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

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9 years ago

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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:

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“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.

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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.

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Tesla aiming to produce first “legion” of Optimus robots this 2025

Tesla is aiming to start the production of Optimus this year, and its first run will be no joke.

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5 hours ago

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March 21, 2025

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Credit: Tesla

Tesla’s Q1 2025 All-Hands meeting saw CEO Elon Musk share a key update about the company’s most ambitious product yet — Optimus. As per Musk, Tesla is aiming to start the production of Optimus this year, and its first run will be no joke. 

Tesla Optimus’ Quick Evolution

Tesla initially announced Optimus during its AI Day event in 2021. At the time, Tesla only had a mockup of the robot and a literal person in a suit to demonstrate what Optimus could look like. By 2022, Tesla had a working prototype of the robot. Optimus’ progress has been rapid since then, with several dozens of the humanoid robots interacting with attendees at the Cybercab’s unveiling last October.

Optimus’ Potential

During the recent All-Hands meeting, Elon Musk reiterated the idea that Optimus could very well be the biggest product of all time, likely being ten times larger than the next-biggest product. Musk also shared an update about Optimus’ production, stating that the first humanoid robot has been manufactured at the Fremont Factory.

A Legion for 2025

When discussing Optimus’ ramp, Musk clarified that Tesla is internally aiming for enough parts to produce 10,000 to 12,000 Optimus robots this year. However, since Optimus is a completely different product, even half of 10,000 units would be a huge victory for Tesla. Tesla also plans to ramp Optimus to a notable degree in 2026, with the company aiming for 50,000 units, or 10 “legions” of humanoid robots, next year.

“So this year, we hopefully will be able to make about 5,000 Optimus robots.  We’re technically aiming for enough parts to make 10,000, maybe 12,000, but since it’s a totally new product with a totally new, like everything is totally new, I’ll say we’re succeeding if we get to half go the 10,000.

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“But even 5,000 robots, that’s the size of a Roman legion, FYI, which is like a little scary thought. Like a whole legion of robots, I’ll be like ‘whoa.’ But I think we will literally build a legion, at least one legion of robots this year, and then probably 10 legions next year. I think it’s kind of a cool unit, you know? Units of legion. So probably 50,000-ish next year,” Musk said.

Tesla’s Q1 2025 All-Hands Meeting can be viewed below.

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Tesla Shanghai Megafactory starts exporting Megapacks, first to Australia

Tesla Asia celebrated the Shanghai Megafactory’s first Megapack exports on X.

Published

6 hours ago

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March 21, 2025

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Credit: Tesla Asia/X

Tesla has begun exporting Megapack battery systems from its Shanghai Megafactory, with the first shipment departing for Australia on Friday. This marks a key step in Tesla Energy’s expansion into the global energy storage industry, utilizing its new China-based Megafactory to supply several new markets.

Tesla Asia celebrated the Shanghai Megafactory’s first Megapack exports through its official social media account on X.

Tesla Megapacks in Focus

The Tesla Megapack is capable of storing 3.9 MWh of energy, and they are designed for grid use. As per Tesla in its official website, each Megapack battery has enough energy to power an average of 3,600 homes for one hour. The Megapack is designed to be infinitely scalable as well, making it a good fit for large-scale sustainable energy projects.

The Shanghai Megafactory

The Shanghai Megafactory began production in early 2025, a record eight months after its May 2024 groundbreaking. With an initial output of 10,000 units annually, equal to about 40 GWh, the Shanghai Megafactory has the potential to significantly boost Tesla’s battery storage deployments.

As per a report from Xinhua News Agency, Tesla is expecting its energy deployments to rise 50% year-over-year this 2025.

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Tesla Leaders on the Shanghai Megafactory

Mike Snyder, vice president of energy and charging at Tesla, previously outlined the potential of the Shanghai Megafactory. “Megafactory gives us the ability to scale production and efficiency. We can lower logistics costs as well as product costs, and grow the business to new markets,” he stated. 

The Shanghai Megafactory also seems to be part of Tesla’s efforts to grow its presence in China, which was highlighted by CEO Elon Musk during a meeting with Chinese Premier Li Qiang. During their meeting, Musk reportedly stated that “Tesla is willing to deepen cooperation with China and achieve more win-win results.”

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Shark Tank’s O’Leary roasts Tim Walz over Tesla stock hate session

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8 hours ago

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March 21, 2025

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Shark Tank personality and legendary investor Kevin O’Leary roasted former Vice Presidential nominee Tim Walz over his comments regarding Tesla shares earlier this week.

Walz, a Minnesota Democrat, said that he recently added Tesla (NASDAQ: TSLA) to his Apple Stocks app so he could watch shares fall as they have encountered plenty of resistance in 2025 so far. He said that anytime he needs a boost, he looks at Tesla shares, which are down 36 percent so far this year:

Walz, among many others, has been critical of Tesla and Elon Musk, especially as the CEO has helped eliminate excess government spending through the Department of Government Efficiency (DOGE).

However, Kevin O’Leary, a legendary investor, showed up on CNN after Walz’s comments to give him a bit of a reality check. O’Leary essentially called Walz out of touch for what he said about Tesla shares, especially considering Tesla made up a good portion of the Minnesota Retirement Fund.

As of June 2024, the pension fund held 1.6 million shares of Tesla stock worth over $319.6 million:

O’Leary continued to slam Walz for his comments:

“That poor guy didn’t check his portfolio and his own pension plan for the state. It’s beyond stupid what he did. What’s the matter with that guy? He doesn’t check the well-being of his own constituents.”

He even called Walz “a bozo” for what he said.

Of course, Walz’s comments are expected considering Musk’s support for the Trump Administration, as the Tesla CEO was a major contributor to the 45th President’s campaign for his second term.

However, it seems extremely out of touch that Walz made these comments without realizing the drop was potentially hurting his fund. While we don’t know if the fund has sold its entire Tesla holdings since June, as a newer, more recent report has not been released yet, it seems unlikely the automaker’s shares are not still making up some portion of the fund.

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