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

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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:

“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.

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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.

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We’ve also included a video tutorial on how to replace the Model S 12V battery.

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SpaceX readies Starship Flight 14 for a historic journey into uncharted territory

SpaceX finished Starship’s Flight 14 rehearsal, clearing the way for its first orbital flight Monday.

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Sunrise at Starbase. Starship is stacked for opportunistic full-stack testing ahead of Flight 14 via SpaceX
Sunrise at Starbase. Starship is stacked for opportunistic full-stack testing ahead of Flight 14 via SpaceX

SpaceX has cleared one of the last hurdles before Starship’s first trip to orbit. The company posted on X Thursday afternoon that its launch rehearsal for Flight 14 was complete, keeping the mission on track for Monday, September 28. The launch window opens at 7:15 a.m. CT at Starbase, Texas, and runs for 75 minutes.

A wet dress rehearsal is essentially launch day without the launch. Crews fill Booster 21 and Ship 41 with thousands of tons of extremely cold propellant, run the countdown nearly to ignition, then drain everything back out. It lets engineers catch leaks or equipment problems before anything leaves the pad. SpaceX still needs a launch license from the FAA before the stack, which stands 407 feet tall, can fly.

Flight 14 matters because of where it is going. All 13 previous Starship flights followed a suborbital path, which works like throwing a ball extremely high and far: the vehicle reaches space, but it is always on a course that brings it back down within about an hour. This time, Ship 41 will perform a short engine firing called an orbital insertion burn roughly 25 minutes after liftoff, giving it enough speed to keep falling around Earth instead of back into it. SpaceX plans about six laps at an altitude near 275 kilometers (171 miles) over nearly 10 hours, as Teslarati detailed when the mission was first announced.


Getting into orbit also means Starship has to prove it can get back out. The ship must relight a single Raptor engine in space to slow down for reentry. SpaceX says it will only attempt the orbital insertion burn after flight controllers confirm the hardware needed for that return burn has enough backup, and its flight plan includes health checks that could shorten the mission to two or five orbits.

Flight 14 is also the first to put working satellites into service. Flight 13 carried 20 Starlink V3 satellites in July, but they came back down with the ship because that mission never reached orbit. This time, 26 V3 satellites are meant to stay up and join the constellation within a few weeks. Together they add about 26 terabits per second of network capacity, which SpaceX says is roughly 10 times what a single Falcon 9 launch of older V2 Mini satellites adds. Three of them carry cameras that will photograph Starship’s heat shield in orbit to check for tile damage before reentry.

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The hardware has changed too. Ship 41 flies with extra fasteners on tiles in the most vulnerable areas, fixes for gaps where superheated plasma slipped behind tiles, and curved tiles designed to reduce heating between them. Two tiles recovered from Ship 40 will fly again, the first reuse of any part of a Starship heat shield. Booster 21 carries better engine filtering and new relight software after ice clogged three center engines on the previous booster, leaving only eight of 13 engines to restart for its landing burn.

Ship 41 is targeting a splashdown in the Pacific Ocean west of Chile, a new recovery zone after several Indian Ocean landings, while Booster 21 aims for the Gulf. Neither will be caught by the tower on this flight. Elon Musk said in August that a ship catch was likely “in a few months.”

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Google just picked SpaceX for its first step into orbital AI

Google will launch its first Project Suncatcher AI satellite on SpaceX’s Transporter-18 rideshare next week.

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Google is about to put its own AI chips into orbit for the first time, and it is paying SpaceX to get them there.

The company said Thursday that the first in-orbit test of Project Suncatcher, its research effort to find out whether space can host large-scale AI computing, will fly next week on SpaceX’s Transporter-18 rideshare mission.

The satellite, called MVP, is about the size of a refrigerator and carries four of Google’s Tensor Processing Units, the same chips Google runs in its ground data centers. Google originally planned to launch two custom satellites in 2027, but chose to move faster by integrating its chips into a satellite.

