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Why Tesla’s lead acid 12V battery needs to be lithium-ion based
It’s a prominent issue surrounding the electric vehicle market that the old-school lead acid battery just isn’t appropriate for new technology vehicles. Many users of electric vehicles, especially Tesla owners, have cited concerns with the poor performance of their 12V or low-voltage battery, oftentimes requiring annual replacement.
In contrast, a lead acid battery in a traditional internal combustion engine (ICE) vehicle generally has a 4 year life-cycle, but why?
RELATED: Tesla Model S 12V Lithium-Ion battery replacement (up to 70% lighter, 4x life)
First off, some of the most important factors to consider in longevity of a battery are “cycle-life”, environmental conditions, discharge/charge rates and calendar-life; cycle-life is how many times the battery can be drained and recharged in its life. Environmental conditions include temperature and humidity. Discharge/charge rates are the amperages going out of and into the battery respectively.
There are two major differences between the way an ICE vehicle uses its 12V battery and the way an EV uses its 12V battery:
“OFF” state discharge and cycling frequency
ICE Vehicle: generally has a very low 12V load while the vehicle is in the “off” state, often this load doesn’t exceed a few watts and doesn’t present a major challenge for the 12V battery to maintain.
Electric Vehicle: The 12V load while in the off-state is often much higher due to advanced computer systems that are running to maintain the high-voltage battery, keep vehicle “connected” (all EV have some remote access features), maintain charging and BMS (Battery Management System) communications, etc. In fact a Tesla Model S/X puts about 50 Watts of load on the 12V system when the vehicle is in the “off” state. 50 Watts equals about 4.5 Amps of discharge on the 12V battery, this drains the battery down relatively rapidly and requires the 12V battery be “recharged” by the high-voltage battery regularly, this usage pattern results in many cycles being placed on the battery.
“ON” state utilization and purpose
ICE Vehicle: The 12V battery is used to initiate the ICE (start the car) and is designed for putting out large amounts of current to accommodate this process. Once an ICE vehicle is in the “on” state, it relies on an alternator to power all of the 12V sub-systems and also maintain the voltage of the 12V battery.
Electric Vehicle: The 12V is subjected to (practically) no additional load while the vehicle is being turned “on”, and although most vehicles are designed with DC/DC converters (which act as alternators) it is often an engineering design choice to reduce load on the DC/DC converter by minimizing the frequency with which it is utilized. This also extends the driving range of the vehicle because none of the precious high-voltage battery capacity is being shunted to non-driving tasks. Due to this usage profile the 12V battery is subjected to relatively low discharge and recharge currents.
When you combine the high number of cycles and the low current requirements of the electric vehicle 12V battery system you arrive at a completely different battery need than that of an ICE vehicle. Lead Acid batteries are very good at high discharge and low cycle count life-styles, this is their bread and butter and this is where they last a long time and provide the most bang for the buck (cheap cost and decent product life-cycle), but they aren’t lasting in electric vehicles.
The electric vehicle 12V battery system is one that is best suited by a battery capable of tremendous cycle-life as the main design goal. The battery chemistry that suits this usage scenario best? Lithium! Lithium battery technology is specifically very good at being cycled many times and continuing to provide minimal capacity loss and degradation. This, along with reduced weight, is why these batteries are used for the high-voltage battery packs, cell-phones, laptops, medical equipment and cars where batteries are being cycled frequently and longevity is important.
Editor’s note: This post was submitted into our network by Tesla Model S owner Sean Scherer. Having suffered an unfortunate incident in his Model S that left him stranded because of a faulty 12V battery, Sherer began on a mission to create a lithium-ion based 12V battery solution that was not only more reliable than the traditional lead acid battery, but better suited for the demands of a Tesla Model S, Model X, and electric vehicles in general. He began BattMobile Batteries, who have made it their mission to improve adoption of electric vehicles by solving some of the small details that has been missed by EV manufacturers.
We’ve also included a video tutorial on how to replace the Model S 12V battery.
News
Anti-Tesla union leader ditches X, urges use of Threads instead
Tesla Sweden and IF Metall have been engaged in a bitter dispute for over two years now.
Marie Nilsson, chair of Sweden’s IF Metall union and a prominent critic of Tesla, has left X and is urging audiences to follow the union on Meta’s Threads instead.
Tesla Sweden and IF Metall have been engaged in a bitter dispute for over two years now.
Anti-Tesla union leader exits X
In a comment to Dagens Arbete (DA), Nilsson noted that her exit from X is not formally tied to IF Metall’s long-running labor dispute with Tesla Sweden. Still, she stated that her departure is affected by changes to the platform under Elon Musk’s leadership.
“We have stayed because many journalists pick up news there. But as more and more people have left X, we have felt that the standard has now been reached on that platform,” she said.
