12v question

[Jkimo11]

Is the 12v user replaceable in the sense that if I do it the warranty isn't voided?

 

[Supcom]

Is the 12v user replaceable in the sense that if I do it the warranty isn't voided?

Yes. It's like a traditional car battery, just much smaller.

 

[Jkimo11]

Thanks.... can you jump it or charge it if the voltage gets low? I have a NOCO Lithium jump battery that I use on my current ICE vehicle.
Just trying to figure out how to fix things myself before a purchase as I'm very far from a service center.

 

[brkaus]

Yes. It can be jumped. Read your manual for info on how to access.

There is a cable that is supposed to be disconnected when changing the battery - at least in my 2018 model 3. But otherwise easy.

I assume you have one of the models with a lead acid battery?

Does mobile service hit your area? Just had my 3 battery replaced for $114. In our office parking lot.

 

[dude7]

I woke up yesterday (Sunday) to a dead 12v battery in my 2020 MYLR. I drove it the night before and no 12v warning or anything. I even charged the car overnight to 80%.

In the morning, my wife couldn't get into the car. The only door that would initially open was the rear passenger, which was ripped open without the window even partially going down. Then somehow the driver door opened with the window coming down like it normally does, but then the window would not go up again and the door would not unlatch with the button. (The emergency release obviously still worked.) The frunk also would not open, so I had to go through the emergency procedure for opening the frunk to access the 12v battery.

I tried "jumpstarting" with our ICE car and it didn't work. I found an old 12v car battery charger and hooked that up for 30 minutes until the charger said the battery was full and it did not work. I COULD NOT DRIVE THE CAR. Because my car was on the driveway and rain was coming, I had to tape up the driver side window. In fact, nothing on the left side of the car was working (not windows, not door latches, not the mirror, not the charge port door). The right side of the car still worked for some stupid reason (windows, latches, mirror). I scheduled Tesla mobile service and they were able to get me an appointment for 8:00 a.m. today (Monday).

So, when my 12v battery died WITHOUT WARNING, the entire left side of the car wouldn't work and could not drive. I know you can go buy a 12v battery from the Tesla Service Center, but if your 12v battery dies when they are closed, YOU ABSOLUTELY CAN GET STRANDED. I thought about buying a smaller battery from a car parts store for over $200 -- and it wouldn't even be an exact fit -- but decided to suck it up for a day and just hope my taped up window wouldn't let water in during the rain.

The mobile service tech was able to replace my battery in less than 5 minutes this morning and everything worked again. I mentioned to him that the 12v died without warning for me and he said that he sees it and wished that it would give warnings, implying that my situation was at least not rare.

Moral of the story: replace that 12v battery as soon as you get a warning. You can buy it from the service center or have a mobile tech replace it for you.

 

[Supcom]

I woke up yesterday (Sunday) to a dead 12v battery in my 2020 MYLR. I drove it the night before and no 12v warning or anything. I even charged the car overnight to 80%.

In the morning, my wife couldn't get into the car. The only door that would initially open was the rear passenger, which was ripped open without the window even partially going down. Then somehow the driver door opened with the window coming down like it normally does, but then the window would not go up again and the door would not unlatch with the button. (The emergency release obviously still worked.) The frunk also would not open, so I had to go through the emergency procedure for opening the frunk to access the 12v battery.

I tried "jumpstarting" with our ICE car and it didn't work. I found an old 12v car battery charger and hooked that up for 30 minutes until the charger said the battery was full and it did not work. I COULD NOT DRIVE THE CAR. Because my car was on the driveway and rain was coming, I had to tape up the driver side window. In fact, nothing on the left side of the car was working (not windows, not door latches, not the mirror, not the charge port door). The right side of the car still worked for some stupid reason (windows, latches, mirror). I scheduled Tesla mobile service and they were able to get me an appointment for 8:00 a.m. today (Monday).

So, when my 12v battery died WITHOUT WARNING, the entire left side of the car wouldn't work and could not drive. I know you can go buy a 12v battery from the Tesla Service Center, but if your 12v battery dies when they are closed, YOU ABSOLUTELY CAN GET STRANDED. I thought about buying a smaller battery from a car parts store for over $200 -- and it wouldn't even be an exact fit -- but decided to suck it up for a day and just hope my taped up window wouldn't let water in during the rain.

The mobile service tech was able to replace my battery in less than 5 minutes this morning and everything worked again. I mentioned to him that the 12v died without warning for me and he said that he sees it and wished that it would give warnings, implying that my situation was at least not rare.

Moral of the story: replace that 12v battery as soon as you get a warning. You can buy it from the service center or have a mobile tech replace it for you.

12V lead acid batteries in ICE cars often fail with little warning so it's no surprise that the Tesla battery can do the same. As far as being stranded goes, as you contemplated, if you could find a small non-Tesla battery at a late night auto parts store, you might be able to avoid being stranded very long.

And, there are plenty of other ways you could be stranded with no warning. A tire blowout is the easiest and most likely. I've had three of them in the last two years! I haven't had a 12V battery failure, but it may be time to proactively replace mine.

