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

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I bought a 51R at my local Sams Club when it went on sale for $85, just before a long trip this past Fall, as my car was getting close to 3yrs old. I also carry a 9V in my pocket and have a Noco charger in the frunk, just in case. So far, 37 months, and almost 30k miles, and it's fine. I also have a 12v tester to check it. I'd rather have spent the $85 than be stranded somewhere and have to be towed. Time is money too!
 
My 12v battery will have been in use for 4 years (in 3 more months) and I've driven 72,901 miles. I plan to replace it only when I get a warning message from the car or when it dies. I can easily pop open the frunk with the A23 battery I've hidden behind the tow hook cover and can jump start myself with the portable jump starter I carry around in the frunk. If I have to replace the battery, I can buy a group size 51R battery that will work at Walmart (walking distance from my work) or at any of my local auto parts stores. I'm not a fan of replacing something that works fine if it's not going to inconvenience me much when it fails.

Edit to add that in the almost 4 years of caring around my portable jump starter, I've used it about 6 times on other people's cars (strangers and co-workers) to jump weak or dead batteries. In 2 cases I used it to limp vehicles with a dead alternator and battery to a parts store. I'm a fan of doing things myself. Which is why I also carry a plug kit and air compressor in case of flat tire (which haven't had to use on my own car yet but have used on others).
 
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The only "major" service issue I have ever had with my 2018 P3D is that I had to have the 12v battery replaced after about 2 1/2 years. Even though it was covered under warranty, I consider it a major issue because it rendered the car undriveable and it had to be towed. At that time, there was no warning that the battery was weak. One day, the car just would not power on and I had to have it towed to the nearest SC.

My question is, is it a good idea to have the 12v battery replaced periodically even if there is no sign of a problem? If so, when would you have it replaced? Every 2 years? Every 18 months?

Just curious what other Tesla Model 3 drivers are doing in regards to 12v battery replacement. Thank you!

Joebruin77
2018 Model 3 here with 132k miles on the odometer. I'm on my 4th year, I haven't changed my 12 volt battery yet. What do you think you're accomplishing by changing it before the car calls for it?
 
I’m still trying to figure out what causes the 12V battery to go through more cycles and die prematurely. What are the causes?

For only $100 mobile service will replace it, so it seems like a no brainer to just do it every two years.

The Ohmmu has many problems itself and sounds like a good idea in theory but may not be.
100$ cost replacement + cost of battery? How much was the cost of the battery alone ?thanks
 
The only "major" service issue I have ever had with my 2018 P3D is that I had to have the 12v battery replaced after about 2 1/2 years. Even though it was covered under warranty, I consider it a major issue because it rendered the car undriveable and it had to be towed. At that time, there was no warning that the battery was weak. One day, the car just would not power on and I had to have it towed to the nearest SC.

My question is, is it a good idea to have the 12v battery replaced periodically even if there is no sign of a problem? If so, when would you have it replaced? Every 2 years? Every 18 months?

Just curious what other Tesla Model 3 drivers are doing in regards to 12v battery replacement. Thank you!

Joebruin77
I did a proactive change at about 28 months for exactly the reasons you noted . getting stuck in the middle of nowhere with the logistical nightmare of towing. However, I understand Tesla are switching to LiIon batteries, so perhaps this is no longer necessary, as these tend to degenerate more gracefully.
 
100$ cost replacement + cost of battery? How much was the cost of the battery alone ?thanks
The cost for my Model 3 replacement including install was $111.25 with labor. $85 part. $26.25 labor. I will gladly pay this to do nothing than pay for it in the app.

For those that travel in a box don't worry. If you travel outside of the box way way far away, and don't like an avoidable inconvenience. Or those that say I won't pay a nickel sooner than I have to. I replace the battery every 3 years or 80-90k on both cars.

Does one have to do that? No. There are variables on how long after notification till one runs out of luck. I don't like to press my luck in the middle of Wyoming after leaving the Bread Board when it is cold as....I also wouldn't want to have to find the battery at some place, and tear out my frunk when it is blowing 35mph as the Autozone guy is stroking his beard watching me.

Recycling 12v batteries is one of the most mature recycling business. I don't feel one bit shameful, and won't have an issue unless I buy a bad battery.

To those who say it will never happen. Here's a picture in November 12th of last year at the Marshall supercharger this gent tearing out his front and replacing his 12 volt battery that had just died. He had bought one, and luckily had been driving around with it. So for those of you that say it can never happen or. I don't think it will ever happen to me. It does.
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38 months with original battery. Plan to keep that 12 volt battery while it is still under warranty. After the warranty runs out (Nov 2022) I plan on replacing it. Seems four years is about the average life for a car 12 volt battery. So a mix of frugal and proactive.
 
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My M3 is a 2019.. so it's 2.5 years now plus however long it say around waiting to be installed/delivered etc. Anyways.. I opened a ticket with Tesla for a proactive replacement explaining I was going on a 2K road trip in March and I wanted to proactively replace it instead of trying to do it on the road trip. I just got the verification for the appointment.. Est. is N/C.. covered by warranty. :) After hearing all the stories about lack of customer service, I was expecting to pay my 85 + dollars. So a pleasant surprise.
 
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I’m still trying to figure out what causes the 12V battery to go through more cycles and die prematurely. What are the causes?

For only $100 mobile service will replace it, so it seems like a no brainer to just do it every two years.

