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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 exec hints at a wild fix for Robotaxi’s biggest weather problem
Tesla VP Lars Moravy says focused lasers could keep robotaxi cameras clear instead of wipers.
Tesla may one day use lasers instead of wiper blades to keep its robotaxi cameras clear. Lars Moravy, Tesla’s Vice President of Vehicle Engineering, floated the idea in a new episode of Jay Leno’s Garage released Monday, where he and design chief Franz von Holzhausen walked Leno through the Model Y L.
“If you fire them in a focused area, you can clean the sheet of water and create a barrier,” Moravy said. “When you think about autonomy, it might be a good solution to only clean the area where the camera is.” He added that clearing an entire windshield would take too many lasers to be practical.
🚨 Jay Leno has released a new episode breaking down the Model Y L. You can watch it here: https://t.co/umMp85UEaB — TESLARATI (@Teslarati) November 9, 2026
The comment brings back one of Tesla’s stranger patents. The company filed for “Pulsed Laser Cleaning of Debris Accumulated on Glass Articles in Vehicles and Photovoltaic Assemblies” in May 2019, and the U.S. Patent Office granted it in September 2021. An updated divisional version was granted on March 31, 2026. The system detects debris on the glass, identifies what it is, and pulses the laser at a calibrated rate so the beam never penetrates deeper than the glass itself. The filing names windshields, side windows, camera lenses and solar panels as possible targets.
Lasers were once rumored for the Cybertruck, which appeared at its November 2019 unveiling with no wipers at all. Tesla eventually settled on a single oversized blade, and Elon Musk admitted the wiper was the part of the truck that troubled him the most. That production line is now scheduled to shut down around mid 2027 to make room for more Cybercab output.
What has changed since then is who is in the vehicle. A privately owned car has a driver who can notice a smeared windshield and do something about it. A Cybercab heading to its next pickup has nobody on board to check. Tesla has been chipping away at that problem with conventional hardware. Model Y Robotaxis in Austin were spotted with washers on their side repeater cameras in January, and a lens cleaning patent granted in May describes a fluid and wiper assembly for vehicle cameras and Optimus’ eyes. A laser would remove the fluid and the blades, both of which need regular replacement across a fleet.
The same episode gave Leno his first ride on Full Self-Driving (Supervised). The Model Y L pulled over on its own when an ambulance approached with its sirens on. “We got it on self-driving mode! I’m not touching anything,” Leno said. Moravy and von Holzhausen also explained that owners remain responsible while using FSD (Supervised), while Tesla takes responsibility for Robotaxi rides because it acts as the operator. Tesla launched the Model Y L in the U.S. in July at $61,990.
Moravy gave no timeline, and he described the laser setup as something Tesla is considering rather than a confirmed feature. The fleet it would serve keeps getting bigger, though. Tesla launched unsupervised Robotaxi service in San Antonio on Monday, its eighth city, and expanded its Austin service area to roughly 443 square miles on the same day. Several of those markets, including Houston, Miami and Tampa, see heavy seasonal rain.
Tesla launched unsupervised Robotaxi service in San Antonio, Texas, on November 9, 2026, with the first rides beginning at 5 a.m. local time.
The company’s official Robotaxi account on X posted the announcement just after midnight, sharing a map that outlines a large operational zone covering much of the city. The geofence is roughly 274 to 275 square miles, making it Tesla’s largest day-one Robotaxi service area to date.
🚨 Tesla just announced that Robotaxi is available in San Antonio, TX
First rides at 5am local time! https://t.co/azck6NlD8H
— TESLARATI (@Teslarati) November 9, 2026
The zone centers on downtown, covers nearly everything inside Loop 410, and extends north to Loop 1604 between Interstate 10 and U.S. 281, with further reach west past State Highway 151, east beyond I-35, and south toward I-37. This area encompasses about one million residents and hundreds of thousands of jobs.
San Antonio International Airport lies inside the geofence, though Tesla is not currently offering airport pickups or drop-offs. This hopefully will happen soon, as ride-sharing to and from the airport can be expensive.