MVP’s solar panels supply about one kilowatt of power, and Google will run Gemini models on the TPUs only in bursts of roughly 15 minutes before the chips shut down so the radiators can shed heat. In a blog post, Google said its Trillium TPUs survived vibration testing that mimicked sustained launch loads of up to 10g, with individual components seeing 50 to 100g, and handled a radiation dose greater than a five year mission would deliver.

SpaceX and Google mull massive partnership on Musk’s orbital data dream: report

Next week’s flight, slated for October 1, follows a relationship that became public in May, when Teslarati reported that Google was in talks with SpaceX for a launch deal tied to orbital data centers. Google also holds a stake of roughly 6% in SpaceX.

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The two companies are chasing the same idea from very different starting points. SpaceX’s own orbital compute program is built around the AI1 satellite, a roughly 70 meter structure derived from Starlink V3 hardware that is designed for 150 kW of peak compute, about 150 times the power MVP will draw. Elon Musk has brushed off concerns about crowding orbit with those satellites, and SpaceX is building its Gigasat factory in Bastrop, Texas, to produce them, targeting an annualized rate of about 1 GW of space compute by the end of 2027.

Musk also posted on X on Thursday that “the amount of compute in space will obviously round up to 100% of all compute.”

Google has been more cautious in public. Its research estimates that launch prices need to fall below about $200 per kilogram before an orbital data center can compete with a ground facility on energy cost, a threshold the company believes could be reached around the mid 2030s. The Suncatcher team has said it expects the effort to remain a project rather than a product for years, which leaves the first real test of its hardware riding on a rocket from the company with the most aggressive timeline in the field.

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Tesla Cybercab gets initial tie-in to localized, in-house cathode plant

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Credit: Tesla

Tesla has taken another concrete step toward owning its battery supply chain, and it’s doing so with what is perhaps the most important vehicle in its short-but-storied history.

On September 23, Tesla announced that it has officially built the first Cybercab with cathode material produced in-house at the company’s first cathode plant in the U.S., and the first in the U.S. overall.

Active cathode material is the most expensive piece of a lithium-ion battery cell, and it often accounts for more than a third of cell cost. For years, the industry sourced a majority of it from Asia, but Tesla’s decision to make it in the United States bodes well for the Cybercab project. This is the latest chapter in Tesla’s vertical integration strategy, which began in public at Battery Day in 2020.

At the Battery Day Event, Elon Musk said the company would build a North American cathode plant and overhaul the process to cut costs and waste, while also making some of the most powerful and long-lasting cells in the industry.

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The Austin facility took years to appear. Tesla filed permits for “Project Cathode” in 2022 on land near Giga Texas. By mid-2022, the building frame was up and Tesla later invested hundreds of millions of dollars as part of a larger expansion of the Giga Texas plant. The company stated it was operating the first large-scale cathode production facility in North America to supplement 4680 cell production.

One month later, that material reached a finished Cybercab.

The timing of this breakthrough is monumental for the Cybercab program. As Tesla officially launched the first Cybercab rides to the public earlier this month, production of the ride-hailing-geared vehicle is moving forward on the planned S-curve that CEO Elon Musk told everyone to expect.

Nevertheless, packs of Cybercab units have been spotted throughout the United States, in an effort to potentially activate the fleet as soon as the company gains regulatory approval in various geographic areas.

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On top of that, Tesla owning the cathode step and pairing it with its own in-house lithium from the Gulf Coast refinery shortens the supply chain that once stretched thousands of miles and subjects every pack to fewer external price shocks and geopolitical risks.

Tesla is not yet independent of all of its foreign suppliers, as some precursor metals come from mines and chemical plants. But the first in-house cathode Cybercab shows the company is closing the most expensive and most concentrated gap in its battery production efforts. For a vehicle like Cybercab to operate at a high utilization within the Robotaxi network, that control over cost is so crucial.

It is arguably as important as the software that drives it.

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