The Ohmmu has many problems itself and sounds like a good idea in theory but may not be.
When this issue first started appearing a couple of years ago, I checked out my 2018 M3p 12v to see what it's charge rate was during charging. The 12v battery was charging at 14.98v when the car was plugged and charging. Too high of a charge rate has been a reason 12v batteries fail in general. I have never read that this had any affect on the M3 12v battery lifespan, but after I had my battery replaced under warranty, I rechecked the charge rate and it was now at 13.85v.
I believe the 12v were being overcharged during charging, and there was a software change to lower the charge rate to extend the lifespan of the 12v batteries.
I believe this from my own testing and have not seen this as a published reason for the shorter lifespan of some M3 12v batteries. My battery was replaced due to being swollen. Too high of charge rate, too much gas internally, sulfur smell, all I feel was due to charge rate.
 
The car needs to be plugged in all the time it is parked to extend the 12V battery life. Or to say it backwards, I think the battery will wear out quicker if the car is parked by not plugged in.

Simple thermodynamics, if the parked car is plugged in the battery will have many small self charges. But if it is unplugged, then it will drain to a lower charge and when plugged in it will need more current. Bigger charge oscillations would likely charging capacity loss. Then over time the battery fails.

Only coincidental observations when people complain their battery dies. But I keep the cars plugged in as much as possible and this Spring I plan to replace the battery…
I don't think this is true. Whether the car is plugged in or not, the high voltage contactors open and everything runs on 12 vdc. When that gets low. the contactors close and the HVB charges the 12 vdc. Being plugged in just tops off the HVB periodically. I was warned of a deteriorating battery and it was about a month before it was replaced under warranty. I think the warning software has been improved.
 
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My 2019 M3 is 30 months old with 47K miles on it. I plan to drive it until 50k and if the battery has not died before then and thus under warranty then just replace and pay for it. From speaking with various people at the service center it sounds like getting 3 years out of a M3 12V is reasonable. After that you are asking for it.
 
It would be nice if Tesla, via a software update, could let you know in advance that your 12v battery will need replacement soon. That way we could all avoid anxiety over this issue.
As others pointed out, it does already. Unfortunately it's non-trivial to detect failures ahead of time. Sometimes it's over optimistic, sometimes it warns too early. It's not always accurate. The battery can be fine one day and then suddenly fail. It does not fail in a set pattern or gradually.
 
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The car needs to be plugged in all the time it is parked to extend the 12V battery life. Or to say it backwards, I think the battery will wear out quicker if the car is parked by not plugged in.

Simple thermodynamics, if the parked car is plugged in the battery will have many small self charges. But if it is unplugged, then it will drain to a lower charge and when plugged in it will need more current. Bigger charge oscillations would likely charging capacity loss. Then over time the battery fails.

Only coincidental observations when people complain their battery dies. But I keep the cars plugged in as much as possible and this Spring I plan to replace the battery…
The Chevy Bolt ( I believe) had an issue where it wouldn't charge the 12V if it wasn't plugged in. Tesla vehicles do not suffer from that. Anytime the 12V need charging, the contactors are closed and the 12V is charged - UNLESS the 12V is in failure mode, where charging could cause even larger problems.
 
The cost for my Model 3 replacement including install was $111.25 with labor. $85 part. $26.25 labor. I will gladly pay this to do nothing than pay for it in the app.

For those that travel in a box don't worry. If you travel outside of the box way way far away, and don't like an avoidable inconvenience. Or those that say I won't pay a nickel sooner than I have to. I replace the battery every 3 years or 80-90k on both cars.

Does one have to do that? No. There are variables on how long after notification till one runs out of luck. I don't like to press my luck in the middle of Wyoming after leaving the Bread Board when it is cold as....I also wouldn't want to have to find the battery at some place, and tear out my frunk when it is blowing 35mph as the Autozone guy is stroking his beard watching me.

Recycling 12v batteries is one of the most mature recycling business. I don't feel one bit shameful, and won't have an issue unless I buy a bad battery.

To those who say it will never happen. Here's a picture in November 12th of last year at the Marshall supercharger this gent tearing out his front and replacing his 12 volt battery that had just died. He had bought one, and luckily had been driving around with it. So for those of you that say it can never happen or. I don't think it will ever happen to me. It does.View attachment 759126View attachment 759114
12V replacement on a Model 3 is easy. One bolt. two connectors. One pop-out panel.

That's an S in your photo. Different replacement procedure.
 
12V replacement on a Model 3 is easy. One bolt. two connectors. One pop-out panel.

That's an S in your photo. Different replacement procedure.
Ok. Again. Is that something one might want to do or think about? Carry a socket wrench on a vacation or business call? Let alone in some places that are less than great. I will gladly pay a service center to something proactive. Having the know how doesn't mean one wants to do something or even think about it more than I have. Many forget that. Some like to do that.

Really for all that everyone goes on and on about EV's needing no maintenance. Why not just take care of something so simple and really so inexpensive. Should I start gathering the threads of dead 12v that drivers have ignored the warning? Or said I have 30 days or so?
 
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If you want to replace with one from Tesla, you might pre-order it because it doesn't seem to be something in stock. Mine was to be available 2 weeks back or so but now it's early Feb. 40K+ miles, nearly 4 years old. Not feeling that lucky so will replace when I can