 

[dude7]

12V lead acid batteries in ICE cars often fail with little warning so it's no surprise that the Tesla battery can do the same. As far as being stranded goes, as you contemplated, if you could find a small non-Tesla battery at a late night auto parts store, you might be able to avoid being stranded very long.

And, there are plenty of other ways you could be stranded with no warning. A tire blowout is the easiest and most likely. I've had three of them in the last two years! I haven't had a 12V battery failure, but it may be time to proactively replace mine.

Some more thoughts: You're absolutely right that no car in my lifetime has ever warned me or my family about a failure before it fails -- they just simply fail. However, I think we've been able to jumpstart every single one to get to our next destination. I'm just frustrated that I wasn't able to do that with the battery in my Model Y. Even after charging the 12v battery to full with a car battery charger, the Tesla software didn't reset. If the car started, I could have at least driven it into my garage, out of a rainstorm that made national news, and tinkered some more.

I got pretty soaked doing all of this in the rain. I didn't try shutting down the car, but I was afraid that the right side of my car would also stop functioning. Again, the rainstorm factored into me being more risk-adverse than usual. I would also have tried to disconnect the battery to see if it would read the voltage and reset the low voltage error and other errors. However, this happened on my driveway and I got lucky. If I were away from my house, I'd guess that a good number of people carry around jumper cables, but I found out that wouldn't fix anything with the Model Y. I don't know as many people who would have at least one tool in their cars available to disconnect the battery. If this happened away from my house, that would be a much bigger problem in a rainstorm.

The point is, you can get stranded because you can't just jumpstart the battery in an emergency.

 

[hpartsch]

I woke up yesterday (Sunday) to a dead 12v battery in my 2020 MYLR. I drove it the night before and no 12v warning or anything. I even charged the car overnight to 80%.

In the morning, my wife couldn't get into the car. The only door that would initially open was the rear passenger, which was ripped open without the window even partially going down. Then somehow the driver door opened with the window coming down like it normally does, but then the window would not go up again and the door would not unlatch with the button. (The emergency release obviously still worked.) The frunk also would not open, so I had to go through the emergency procedure for opening the frunk to access the 12v battery.

I tried "jumpstarting" with our ICE car and it didn't work. I found an old 12v car battery charger and hooked that up for 30 minutes until the charger said the battery was full and it did not work. I COULD NOT DRIVE THE CAR. Because my car was on the driveway and rain was coming, I had to tape up the driver side window. In fact, nothing on the left side of the car was working (not windows, not door latches, not the mirror, not the charge port door). The right side of the car still worked for some stupid reason (windows, latches, mirror). I scheduled Tesla mobile service and they were able to get me an appointment for 8:00 a.m. today (Monday).

So, when my 12v battery died WITHOUT WARNING, the entire left side of the car wouldn't work and could not drive. I know you can go buy a 12v battery from the Tesla Service Center, but if your 12v battery dies when they are closed, YOU ABSOLUTELY CAN GET STRANDED. I thought about buying a smaller battery from a car parts store for over $200 -- and it wouldn't even be an exact fit -- but decided to suck it up for a day and just hope my taped up window wouldn't let water in during the rain.

The mobile service tech was able to replace my battery in less than 5 minutes this morning and everything worked again. I mentioned to him that the 12v died without warning for me and he said that he sees it and wished that it would give warnings, implying that my situation was at least not rare.

Moral of the story: replace that 12v battery as soon as you get a warning. You can buy it from the service center or have a mobile tech replace it for you.

Curious how many miles are on your car? Is it a late or early 2020?

 

[gottagofast]

Jumping in to ask another question related to this, will a A23 battery really pop the frunk if your 12v dies? How long is the a23 good for before it can’t pop the frunk anymore

 

[gottagofast]

I woke up yesterday (Sunday) to a dead 12v battery in my 2020 MYLR. I drove it the night before and no 12v warning or anything. I even charged the car overnight to 80%.

In the morning, my wife couldn't get into the car. The only door that would initially open was the rear passenger, which was ripped open without the window even partially going down. Then somehow the driver door opened with the window coming down like it normally does, but then the window would not go up again and the door would not unlatch with the button. (The emergency release obviously still worked.) The frunk also would not open, so I had to go through the emergency procedure for opening the frunk to access the 12v battery.

I tried "jumpstarting" with our ICE car and it didn't work. I found an old 12v car battery charger and hooked that up for 30 minutes until the charger said the battery was full and it did not work. I COULD NOT DRIVE THE CAR. Because my car was on the driveway and rain was coming, I had to tape up the driver side window. In fact, nothing on the left side of the car was working (not windows, not door latches, not the mirror, not the charge port door). The right side of the car still worked for some stupid reason (windows, latches, mirror). I scheduled Tesla mobile service and they were able to get me an appointment for 8:00 a.m. today (Monday).

So, when my 12v battery died WITHOUT WARNING, the entire left side of the car wouldn't work and could not drive. I know you can go buy a 12v battery from the Tesla Service Center, but if your 12v battery dies when they are closed, YOU ABSOLUTELY CAN GET STRANDED. I thought about buying a smaller battery from a car parts store for over $200 -- and it wouldn't even be an exact fit -- but decided to suck it up for a day and just hope my taped up window wouldn't let water in during the rain.

