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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.
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Tesla China’s domestic sales fell 4.8% in 2025, but it’s not doom and gloom
Despite the full-year dip, Tesla finished the year with record domestic sales in December.
Tesla posted 625,698 retail vehicle sales in China in 2025, marking a 4.8% year-on-year decline as the EV maker navigated an increasingly competitive EV market and a major production transition for its best-selling vehicle.
Despite the full-year dip, Tesla finished the year with record domestic sales in December.
Retail sales slip amid Model Y transition
Tesla’s 2025 retail sales in China were down from 657,102 units in 2024, when the company ranked third in the country’s new energy vehicle (NEV) market with a 6.0% share. In 2025, Tesla’s share slipped to 4.9%, placing it fifth overall, as noted in a CNEV Post report.
Part of the decline seemed tied to operational disruptions early in the year. Tesla implemented a changeover to the new Tesla Model Y in the first quarter of 2025, which required temporary production pauses at Giga Shanghai. That downtime reduced vehicle availability early during the year, weighing on the company’s retail volumes in China and in areas supplied by Giga Shanghai’s exports.
China remained one of Tesla’s largest markets, accounting for 38.24% of its global deliveries of 1.64 million vehicles in 2025. However, the company also saw exports from Giga Shanghai fall to 226,034 units, down nearly 13% year-on-year. It remains to be seen how much of this could be attributed to the Model Y changeover and how much could be attributed to other factors.
Strong December 2025 finish
While the full-year picture showed some contraction, Tesla closed 2025 on a high note. According to data from the China Passenger Car Association (CPCA), Tesla China delivered a record 93,843 vehicles domestically in China in December, its highest monthly total ever. That figure was up 13.2% from a year earlier and 28.3% higher than November.
The surge was driven in part by Tesla prioritizing domestic deliveries late in the year, allowing buyers to lock in favorable purchase tax policies. In December alone, Tesla captured 7.0% of China’s NEV market and a notable 12.0% share of the country’s battery-electric segment.
On a wholesale basis, Tesla China sold 851,732 vehicles in 2025, down 7.1% year-on-year. From this number, 97,171 were from December 2025 alone. Tesla Model 3 wholesale figures reached 312,738 units, a year-over-year decrease of 13.12%. The Tesla Model Y’s wholesale figures for 2025 were 538,994 units, down 3.18% year-over-year.
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Tesla Robovan’s likely first real-world use teased by Boring Company President
As per the executive, the vehicle will be used to move large crowds through Las Vegas during major events.
The Boring Company President Steve Davis has shared the most likely first real-world use for Tesla’s Robovan.
As per the executive, the vehicle will be used to move large crowds through Las Vegas during major events.
Tesla Robovan for high-demand events
During a feature with the Las Vegas Review-Journal, Boring Company President Steve Davis stated that the Tesla Robovan will be used in Sin City once the Vegas Loop expands across the Strip and downtown and the fleet grows to about 1,200 Teslas.
At that scale, Robovans would primarily be deployed during predictable surges, such as game days and large shows, when many riders are traveling to the same destination at the same time.
“The second you have four (passengers) and you have to start stopping, the best thing you can do is put your smallest vehicle in, which is a car. But if you know people are going to the stadium because of a game, you’ll know an hour before, two hours before, that a lot of people are going to a game or a Sphere show, if you are smart about it, that’s when you put a high occupancy vehicle in, that’s when you put the Robovan in,” Davis said.
Vegas Loop expansion
Steve Davis’s Robovan comment comes amid The Boring Company’s efforts to expand the Vegas Loop’s airport service. Phase 1 of rides to Harry Reid International Airport began last month, allowing passengers to travel from existing Loop stations such as Resorts World, Encore, Westgate, and the Las Vegas Convention Center.
Phase 2 will add a 2.2-mile dual-direction tunnel from Westgate to Paradise Road. That section is expected to open within months and will allow speeds of up to 60 mph on parts of the route, while expanding the fleet to around 160 vehicles.
Future phases are expected to extend tunnels closer to airport terminals and add multiple stations along University Center Drive. At this point, the system’s fleet is expected to grow close to 300 Teslas. The final phase, an underground airport station, was described by Davis as the system’s “holy grail.” This, however, has no definite timeframe as of yet.
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Tesla seeks engineer to make its iOS Robotaxi app feel “magical”
It appears that Tesla is hard at work in ensuring that users of its Robotaxi service are provided with the best user experience possible.
Tesla is hiring an iOS Engineer for its Robotaxi app team, with the job posting emphasizing the creation of polished experiences that make the service not just functional, but “magical.”
Needless to say, it appears that Tesla is hard at work in ensuring that users of its Robotaxi service are provided with the best user experience possible.
Robotaxi App features
As observed by Tesla community members, Tesla has gone live with a job listing for an iOS Engineer for its Robotaxi App. The job listing mentions the development of a “core mobile experience that enables customers to summon, track, and interact with a driverless vehicle. From requesting a ride to enabling frictionless entry, from trip planning to real-time vehicle status and media control.”
Interestingly enough, the job listing also mentioned the creation of polished experiences that make the Robotaxi more than just functional. “You will take full ownership of features—from architecture design to robust implementation—delivering delightful and polished experiences that make Robotaxi not just functional, but magical,” Tesla noted in its job listing.
Apple’s “magical” marketing
Tesla’s use of the word “magical” when referring to the Robotaxi app mirrors the marketing used by Apple for some of its key products. Apple typically uses the word when referring to products or solutions that transform complex technology into something that feels effortless, simple, and natural to daily life. Products such as the AirPods’ seamless pairing with the iPhone and FaceID’s complex yet simple-to-use security system have received Apple’s “magical” branding.
With this in mind, Tesla seems intent on developing a Robotaxi app that is sophisticated, but still very easy to use. Tesla already has extensive experience in this area, with the Tesla App consistently being hailed by users as one of the best in its segment. If Tesla succeeds in making the Robotaxi app worthy of its “magical” branding, then it wouldn’t be a surprise if the service sees rapid adoption even among mainstream consumers.
Tesla China’s domestic sales fell 4.8% in 2025, but it’s not doom and gloom
Tesla Robovan’s likely first real-world use teased by Boring Company President
