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

[joebruin77]

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

 

[lasdj]

I still have my original 12v on my M3 18 LR. Only 27k miles but was wondering the same, should I get it replaced before my warranty expire in April of this yr? I wasn't sure if mobile will change it if I don't have any errors currently in my car.

 

[SilverString]

I have a similar concern with my MS which is nearly 3 years old. I have replaced lots of ICE 12 volt batteries, but doing this in a Tesla is not so simple. I am wondering if extreme temperature exposure plays a role in earlier failures.

 

[Shelburne]

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.

 

[medphys3]

Personally, I carry a 9v battery and a set of jumper cables just like in my other cars in case the battery fails. I wouldn’t proactively change it.

*I do have a battery monitor/alarm on mine which will sound if the voltage drops to below 12.2VDC (which it does frequently when the car powers up) just to potentially have a warning just in case.



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[mspohr]

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.

My 2015 Model S gave me a warning of low 12v battery (after 6 years of use). Had it replaced a week later. No problem.

 

[Flybyglass]

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.

It does. Sometimes it only warns with little time remaining.

 

[Wildbill]

I recently had to have my 12V battery replaced. My Model 3 did give me a warning that the battery needed to be replaced, but I did not know that I have only few days to replace it before the car shuts down. Tesla Mobile Service came and replaced it under warranty. He told me that as soon as I get the warning on 12V battery low, I should drive it to a service station.

An alternative is to proactively replace the 12V with a lithium 12V battery which will last much longer:

12V LFP Batteries for Tesla and EVs | Ohmmu | United States

The best 12V LFP replacement batteries for Tesla, Toyota Prius, and other EVs. Get longer life, lighter weight, and better performance with Ohmmu - upgrade your 12V battery today!

www.ohmmu.com

 

[jwharnish]

I still have my original 12v on my M3 18 LR. Only 27k miles but was wondering the same, should I get it replaced before my warranty expire in April of this yr? I wasn't sure if mobile will change it if I don't have any errors currently in my car.

I had my 12v battery checked out when it was in for a window regulator replacement. I had smelled a sulfur smell when car was in garage charging and asked Service to check it out. The said the battery was swollen and replaced in under warranty. 18 M3p.
Did this at about 2 1/2 year mark. Was concerned because I was heading out on a cross country trip and did not want the12 v failing on that trip.
Service was not going to replace 12v initially since no codes were noted, but tech did visual and went thru with the replacement.

 

[Adam3]

I replaced mine at the 2 year mark. The often die at 2-3 years so I dont think it is overkill.

 

[RayK]

I recently had to have my 12V battery replaced. My Model 3 did give me a warning that the battery needed to be replaced, but I did not know that I have only few days to replace it before the car shuts down. Tesla Mobile Service came and replaced it under warranty. He told me that as soon as I get the warning on 12V battery low, I should drive it to a service station.

An alternative is to proactively replace the 12V with a lithium 12V battery which will last much longer:

12V LFP Batteries for Tesla and EVs | Ohmmu | United States

The best 12V LFP replacement batteries for Tesla, Toyota Prius, and other EVs. Get longer life, lighter weight, and better performance with Ohmmu - upgrade your 12V battery today!

www.ohmmu.com

If you don't know, the Ohmmu lithium battery has its own potential problems. Sometimes Tesla issues a software update which alters the way the car charges the 12V battery OR changes the algorithm that is used to detect a possibliy failing 12V battery. The Ohmmu battery has its own internal battery management system and has different operating characteristics than the normal lead acid battery which can result in the car thinking there's a problem with battery. So far, Ohmmu has been issuing revisions to their battery, going so far as to let owners swap the earlier versions with an updated one. Seems like they are currently working on another update.

So yes, maybe the lithium battery will last "longer" than the factory one, but there's no guarantee it will be as trouble-free. My own 2018 LR with just over 22K miles is still on the original 12V battery. I was initially eager to replace it with the Ohmmu but now I'm on the fence.

 

[Jeremy3292]

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.

 

[tomas]

The lithium is 5x the price of std battery. I thought about it… for 10 minutes! The issue with any guidance on how long it will last is that charging and driving behavior as well as settings will impact draw on 12v and therefore cycles and lifespan. So my 2018 3 battery has lasted almost 4 years now, but YMMV and it’s probably time to change next time I service.

 

[tomas]

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 and theory but may not be.

ANYTHING the car does when parked uses 12v. So, sentry mode, summon standby, always connected… would all seem to cause higher 12v recharge cycles. Plus I suspect a lot of the features use 12v even when driving, as Something has to convert HV battery to a “usable” voltage for things like computer, cameras.,,

In other words… it gets Flogged!

 

[Jeremy3292]

ANYTHING the car does when parked uses 12v. So, sentry mode, summon standby, always connected… would all seem to cause higher 12v recharge cycles. Plus I suspect a lot of the features use 12v even when driving, as Something has to convert HV battery to a “usable” voltage for things like computer, cameras.,,

In other words… it gets Flogged!

True but the word on the street is that leaving your car sitting for a while and not driving it causes it to degrade more. In fact driving it more apparently extends the life.

 

[tomas]

True but the word on the street is that leaving your car sitting for a while and not driving it causes it to degrade more. In fact driving it more apparently extends the life.

Beware “word on street”. I have 2 model 3s that are almost 4 years old and are unused ~ half the year. Still on first 12v for both.

 

[RandyS]

I proactively replaced mine at just over 3 years and the original OEM battery had bulges in the case when I got it out...Dodged a bullet, I thought....

 

[pilotSteve]

Got a proactive notification on my Tesla app the 12v needed replacing on my 2016 S90D two weeks ago (that seems to me like pretty good life on the original battery AND notification before it failed!) so I scheduled service and had it replaced for $165 + $31 labor. Worth it to me to have SvC check tires, fluids, bulletins etc and do it while I waited.

 

[Thp3]

True but the word on the street is that leaving your car sitting for a while and not driving it causes it to degrade more. In fact driving it more apparently extends the life.

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…

 

[jjrandorin]

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 replaced mine proactively late last year, which was at about 3 years. I plan (if I still have the car) to replace it every 2 years since its only $85 for the part, and $129 total installed in my driveway by tesla.

I did it proactively after reading all the 12v threads here. Its cheap enough that its consumable on our cars.