Connect with us

Lifestyle

Understanding the Tesla 12V Battery Service Warning

Published

on

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

Advertisement

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.

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.

Advertisement

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?

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.

Advertisement

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.

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.

Advertisement

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

Advertisement
Comments

Elon Musk

The FCC just said ‘No’ to SpaceX for now

SpaceX is fighting the FCC for spectrum that could put satellites inside every smartphone.

Published

on

By

SpaceX was dealt a new setback on April 23, 2006 by the Federal Communications Commission (FCC) after the U.S. government agency dismissed the company’s petition to access a Mobile Satellite Service spectrum that would allow direct-to-device (D2D) capabilities.

The FCC regulates communications by radio, television, wire, and cable, which also includes regulating D2D technology that lets your existing smartphone connect directly to a satellite orbiting Earth, the same way it would connect to a cell tower.

Elon Musk’s SpaceX has been building toward this through its Starlink Mobile service, formerly called Direct-to-Cell, in partnership with T-Mobile. The service officially launched on July 23, 2025, starting with messaging and expanding to broadband data in October of that year.

T-Mobile Starlink Pricing Announced – Early Adopters Get Exclusive Discount

Advertisement

It’s worth noting that SpaceX is not alone in this race. AT&T and Verizon have their own satellite texting deals with AST SpaceMobile, while Verizon separately offers free satellite texting through Skylo on newer phones.

The regulatory foundation for all of this dates to March 14, 2024, when the FCC adopted the world’s first framework for what it called Supplemental Coverage from Space, allowing satellite operators to lease spectrum from terrestrial carriers and fill gaps in their coverage. On November 26, 2024, the FCC granted SpaceX the first-ever authorization under that framework, approving its partnership with T-Mobile to provide service in specific frequency bands. SpaceX then went further, completing a roughly $17 billion acquisition of wireless spectrum from EchoStar, which gave it the ability to negotiate with global carriers more independently.

Starlink’s EchoStar spectrum deal could bring 5G coverage anywhere

This recent ruling by the FCC blocked SpaceX from going further, protecting incumbent spectrum holders like Globalstar and Iridium. But the market momentum is already in motion. As Teslarati reported, SpaceX is targeting peak speeds of 150 Mbps per user for its next generation Direct-to-Cell service, compared to roughly 4 Mbps today, which would bring satellite connectivity close to standard carrier performance.

Advertisement

With a reported IPO targeting a $1.75 trillion valuation on the horizon, each spectrum fight, carrier deal, and regulatory win or loss now carries weight beyond just connectivity. SpaceX is quietly becoming the infrastructure layer underneath the phones of millions of people, and the FCC’s next move will help determine how much further that reach extends.

FCC Satellite Rule Makings can be found here.

Continue Reading

Elon Musk

Elon Musk talks Tesla Roadster’s future

Elon Musk confirmed the Roadster as Tesla’s last manually driven car, with a debut coming soon.

Published

on

By

Tesla Roadster driving along sunset cliff (Credit: Grok)

During Tesla’s Q1 2026 earnings call on April 22, Elon Musk made a brief but notable comment about the long-awaited next generation Roadster while describing Tesla’s future vehicle lineup. “Long term, the only manually driven car will be the new Tesla Roadster,” he said. “Speaking of which, we may be able to debut that in a month or so. It requires a lot of testing and validation before we can actually have a demo and not have something go wrong with the demo.”

That single statement is the entire Roadster update from yesterday’s call, and while it represents another timeline shift, it comes as no surprise with Tesla heads-down-at-work on the mass rollout of its Robotaxi service across US cities, and the industrial scale production of the humanoid Optimus.

The fact that Musk specifically framed the Roadster as the last manually driven Tesla is significant on its own. As the rest of the lineup moves toward full autonomy, the Roadster becomes something rare in the Tesla-sphere by keeping the driver in control. Driving enthusiasts who buy a $200,000 supercar are not doing so to be passengers. They want the physical connection to the road, the feel of acceleration under their own input, and the experience of controlling something with that level of performance. FSD, however capable it becomes, removes that entirely. The Roadster signals that Tesla understands this distinction and is building a car specifically for the people who consider driving itself the point.

Tesla isn’t joking about building Optimus at an industrial scale: Here we go

Advertisement

The specs for the Roadster Musk has teased over the years are genuinely unlike anything in production. The base model targets 0 to 60 mph in 1.9 seconds, a top speed above 250 mph, and up to 620 miles of range from a 200 kWh battery. The optional SpaceX package takes it further, rumored to add roughly ten cold gas thrusters operating at 10,000 psi, borrowed directly from Falcon 9 rocket technology. With thrusters, Musk has claimed 0 to 60 mph in as little as 1.1 seconds. In a 2021 Joe Rogan interview he went further, stating “I want it to hover. We got to figure out how to make it hover without killing people.” Tesla filed a patent for ground effect technology in August 2025, suggesting the hover concept has not been abandoned. The starting price remains $200,000, with the Founders Series requiring a $250,000 full deposit. Some reservation holders placed those deposits in 2017 and are approaching a full decade of waiting.

With production now targeted for 2027 or 2028 at the earliest, the Roadster remains Tesla’s most audacious promise and its longest-running delay. But if what Musk is testing lives up to even half of what he has described, the demo alone should be worth waiting for.

Continue Reading

Elon Musk

Tesla isn’t joking about building Optimus at an industrial scale: Here we go

Tesla’s Optimus factory in Texas targets 10 million robots yearly, with 5.2 million square feet under construction.

Published

on

By

Tesla’s Q1 2026 Update Letter, released today, confirms that first generation Optimus production lines are now well underway at its Fremont, California factory, with a pilot line targeting one million robots per year to start. Of bigger note is a shared aerial image of a large piece of land adjacent to Gigafactory Texas, that Tesla has prominently labeled “Optimus factory site preparation.”

Permit documents show Tesla is seeking to add over 5.2 million square feet of new building space to the Giga Texas North Campus by the end of 2026, at an estimated construction investment of $5 billion to $10 billion. The longer term production target for that facility is 10 million Optimus units per year. Giga Texas already sits on 2,500 acres with over 10 million square feet of existing factory floor, and the North Campus expansion is being built to support multiple projects, including the dedicated Optimus factory, the Terafab chip fabrication facility (a joint Tesla/SpaceX/xAI venture), a Cybercab test track, road infrastructure, and supporting facilities.

Credit: TESLA

Texas makes strategic sense beyond the existing infrastructure. The state’s tax structure, lower labor costs relative to California, and the proximity to Tesla’s AI training cluster Cortex 1 and 2, both located at Giga Texas and now totaling over 230,000 H100 equivalent GPUs, means the Optimus software stack and the factory producing the hardware will share the same campus. Tesla’s Q1 report also confirmed completion of the AI5 chip tape out in April, the inference processor designed specifically to power Optimus units in the field.

As Teslarati reported, the Texas facility is intended to house Optimus V4 production at full scale. Musk told the World Economic Forum in January that Tesla plans to sell Optimus to the public by end of 2027 at a price between $20,000 and $30,000, stating, “I think everyone on earth is going to have one and want one.” He has previously pegged long term demand for general purpose humanoid robots at over 20 billion units globally, citing both consumer and industrial use cases.

Advertisement
Continue Reading