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"Proactive" 12v battery replacement - good idea or overkill?

I just had my 12V replaced under warranty. It was almost 4yrs old before I received the warning. For those of you waiting to replace your 12V until the last minute, keep in mind that the service center may not have any in stock. I had to wait 2wks for them to get new stock. I even had them check with another service center 200mi away in Stl and supposedly they were out of stock as well. The service center told me I'd be fine to drive for the 2wks, but there was no way I was taking that chance and getting stranded.
 
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I just had my 12V replaced under warranty. It was almost 4yrs old before I received the warning. For those of you waiting to replace your 12V until the last minute, keep in mind that the service center may not have any in stock. I had to wait 2wks for them to get new stock. I even had them check with another service center 200mi away in Stl and supposedly they were out of stock as well. The service center told me I'd be fine to drive for the 2wks, but there was no way I was taking that chance and getting stranded.
How long did they say it would last?
 

RayK

Safety Score 90 (Was 96!)
Apr 5, 2016
3,147
3,285
San Jose, CA
How long did they say it would last?
Well, assuming that the replacement battery is identical to the one that was installed when the car was new, it will probably last the same amount of time (all other things being equal). However, reading the "fine print" of the invoice when I had mine proactively replaced back in June (3 years, 11 months old), replacement parts are guaranteed for one year.

Quote:
"Tesla-branded parts purchased directly from Tesla over-the-counter, online or purchased and installed by Tesla Service are covered
under the Tesla Parts, Body, and Paint Repair Limited Warranty for a period of 12 months subject to the applicable terms, conditions
and exclusions and available at Customer and Product Support | Tesla Support"


UK terms may be different; consult the fine print of the invoice.
 
I just had my 12V replaced under warranty. It was almost 4yrs old before I received the warning. For those of you waiting to replace your 12V until the last minute, keep in mind that the service center may not have any in stock. I had to wait 2wks for them to get new stock. I even had them check with another service center 200mi away in Stl and supposedly they were out of stock as well. The service center told me I'd be fine to drive for the 2wks, but there was no way I was taking that chance and getting stranded.
Alternatively, you can buy a replacement lead acid battery almost anywhere that sells car batteries, but you need to find it by the group size. It's a group size 51R. It's easy to poop open the frunk and replace it yourself.
 
Well, assuming that the replacement battery is identical to the one that was installed when the car was new, it will probably last the same amount of time (all other things being equal). However, reading the "fine print" of the invoice when I had mine proactively replaced back in June (3 years, 11 months old), replacement parts are guaranteed for one year.

Quote:
"Tesla-branded parts purchased directly from Tesla over-the-counter, online or purchased and installed by Tesla Service are covered
under the Tesla Parts, Body, and Paint Repair Limited Warranty for a period of 12 months subject to the applicable terms, conditions
and exclusions and available at Customer and Product Support | Tesla Support"


UK terms may be different; consult the fine print of the invoice.
Oh sorry, I meant when the warning sign cones up did they say how long it would last if you can't get a battery straight away?
 

RayK

Safety Score 90 (Was 96!)
Apr 5, 2016
3,147
3,285
San Jose, CA
Oh sorry, I meant when the warning sign cones up did they say how long it would last if you can't get a battery straight away?
I believe that was answered in the post you quoted:

I just had my 12V replaced under warranty. It was almost 4yrs old before I received the warning. For those of you waiting to replace your 12V until the last minute, keep in mind that the service center may not have any in stock. I had to wait 2wks for them to get new stock. I even had them check with another service center 200mi away in Stl and supposedly they were out of stock as well. The service center told me I'd be fine to drive for the 2wks, but there was no way I was taking that chance and getting stranded.
I'm not sure I'd go with the opinion of a random tech at a random Tesla service center, unless they can provide some sort of hard data to back up that claim. There's so much variation in how the batteries are flagged as dying; I believe that some people here have stated that they were able to run several weeks with the warning message, others reported that the 12V battery died without any warning. It is a bit more hassle to deal with a dead 12V in a Tesla than it is for a "normal" ICE vehicle - applying power to the leads behind the tow cover in the front bumper to open the frunk, disconnecting the main battery using the connector under the right rear passenger seat. For peace of mind, it was worth it to me to swap out the 12V battery one month shy of the 4 year warranty expiring.
 

