
I noticed that the 12 V battery get recharged with the DC/DC converter during about 2 hours, about every 36 hours .

I have a two year old battery, I live in Northern California, and I park at night in a garage.
You can see that the battery lost (13.18 - 12.62) = 0.56 V in 36 hours while sleeping, or about 15 mV an hour.

M3 12V .jpg


@robl45 in the case of your used battery, I suspect that the DC/DC converter tried to charge your battery but noticed that
after stopping charging the battery, the voltage was going down very fast as the battery was not able to keep the charge.

So the DC/DC converter (may be) decided not to continue charging the 12 V battery to avoid dumping too much energy
from the high voltage propulsion battery.

I'm surprised that Tesla didn't send an early warning to inform about the 12 V battery charging issue?

It is a pity that Tesla doesn't display the 12 V voltage of the battery on the central display,
and don't give a battery status information for the 12 V battery by checking the discharge rate.

It is strange that Tesla can calculate with great precision the energy needed to reach a Supercharger without been stranded,
but cannot send a warning diagnostic of the 12 V battery degradation to avoid the kind of bad experienced the OP encountered.

Note: I would strongly recommend to anyone, as first accessory, to get one of those digital voltmeters connected to the Auxiliary plug,
so this would allow to check if the battery get charged, which happen every time you unlock your car, or access remotely your car,
and check the default battery voltage when the battery is not charged by the DC/DC converter.
 
Last edited:
One update failed 3 times, I'm wondering if that was maybe a sign the battery was going dead?

I didn't notice yesterday, but recently I noticed loud fans going while the car was in the garage. I assume that was cooling the battery or something but maybe that helped kill it too? Still I've owned over 20 vehicles and never had one die this quick and any time one has died was because I hadn't driven much and it went flat. Usually would take a couple of times at that to kill it
 
Out of the blue, no warning, I get a whole bunch of errors and then it tells me the 12volt needs to be replaced. It wouldn't even move and luckily I had another car to pick up my daughter from school. When I got back, I plugged in the charger and it rebooted the touch screen. I was able to drive it this morning to get the battery replaced.

Car was at like 85% so its not like I let the main battery run down. It was extremely frustrating to have to redo each and every setting. The car has less than 15000 miles and 15 months old. I'm guessing every 15 months I'm going to be redoing every single setting? I can't understand how a car with 2 batteries can manage to lose every single setting including the name of the car, yet it could manage to keep the car keys loaded in memory. I almost had an accident as I didn't know how to use the wipers, they are always on auto which the car decided to turn off.

According to Tesla, the battery should be covered for the 4 year warranty, but I'm still pretty ticked that there apparently is a major design flaw to lose every setting especially when the battery wasn't even removed.

What kind of bothers me even more than that though is that my options were drive in this morning, not last night because the computers apparently were down and they couldn't guarantee apparently that they could change a warranty battery without the computers being up. I can't use my car because their computers are down?? Seriously? The other option was mobile service could come Monday. Since I've owned this car, mobile service is always after going into the place so that is a bit frustrating. Last and the most ridiculous of all was I talked to roadside and they said they could tow me into the service center. AAA can change a car battery, but Tesla roadside cannot? Towing the car in I'm sure is a lot cheaper, not to mention the potential damage that can happen.


What happened on the October 27th appointment you were supposed to have because your OTA updates were not applying?
 
You would think it would be easy enough to detect the 12volt is failing, but I don't even understand why this is happening at all.
24 months seems to be the average for a battery that is constantly getting tendered.

Am I understanding this correctly? I can expect my TM3’s 12 volt battery to need replacement every 24 months?

During 10 years’ of ownership, I replaced the 12 volt in my 2004 Prius once, and that was only because the dealership said it was “overdue”.

I had a 2003 Mazda B4000 until 2011 and replaced the battery once.

I have a 2009 B4000 with the original battery and a 2014 Prius v with the original battery.
 
No, 24 months is if you get lucky :)

Am I understanding this correctly? I can expect my TM3’s 12 volt battery to need replacement every 24 months?

During 10 years’ of ownership, I replaced the 12 volt in my 2004 Prius once, and that was only because the dealership said it was “overdue”.

I had a 2003 Mazda B4000 until 2011 and replaced the battery once.

I have a 2009 B4000 with the original battery and a 2014 Prius v with the original battery.