The launch makes San Antonio Tesla’s eighth unsupervised Robotaxi city and its fifth in Texas, joining Austin, Houston, Dallas, and Fort Worth. Florida markets in Miami, Orlando, and Tampa are also live.
🚨 Here’s every active geofence, by size (not including the Bay Area geofence):
• Austin: 435 sq mi (first ride Jun 22, 2025) · Cybercabs live, expanded today • San Antonio: ~275 sq mi (first ride Nov 9, 2026) • Houston: 254 sq mi (Apr 18, 2026) • Fort Worth: 143 sq mi (Nov 2, 2026) • Dallas: 81 sq mi (Apr 18, 2026) • Miami: 31 sq mi (Jul 3, 2026) • Orlando: 26 sq mi (Jul 21, 2026) • Tampa: 24 sq mi (Jul 21, 2026)
— TESLARATI (@Teslarati) November 9, 2026
Service uses modified Model Y vehicles operating without a safety driver in the vehicle, consistent with recent unsupervised expansions. Cybercab two-seaters remain limited primarily to Austin for now. It’s worth noting that Dept. of Transportation officials in Texas have already ok’d the Cybercab’s operation in Austin, and one official called it “a tangible example of how quickly our transportation system is evolving.”
San Antonio was previously listed among near-term targets in Tesla’s October 2026 Robotaxi safety materials, alongside Las Vegas, Phoenix, and Jacksonville. The rapid Texas rollout follows Fort Worth’s unsupervised debut on November 2 and builds on Austin’s original launch in June 2025.
The 274-square-mile debut remains substantially larger than Waymo’s local footprint and marks continued progress in Tesla’s unsupervised autonomy efforts after starting the year with no such rides. The company has stated ambitions for broader 24/7 operations by the end of 2026 as vehicle counts and software reliability improve.
Tesla has started to perform earthworks engineering on the roughly 3,000-acre site in Fort Bend County, Texas, advancing the massive $10 billion Project Crystal Sun plan to build a vertically integrated solar manufacturing complex.
Flyover drone footage from S.E. Robinson, Jr. released this morning shows the location under development. Tesla has crews on site performing large clearings, but you can also see equipment staging areas, the use of an existing homestead, and active leveling across a substantial portion of the property.
Tesla has started construction on Project Crystal Sun, its $10B vertically integrated solar factory near Houston, Texas.
The plant will make everything from silicon ingots and wafers to finished cells and panels, with operations targeted for Q1 2029.
@SERobinsonJr with a great flyover of the facility:
— TESLARATI (@Teslarati) November 9, 2026
Public filings first submitted in July under Texas’s Jobs, Energy, Technology and Innovation Act describe a plant that would manufacture the full solar chain: everything from silicon ingots, wafers, coated cells, and finished modules.
Tesla projects 9,712 permanent jobs by 2033, ramping from roughly 1,900 positions in the first year of operations, plus a peak of about 1,147 construction jobs. Construction is targeted for 2026–2028, with commercial production beginning in the first quarter of 2029. An accompanying economic analysis estimates the project could add roughly $107 billion to Texas GDP over several decades.
Local incentives have cleared major hurdles. Lamar Consolidated Independent School District unanimously approved school-tax limitations in September, and Fort Bend County commissioners approved a package of abatements and related agreements in late October that could extend equipment tax breaks for as long as 35 years.
Tesla had previously indicated it was evaluating a competing out-of-state location.
The effort fits broader statements by Musk that Tesla and SpaceX are each working toward 100 gigawatts of annual U.S. solar manufacturing capacity. If built as described, Project Crystal Sun would stand as one of the largest domestic attempts to create a fully integrated solar supply chain on American soil.
While Tesla has not issued a formal groundbreaking announcement, the visible site preparation and high-profile social media activity represent a concrete step forward for a project that has moved from confidential filings to active earthworks in a matter of months.
Tesla exec hints at a wild fix for Robotaxi’s biggest weather problem
Tesla Robotaxi enters its newest city, reaching San Antonio
