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Understanding the Tesla 12V Battery Service Warning

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During the time when I was sitting on the sideline waiting patiently for delivery of my Model S, I read up on pretty much anything and everything related to the vehicle. I remember reading about 12V battery failures on the Model S, something Elon himself even commented on during one of the earnings calls.

RELATED: Tesla Model S 12V Lithium-Ion battery replacement (up to 70% lighter, 4x life)

It was reported that Tesla had chosen a poor vendor for the 12V battery which impacted early Model S owners but apparently this issue is still happening across later production vehicles. My Model S as well as several others that I personally know of received the 12V battery service indicator. For me this took place after 7 months and 18,000 miles of ownership.

Purpose of the Tesla 12V battery

Model S Battery

Tesla Model S 12V Battery (source: TMC forum)

The 12V battery in the Model S performs many of the same duties as it would in any internal combustion engine (ICE) car.The connections to the 12V battery on a Model S appear to be a bit more complex than in a traditional ICE as seen in the following picture (source: TMC forum).

RELATED: Why Tesla’s lead acid 12V battery needs to be lithium-ion based

The 12V battery maintains power for critical systems when the main battery pack is damaged or disabled. It powers the hazard lights, airbags, door locking and unlocking operations, as well as other critical componets of the Model S. The 12V battery also ensures that electronics are “awake” and listening to the key FOB in order to automatically lock and unlock the vehicle based on proximity. It also allows the car to maintain its 3G connection for remote access when the rest of the vehicle is powered off. If the 12V battery happens to fail, it will isolate the main battery pack from the car and prevent charging. This is a safety feature of the Model S designed to help protect first responders in the event of an accident.

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What does my warning mean?

The “12V Battery Needs Service” warning can indicate a number of problems and the only way to truly understand the reason for the alert is to call Tesla Service (they’re available 24×7) and have them pull the logs. This is something that Tesla service can diagnose remotely.

Tesla 12V battery terminal

Tesla 12V battery terminal

In severe cases Tesla Service will tell you to stop driving the car, but generally it’s an indication that the voltage level has dropped below a certain threshold but the vehicle can continue to operate normally until replaced. In the rare event that the the 12V battery dies while driving, the car will become disabled and will require a jump start to power on again. Our friend Kman has a good video on getting access to the terminals behind the nosecone to jump start the 12V, but please consult Tesla service and take caution before attempting this on your own.

Depending on the severity of the issue, there may be a 2-3 week lead time before Tesla Service replaces the 12V battery.

Many owners manage to get the battery replaced quickly, but in my case a busy Tesla Service Center combined with the fact that it was Thanksgiving holiday during a snowy New England week, had me driving with the warning light on for almost 2 weeks (about 1,000 miles) without encountering any issues.

Another interesting point to note is that Tesla may call you before you even see 12V battery service warning. Multiple owners have reported this proactive stance in advance of a warning which is great to see. Evidently Tesla’s early warning threshold is supersedes the trigger that kicks off the dash indicator.

Why are the 12V batteries failing?

Some owners are on their 3rd 12V battery already. Many others are reporting failures at the 1 year mark. In ICE cars you can normally expect about 4 years of life before needing to replace the 12V battery which begs the question – why are Tesla 12V batteries failing?

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Some of the failures have been in the DC to DC converter that charges the 12V battery through the main battery pack. That converter can be seen as an equivalent to the alternator in your traditional ICE car. However, this doesn’t seem to be the main cause of the 12V battery failures. Current conjecture is that vampire load and the excessive strain on the 12V are causing the reliability issues.

Tesla may have a lingering design issue in their use of the 12V battery.

From my reading, I think they upgraded the quality of the battery in the earlier models but we’re still facing the same underlying design issue in the way the 12V is stressed. Can Tesla fix the way the 12V battery is used with software updates alone? We don’t know, but fortunately they’re taking care of all of the replacements in the meantime. Unless they can address it remotely via software updates, there could be a factory “recall” brewing (and I use this term loosely).

Either way, Tesla should be more upfront about these issues and let owners know what they’re doing to address the underlying problem.

Getting the 12V battery serviced

From everthing I’ve heard and experienced through my own Model S, the replacement including labor and parts is 100% covered by Tesla.

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Tesla Service can handle the replacement at your location, but given the poor weather conditions here in New England, I opted to have them pick up my Model S and do the replacement in the comfort of their own Service Center. They were able to service it within the same day, and to Tesla fashion they also updated/fixed a bunch of other minor things for free, while at it.

Summary

The 12V battery is a relatively inexpensive part in the Model S and is fairly simple to replace, but the bigger concern is why they seem to be failing so quickly. It isn’t a major issue for now but certianly something we should continue monitoring as concerned Model S owners.

I’ve started a poll over on TMC to see what kind of failure rate we’re seeing on the 12V battery so feel free to contribute to it or use it as a way monitor progress. So far over 75% of respondents have had their 12V battery replaced within 2 years.

"Rob's passion is technology and gadgets. An engineer by profession and an executive and founder at several high tech startups Rob has a unique view on technology and some strong opinions. When he's not writing about Tesla

Lifestyle

Tesla brings perhaps the coolest interior feature to cars in latest update

Tesla adds on to the “fun” aspect of its vehicles.

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Credit: Tesla

Tesla has brought perhaps the coolest interior feature to its cars in a new update that is rolling out to vehicles now.

The feature will require a newer vehicle that has interior ambient lighting, which is present on the new Model S, Model X, Model 3 “Highland,” and Model Y “Juniper.” The Cybertruck also has ambient lighting strips throughout.