Jesper Pettersson, press officer at IF Metall, highlighted that the union’s departure from X is only indirectly linked to Tesla Sweden and Elon Musk. “Indirectly it does, since there is a lot of evidence that his ownership has caused the change in the platform to be so significant.
“We have nevertheless assessed that the platform had value for reaching journalists, politicians and other opinion leaders. But it is a microscopic proportion of the public and our members who are there, and now that value has decreased,” Petterson added.
IF Metall sees Threads as an X alternative
After leaving X, IF Metall has begun using Threads, Meta’s alternative to the social media platform. The union described the move as experimental, noting that it is still evaluating how effective the platform will be for outreach and visibility.
Pettersson acknowledged that Meta also does not operate under Sweden’s collective bargaining model, but said the union sees little alternative if it wants to remain visible online.
“In a perfect world, all large international companies would be supporters of the Swedish model when they come here. But unfortunately, the reality is not like that. If we are to be visible at all in this social media world, we have to play by the rules of the game. The alternative would be to become completely invisible, and that would not benefit our members,” he said.
Despite many recent rumors and various reports, Elon Musk confirmed today that SpaceX is not developing a phone based on Starlink, not once, but twice.
Today’s report from Reuters cited people familiar with the matter and stated internal discussions have seen SpaceX executives mulling the idea of building a mobile device that would connect directly to the Starlink satellite constellation.
Musk did state in late January that SpaceX developing a phone was “not out of the question at some point.” However, He also said it would have to be a major difference from current phones, and would be optimized “purely for running max performance/watt neural nets.”
Not out of the question at some point. It would be a very different device than current phones. Optimized purely for running max performance/watt neural nets.
— Elon Musk (@elonmusk) January 30, 2026
While Musk said it was not out of the question “at some point,” that does not mean it is currently a project SpaceX is working on. The CEO reaffirmed this point twice on X this afternoon.
Musk said, “Reuters lies relentlessly,” in one post. In the next, he explicitly stated, “We are not developing a phone.”
Reuters lies relentlessly
— Elon Musk (@elonmusk) February 5, 2026
We are not developing a phone
— Elon Musk (@elonmusk) February 5, 2026
Musk has basically always maintained that SpaceX has too many things going on, denying that a phone would be in the realm of upcoming projects. There are too many things in the works for Musk’s space exploration company, most notably the recent merger with xAI.
SpaceX officially acquires xAI, merging rockets with AI expertise
A Starlink phone would be an excellent idea, especially considering that SpaceX operates 9,500 satellites, serving over 9 million users worldwide. 650 of those satellites are dedicated to the company’s direct-to-device initiative, which provides cellular coverage on a global scale.
Nevertheless, there is the potential that the Starlink phone eventually become a project SpaceX works on. However, it is not currently in the scope of what the company needs to develop, so things are more focused on that as of right now.
Tesla has added a notable improvement to its Dashcam feature after complaints from owners have pushed the company to make a drastic change.
Perhaps one of the biggest frustrations that Tesla owners have communicated regarding the Dashcam feature is the lack of ability to retain any more than 60 minutes of driving footage before it is overwritten.
It does not matter what size USB jump drive is plugged into the vehicle. 60 minutes is all it will hold until new footage takes over the old. This can cause some issues, especially if you were saving an impressive clip of Full Self-Driving or an incident on the road, which could be lost if new footage was recorded.
This has now been changed, as Tesla has shown in the Release Notes for an upcoming Software Update in China. It will likely expand to the U.S. market in the coming weeks, and was first noticed by NotaTeslaApp.
The release notes state:
“Dashcam Dynamic Recording Duration – The dashcam dynamically adjusts the recording duration based on the available storage capacity of the connected USB drive. For example, with a 128 GB USB drive, the maximum recording duration is approximately 3 hours; with a 1 TB or larger USB drive, it can reach up to 24 hours. This ensures that as much video as possible is retained for review before it gets overwritten.”
Tesla Adds Dynamic Recording
Instead of having a 60-minute cap, the new system will now go off the memory in the USB drive. This means with:
- 128 GB Jump Drive – Up to Three Hours of Rolling Footage
- 1TB Jump Drive – Up to 24 Hours of Rolling Footage
This is dependent on the amount of storage available on the jump drive, meaning that if there are other things saved on it, it will take away from the amount of footage that can be retained.
While the feature is just now making its way to employees in China, it will likely be at least several weeks before it makes its way to the U.S., but owners should definitely expect it in the coming months.
It will be a welcome feature, especially as there will now be more customization to the number of clips and their duration that can be stored.
Anti-Tesla union leader ditches X, urges use of Threads instead
Elon Musk confirms SpaceX is not developing a phone
