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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
Tesla confirms Robotaxi expansion plans with new cities and aggressive timeline
Tesla plans to launch in Dallas, Houston, Phoenix, Miami, Orlando, Tampa, and Las Vegas. It lists the Bay Area as “Safety Driver,” and Austin as “Ramping Unsupervised.”
Tesla confirmed its intentions to expand the Robotaxi program in the United States with an aggressive timeline that aims to send the ride-hailing service to several large cities very soon.
The Robotaxi program is currently active in Austin, Texas, and the California Bay Area, but Tesla has received some approvals for testing in other areas of the U.S., although it has not launched in those areas quite yet.
However, the time is coming.
During Tesla’s Q4 Earnings Call last night, the company confirmed that it plans to expand the Robotaxi program aggressively, hoping to launch in seven new cities in the first half of the year.
Tesla plans to launch in Dallas, Houston, Phoenix, Miami, Orlando, Tampa, and Las Vegas. It lists the Bay Area as “Safety Driver,” and Austin as “Ramping Unsupervised.”
These details were released in the Earnings Shareholder Deck, which is published shortly before the Earnings Call:
🚨 BREAKING: Tesla plans to launch its Robotaxi service in Dallas, Houston, Phoenix, Miami, Orlando, Tampa, and Las Vegas in the first half of this year pic.twitter.com/aTnruz818v
— TESLARATI (@Teslarati) January 28, 2026
Late last year, Tesla revealed it had planned to launch Robotaxi in Las Vegas, Phoenix, Dallas, and Houston, but Tampa and Orlando were just added to the plans, signaling an even more aggressive expansion than originally planned.
Tesla feels extremely confident in its Robotaxi program, and that has been reiterated many times.
Although skeptics still remain hesitant to believe the prowess Tesla has seemingly proven in its development of an autonomous driving suite, the company has been operating a successful program in Austin and the Bay Area for months.
In fact, it announced it achieved nearly 700,000 paid Robotaxi miles since launching Robotaxi last June.
🚨 Tesla has achieved nearly 700,000 paid Robotaxi miles since launching in June of last year pic.twitter.com/E8ldSW36La
— TESLARATI (@Teslarati) January 28, 2026
With the expansion, Tesla will be able to penetrate more of the ride-sharing market, disrupting the human-operated platforms like Uber and Lyft, which are usually more expensive and are dependent on availability.
Tesla launched driverless rides in Austin last week, but they’ve been few and far between, as the company is certainly easing into the program with a very cautiously optimistic attitude, aiming to prioritize safety.
Investor's Corner
Tesla (TSLA) Q4 and FY 2025 earnings call: The most important points
Executives, including CEO Elon Musk, discussed how the company is positioning itself for growth across vehicles, energy, AI, and robotics despite near-term pressures from tariffs, pricing, and macro conditions.
Tesla’s (NASDAQ:TSLA) Q4 and FY 2025 earnings call highlighted improving margins, record energy performance, expanding autonomy efforts, and a sharp acceleration in AI and robotics investments.
Executives, including CEO Elon Musk, discussed how the company is positioning itself for growth across vehicles, energy, AI, and robotics despite near-term pressures from tariffs, pricing, and macro conditions.
Key takeaways
Tesla reported sequential improvement in automotive gross margins excluding regulatory credits, rising from 15.4% to 17.9%, supported by favorable regional mix effects despite a 16% decline in deliveries. Total gross margin exceeded 20.1%, the highest level in more than two years, even with lower fixed-cost absorption and tariff impacts.
The energy business delivered standout results, with revenue reaching nearly $12.8 billion, up 26.6% year over year. Energy gross profit hit a new quarterly record, driven by strong global demand and high deployments of MegaPack and Powerwall across all regions, as noted in a report from The Motley Fool.
Tesla also stated that paid Full Self-Driving customers have climbed to nearly 1.1 million worldwide, with about 70% having purchased FSD outright. The company has now fully transitioned FSD to a subscription-based sales model, which should create a short-term margin headwind for automotive results.
Free cash flow totaled $1.4 billion for the quarter. Operating expenses rose by $500 million sequentially as well.
Production shifts, robotics, and AI investment
Musk further confirmed that Model S and Model X production is expected to wind down next quarter, and plans are underway to convert Fremont’s S/X line into an Optimus robot factory with a capacity of one million units.
Tesla’s Robotaxi fleet has surpassed 500 vehicles, operating across the Bay Area and Austin, with Musk noting a rapid monthly expansion pace. He also reiterated that CyberCab production is expected to begin in April, following a slow initial S-curve ramp before scaling beyond other vehicle programs.
Looking ahead, Tesla expects its capital expenditures to exceed $20 billion next year, thanks to the company’s operations across its six factories, the expansion of its fleet expansion, and the ramp of its AI compute. Additional investments in AI chips, compute infrastructure, and future in-house semiconductor manufacturing were discussed but are not included in the company’s current CapEx guidance.
More importantly, Tesla ended the year with a larger backlog than in recent years. This is supported by record deliveries in smaller international markets and stronger demand across APAC and EMEA. Energy backlog remains strong globally as well, though Tesla cautioned that margin pressure could emerge from competition, policy uncertainty, and tariffs.
Tesla is bringing closure to its flagship Model S and Model X vehicles, which CEO Elon Musk said several years ago were only produced for “sentimental reasons.”
The Model S and Model X have been light contributors to Tesla’s delivery growth over the past few years, commonly contributing only a few percentage points toward the over 1.7 million cars the company has handed over to customers annually since 2022.
However, the Model S and Model X have remained in production because of their high-end performance and flagship status; they are truly two vehicles that are premium offerings and do not hold major weight toward Tesla’s future goals.
On Wednesday, during the Q4 2025 Earnings Call, Musk confirmed that Tesla would bring closure to the two models, ending their production and making way for the manufacturing efforts of the Optimus robot:
“It is time to bring the Model S and Model X programs to an end with an honorable discharge. It is time to bring the S/X programs to an end. It’s part of our overall shift to an autonomous future.”
Musk said the production lines that Tesla has for the Model S and Model X at the Fremont Factory in Northern California will be transitioned to Optimus production lines that will produce one million units per year.
Tesla Fremont Factory celebrates 15 years of electric vehicle production
Tesla will continue to service Model S and Model X vehicles, but it will officially stop deliveries of the cars in Q2, as inventory will be liquidated. When they’re gone, they’re gone.
BREAKING: Tesla will wind down Model S and Model X production next quarter, Elon Musk confirms.
“It is time to bring the Model S and Model X programs to an end with an honorable discharge.” pic.twitter.com/Czn7aQjJE1
— TESLARATI (@Teslarati) January 28, 2026
Tesla has been making moves to sunset the two vehicles for the better part of one year. Last July, it stopped taking any custom orders for vehicles in Europe, essentially pushing the idea that the program was coming to a close soon.
Musk said back in 2019:
“I mean, they’re very expensive, made in low volume. To be totally frank, we’re continuing to make them more for sentimental reasons than anything else. They’re really of minor importance to the future.”
That point is more relevant than ever as Tesla is ending the production of the cars to make way for Optimus, which will likely be Tesla’s biggest product in the coming years.
Musk added during the Earnings Call on Wednesday that he believes Optimus will be a major needle-mover of the United States’ GDP, as it will increase productivity and enable universal high income for humans.
Tesla confirms Robotaxi expansion plans with new cities and aggressive timeline
Tesla (TSLA) Q4 and FY 2025 earnings call: The most important points