Tesla Model Y’s ambient lighting design changes revealed in leaked video

With the Version 2025.26+ Software Update, Tesla is rolling out a new “Sync Accent Lights w/ Music” feature, which is available on the Tesla Toybox:

To enable the feature, you’ll access the Toybox, choose “Light Sync,” and then choose “Sync Accent Lights w/ Music.”

Although it does not improve the performance of the vehicle, it is yet another example of Tesla making one of the coolest cars out there. This is truly a cool add-on that can be used to impress your friends and family.

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xAI, Musk Foundation helps schools near Memphis supercomputer site

Reports of xAI and the Musk Foundation’s work were recently posted by local news media.

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xAI-supercomputer-memphis-environment-pushback
(Credit: xAI)

Elon Musk’s artificial intelligence startup xAI and the Musk Foundation have been supporting Memphis-Shelby County Schools with HVAC repairs and facility upgrades, while also funding youth programs for students in the area. 

Reports of xAI and the Musk Foundation’s work were recently posted by local news media.

xAI’s school visits lead to facility repairs

Representatives from xAI visited John P. Freeman Optional School, Fairley High School, and Westwood High School, all of which are located near its Colossus supercomputer site, to assess HVAC systems, plumbing, gym facilities, and athletic fields. The visits resulted in a list of priority repairs, some of which were completed in April and May.

In addition to the repairs, xAI also shared a number of initiatives that are planned for students in the area, as stated in a Commercial Appeal report.

“xAI is working on providing STEM workshops for local students, donating equipment to technical training programs, and supporting job fairs to boost employment opportunities. These initiatives reflect xAl’s commitment to fostering education and economic growth in Memphis,” xAI noted in a statement.

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Musk Foundation donation

Apart from xAI, the Musk Foundation also donated $350,000 to the Boys & Girls Clubs of Greater Memphis, enabling the reopening of two club sites located at Booker T. Washington High School and Westwood High School. Both locations had closed earlier this year due to lapses in funding. As per xAI, the Musk Foundation’s donation allows clubs to reopen for almost 1,000 students. 

The donation will fund staffing, supplies, and transportation, among others. “Kids are the future of humanity,” Elon Musk said in a statement, adding that students need “every chance to shoot for the stars.”

“We’re honored to support the Boys & Girls Clubs of Greater Memphis in reopening these sites, giving kids in underserved communities the tools to build brighter futures,” Musk said.

The gift was praised by local officials, including Boys & Girls Clubs board chair Michael Garriga, who stated that the “commitment will ensure the youth of our community have the opportunities they need to develop their skills and talents to become successful students and future citizens.”

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EV fans urge Tesla to acquire Unplugged Performance for edge in fleet and security industry

Unplugged Performance has built a name for itself by producing performance upgrades for Tesla vehicles.

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Credit: Unplugged Performance

A growing number of Tesla enthusiasts and longtime community voices are calling on the electric vehicle maker to acquire Unplugged Performance, a California-based aftermarket company best known for tuning Tesla vehicles and developing specialized government fleet solutions under its UP.FIT division.

The idea was once considered a niche proposal among EV fans, but it is now gaining serious attention not just as a performance play but as a strategic move to deepen Tesla’s roots in the fleet and security industry. 

A strategic fit

Unplugged Performance has built a name for itself by producing performance upgrades for Tesla vehicles, from track-optimized components to visual and aerodynamic upgrades. But in recent years, its UP.FIT division has pivoted toward a more functional future by outfitting Tesla vehicles like Model Ys for police, military, and government use.

That work has sparked growing calls for closer collaboration with Tesla, especially as the EV maker increasingly leans into autonomy, AI, and fleet services as core components of its next chapter.

“I posted this four years ago, but I think it’s more true now than ever,” wrote Whole Mars Catalog, a well-known Tesla investor and FSD Beta tester, on X. “Tesla should buy Unplugged. But not just as a Performance division. What they are doing with UP.FIT unlocks large government and commercial fleet purchases that can improve utilization.”

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Tesla fans such as shareholder Sawyer Merritt echoed the sentiment, calling Unplugged a “great fit within Tesla.” adding, “They are literally located directly next to Tesla’s design studio in Hawthorne.”

Enabling the next wave

Supporters of the idea noted that integrating Unplugged into Tesla’s corporate structure could help accelerate the adoption of autonomous technologies in government sectors. With UP.FIT patrol cars already in use across some U.S. police departments, Tesla fans envisioned a future where self-driving Teslas could potentially revolutionize law enforcement, search-and-rescue, and public service logistics.

“Just imagine how autonomous patrol cars could transform policing and bring us into a safer future,” the veteran FSD tester wrote.

The benefits could also extend to Tesla’s existing consumer base. “They also have some incredible products in the works that I think will appeal to many ordinary Tesla drivers — not just those looking for performance or mods. Stuff that’s so good it should have come straight from the design studio next door,” Whole Mars Catalog noted.

Unplugged Performance, founded in 2013, shares not just a product vision with Tesla, but also geography. Its Hawthorne headquarters sits directly adjacent to Tesla’s design studio, and the two companies have maintained a close working relationship over the years. The aftermarket firm has long positioned itself as a “mission-aligned” partner to Tesla.

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In response to the recent calls for acquisition, Unplugged Performance acknowledged the support from the community. “Our very existence is to support the Tesla mission with @UpfitTesla and @UnpluggedTesla,” Unplugged CEO Ben Schaffer posted on X. “We love working with Tesla and are grateful for the community’s support since 2013!”

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