Durzel

Well-Known Member
Jul 17, 2019
5,397
4,581
Bath, UK
I’ve just had this warning pop up in my M3P, just under 2 3/4 years after I bought it.

I went into the app and booked immediately, but the earliest mobile appointment I could get is 4 days away. I have a trip on Tuesday planned but apart from that it’ll be sat on my drive.

I have an aftermarket (EVOffer) automatic frunk and trunk systems fitted, with the frunk one being directly attached to the 12v battery. I presume there is some vampire drain from them, is it possible my 12v failed prematurely because of it?

I don’t know if it’s noteworthy but prior to last week my car used to wake up every 2-3 days to top up the 12v, but in the last week it hadn’t. I even woke it up after 4 days because I was getting worried, but it went back to sleep again. It’s been a good 7 days since it last did a maintenance cycle so I presume that’s why it’s now complaining..

Also between now and then should I leave my frunk unlatched or any other tips?
 
I’ve just had this warning pop up in my M3P, just under 2 3/4 years after I bought it.

I went into the app and booked immediately, but the earliest mobile appointment I could get is 4 days away. I have a trip on Tuesday planned but apart from that it’ll be sat on my drive.

I have an aftermarket (EVOffer) automatic frunk and trunk systems fitted, with the frunk one being directly attached to the 12v battery. I presume there is some vampire drain from them, is it possible my 12v failed prematurely because of it?

Also between now and then should I leave my frunk unlatched or any other tips?
Leave a door open if the 12 volt is dead

EV offer did a video on how much drain the frunk has and it is apparently virtually nothing. They showed the measurements live. No idea if true or accurate. But no issues with me yet.
 
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Durzel

Well-Known Member
Jul 17, 2019
5,397
4,581
Bath, UK
It’s not dead yet, I’ve just had that notification to arrange service (thankfully, rather than finding it dead).

I’m not sure what leaving a door open would do? Wouldn’t it make more sense to leave the frunk open (just sat on the latch, not actually open fully)? Also my car lives outside and it’s due to rain the next few days :(
 
Also between now and then should I leave my frunk unlatched or any other tips?
Put the car in Sentry Mode during your trip whenever you stop, so that it never sleeps. Also, don't leave the frunk unlatched, just make sure you can unlatch it if the battery dies. That's what the 12V port in the bumper is for.


You should be getting ample warning to replace the 12V battery though. The reason people weren't was probably because of a software bug (which Tesla has a lot of). So just be prepared and have a device that lets you pop the frunk if the battery dies (a 12V battery or jump starter).
 
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Put the car in Sentry Mode during your trip whenever you stop, so that it never sleeps. Also, don't leave the frunk unlatched, just make sure you can unlatch it if the battery dies.

I was under the impression that if Sentry is activated, the car will not sleep and that a failing or dead 12 volt battery will not leave a driver locked out and stranded, thus eliminating the need for a jump start. Am I misinformed on that?
 
For a lot of detected 12V issues now, the car puts itself in always awake mode, same as sentry.

Interesting, I did not know that. I do remember a lot of comments over a year ago from people who were stranded and the solution offered was to pop the frunk with a 9 volt battery that was stored in the tow hook recess so the 12 volt could be accessed and jumped. I also remember that Tesla was working on a more reliable 12 volt failure warning message but I had not heard about that awake mode.
 
Curious... Is the likelihood of the 12V battery failing a function of how much you drive? For example, if you drive your car only 15k miles total over 4 years is the 12V battery less likely to fail than if you drive the car 80k miles over 4 years?
Not always a direct correlation, but a Tesla that is driven less is probably more likely to need a new 12v sooner because it spends more time "asleep" and perhaps doesn't get charged as much. The car charges the 12v anytime the car is awake, and periodically wakes up from "sleep" to do the same.
 
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Curious... Is the likelihood of the 12V battery failing a function of how much you drive? For example, if you drive your car only 15k miles total over 4 years is the 12V battery less likely to fail than if you drive the car 80k miles over 4 years?

We have 4 people in the office bought Model 3 AWD back in 2018. Some drove like 5000 miles per year, other could be 20,000 miles. Everything got the replace 12V message this year within 3 months of each others and all before 4 years. It's almost like it is on a timer.
 
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