The mobile service tech was able to replace my battery in less than 5 minutes this morning and everything worked again. I mentioned to him that the 12v died without warning for me and he said that he sees it and wished that it would give warnings, implying that my situation was at least not rare.

Moral of the story: replace that 12v battery as soon as you get a warning. You can buy it from the service center or have a mobile tech replace it for you.

So in the end was it just a 12v battery that you couldn’t jump? It started working again after you replaced the battery?

 

[dude7]

Sorry, I'm not very active here. I took screenshots of all the error codes when I got them. I really don't understand why the 12v battery is so essential when the main battery can work as a backup. You can see in all of these pictures that my main battery was at 79%.

It's stupid how much can go wrong when the 12v battery dies. @gottagofast, yes everything worked again after the 12v battery was replaced.

 

[dude7]

Jumping in to ask another question related to this, will a A23 battery really pop the frunk if your 12v dies? How long is the a23 good for before it can’t pop the frunk anymore

Any 12v battery or 12v DC source will work. I used my 12v battery charger to open the frunk. Both Energizer and Duracell say the shelf life is 5 years for their A23 batteries.

 

[brkaus]

Most of the time the 12v can be overpowered by the main battery. But some failures like a dead short in a cell are still problematic.

 

[Supcom]

Jumping in to ask another question related to this, will a A23 battery really pop the frunk if your 12v dies? How long is the a23 good for before it can’t pop the frunk anymore

An A23 battery will open the frunk IF the low voltage battery is dead OR the car is already unlocked. A 9V battery will likely also work (easier to get if you are stranded someplace) but is a little harder to fit behind the bumper plug.

I would replace the A23 every year. They're cheap.

 

[father_of_6]

From what I've read, the original roadster didn't have a 12v battery. The problem with that was that 12v accessories could drain the main battery and leave you stranded.

I believe the 12v battery is required to open the contactors so that the HV battery can engage. The tow hook trick for opening the frunk is just so you can get into the frunk to replace the dead 12v.

 

[Supcom]

I really don't understand why the 12v battery is so essential when the main battery can work as a backup.

The low voltage battery (12V or 16V) provides the current used to close the main battery contactor. So long as the contactor is closed, the main battery will (usually) provide the power through the low voltage converter to keep the low voltage system powered and keep the contactor closed. But, if the car goes into sleep mode, the contactor is opened and the HV battery is disconnected. Now, if the low voltage battery is dead, there is no power available to close the contactor, and the main battery cannot supply power to anything.

So, you need a 12V jump box to power the computers and such long enough to close the contactor. And, since the car is dead, to get access to the jump terminals, you need a 9-12V battery to open the frunk.

 

[gottagofast]

I thought even if your 12v battery was bad that a jump would atleast be enough to put the car into drive so could get to your destination, if the jumper is putting power through the bad battery why wouldn’t it let you open your doors and put it into drive in some cases

 

[gottagofast]

I thought even if your 12v battery was bad that a jump would atleast be enough to put the car into drive so could get to your destination, if the jumper is putting power through the bad battery why wouldn’t it let you open your doors and put it into drive in some cases

I wonder if the new 16v lithium will have this same problem when they start dying? Will a jumper be able to put it into drive

 

[Supcom]

I thought even if your 12v battery was bad that a jump would atleast be enough to put the car into drive so could get to your destination, if the jumper is putting power through the bad battery why wouldn’t it let you open your doors and put it into drive in some cases

A jump box will power up the computers and accessories and let you open the doors and start the car. Once that is done, you should be able to drive. If the battery is shorted out too badly, this might not work until you get a new battery. But usually, like an ICE car, a jump start will be sufficient to let you drive.

The issue is that in order to connect the jump box, you need to open the frunk. That requires a 9-12 volt battery (a jump box will also work). But, if your jump box is in the frunk you need a small battery to unlatch the frunk.

The 16V system is similar. Although the lithium battery should be very reliable, if it does die, you can use a 12V jump box. There is a terminal for the 12V to connect to.

Look up jumpp start a tesla on you tube and you should find plenty of videos showing how to do this.

 

[gottagofast]

A jump box will power up the computers and accessories and let you open the doors and start the car. Once that is done, you should be able to drive. If the battery is shorted out too badly, this might not work until you get a new battery. But usually, like an ICE car, a jump start will be sufficient to let you drive.

The issue is that in order to connect the jump box, you need to open the frunk. That requires a 9-12 volt battery (a jump box will also work). But, if your jump box is in the frunk you need a small battery to unlatch the frunk.

The 16V system is similar. Although the lithium battery should be very reliable, if it does die, you can use a 12V jump box. There is a terminal for the 12V to connect to.

Look up jumpp start a tesla on you tube and you should find plenty of videos showing how to do this.

Yea it should work but I was reading what someone else in here said, and that was that the car wouldn’t open or go into drive even when jump starting

Hopefully this is near impossible to happen with the 16v lithium when it eventually dies