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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.
The Tesla Model Y L is arguably the most hyped trim of the all-electric crossover, other than the Performance configuration that comes with white-knuckle speed and sports car-level handling.
However, it is not all perfect. Tesla owners in China who took delivery of the Model Y L, denoted with an L to highlight its longer wheelbase, are experiencing what they are referring to as “collapsing” of the rear wheels, as suspension issues appear to be an issue with some of the builds.
🚨 Model Y L owners in China report rear suspension sag
• Six-seat long-wheelbase Y. Shanghai. On sale since August 2025
• Owners say the rear tire-to-arch gap shrinks after mileage or a full load. Some cases after about 9,000 km loaded. Others near 30,000 km
• Tesla service… pic.twitter.com/Lr6i5Tbi07— Joe Hansen (@joehansen) September 1, 2026
The gap between the wheel arch and tire has narrowed to the point that “not even a single finger” could fit, according to a report from Car News China. The failures are not tied to a specific mileage, as one owner said that after just 9,000 kilometers (5,600 miles), they noticed the suspension issue when their car was fully loaded.
Another one had the issue at 30,000 kilometers (18,640 miles) and noticed that the wheel gap shrank to two fingers, so not as drastic as the person who reported a similar issue at 9,000 km.
Tesla Model Y L is gaining momentum in China’s premium segment
Along with the visual recognition of the issue, others are saying the sagging is causing abnormal wear on the inside of the tires. Extra weight and instant torque already provide additional stress on the tires in electric vehicles during normal operation, so it is no surprise that this is another complaint.
There has been no recall issued by Tesla, and the company has not yet publicly acknowledged the issue.
Some are suggesting that owners use a “finger test” to self-diagnose whether there is an issue with the suspension. There should be four fingers between the tire and the wheel well; anything less than that starts to get dicey.
Tesla is starting to truly tease and hype its groundbreaking Cybercab event, which takes place tomorrow in Austin, Texas. It will be the first time members of the public will be able to ride in a Cybercab, a vehicle without any manual controls, on public roads.
Tesla has been dropping some hype on X over the past several days, but this morning, the excitement has truly started to build up for the event. Although Cybercab has been unveiled before, this is truly Tesla’s announcement that it is ready to start offering autonomous rides for public passengers in its new ride-hailing-geared vehicle for the first time.
The hype has started with a variety of different social media posts that are a true indication that Tesla is preparing for something big. Teasing so much of the potential of Cybercab, including its ability to truly revolutionize how people hail rides for local travel, is what the big idea for the event entails. The time that many Tesla owners, fans, and investors have been waiting for is potentially here:
— Tesla (@Tesla) September 2, 2026
The event has remained slim on details. Even invitees are still awaiting true details about what the event will entail, where they’ll go, and what is in store for the evening. This is pretty typical for an event run by Tesla; they keep things under wraps for the most part until the very last minute.
However, there is no secret about what the real intention of Tesla is for this event: it is going to be a huge reveal party for a vehicle that has no steering wheel and no pedals. It is a truly massive step for the company moving forward.
No steering wheel, no pedals
— Tesla Robotaxi (@robotaxi) September 2, 2026
Speculation persists as to whether this is going to be an event that simply announces that rides will begin with the Cybercab, or it will be something more substantial. Tesla has said in the past that they plan to sell the Cybercab to the general public in what could become a great way to earn passive income by adding it to a more global fleet of Robotaxi-geared vehicles.
Tomorrow, the show begins in Austin, and the Cybercab goes live at some capacity; we just don’t know exactly how quite yet.
News
SpaceX tells the FCC that Starship Flight 14 is going to orbit
SpaceX filed with the FCC for Starship Flight 14, its first true orbital launch attempt.
SpaceX has asked the Federal Communications Commission for permission to fly Starlink terminals during Starship’s fourteenth flight test, and the filing lays out a genuine trip to orbit, something the program has never attempted.
Every Starship flight so far, including Flight 13’s successful splashdown in the Indian Ocean on July 24, has flown a suborbital arc that ends with the ship reentering the atmosphere within the same hour it launches. The FCC paperwork describes a mission profile built around an actual orbital insertion instead.
The payload is the other half of the story. Flight 13 carried 20 production Starlink V3 satellites, but because that mission never reached orbit, the satellites reentered along with the ship rather than joining the constellation, something Teslarati covered in detail after SpaceX released footage shot from one of those satellites as it drifted away from Starship in space. Flight 14 is designed to close that gap. If the orbital insertion holds, the roughly 20 V3 satellites onboard would separate into an operational orbit and could eventually go into service, each one rated for about 1 terabit per second of downlink capacity by SpaceX’s own account.
SpaceX announces new Starbase for ‘thousands of Starship launches annually’
Elon Musk first flagged the orbital attempt during SpaceX’s August 4 earnings call, the company’s first as a public entity following its June IPO under the ticker SPCX. He also floated catching the ship with the Starbase tower on the same flight, an idea he walked back on August 20, saying the catch attempt would more likely come “in a few months,” as Teslarati reported at the time. Flight 14 will instead target a splashdown for the ship in the Indian Ocean, the same recovery method used since Flight 12.
Hardware has been catching up to the ambition. Booster 21 completed a full 33-engine static fire on August 28, and Ship 41 finished its own six-engine test the week before. An airspace briefing circulated to pilots on August 20 listed September 15 as the target date, later than the end of August window Musk mentioned on the earnings call, though SpaceX has not confirmed a launch date publicly and Starship schedules routinely slip while hardware and FAA paperwork line up.
The FCC filing itself does not guarantee a launch date. It covers communications authority, and not flight readiness, considering SpaceX still needs Ship 41 fully stacked and cleared by the FAA before Flight 14 can fly. But the filing is a real marker of intent and it puts a specific regulatory process behind what had so far only been Musk’s word on the earnings call.
Tesla Model Y L gets suspension complaints in over odd issue China
Tesla Cybercab event gains steam ahead of massive launch
