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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:

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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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Elon Musk: Tesla autonomous driving might spread faster than any tech

The CEO noted that “hardware foundations have been laid for such a long time.”

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Credit: Tesla

Elon Musk has shared one of his most optimistic forecasts for Tesla’s self-driving rollout yet. As per the CEO, Tesla’s self-driving system could see the fastest technological adoption in history, thanks to the fleet’s capability to gain autonomous capabilities through a software update.

The CEO shared his forecast in a post on social media platform X.

Tesla’s aims to scale autonomy

Musk’s comment came as a response to industry watcher Sawyer Merritt, who posted a comparison between the geofence of Tesla’s Robotaxi network and Waymo’s service area. As can be seen in the graphic, Tesla’s Austin geofence has gotten noticeably larger compared to Waymo’s service area. 

In his response, Musk stated that “Tesla autonomous driving might spread faster than any technology ever.” He also stated that “hardware foundations have been laid for such a long time,” as a software update could unlock full autonomy “for millions of pre-existing cars in a short period of time.”

Musk’s comment bodes well for Tesla’s Robotaxi ambitions, which seem to be finally in reach with the deployment of Unsupervised FSD in vehicle factories, as well as Austin and the Bay Area. For now, however, Tesla’s Austin Robotaxis and Bay Area ride-hailing vehicles are still operated with a safety monitor in the driver’s seat. 

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Tesla’s latest Austin expansion

Tesla recently expanded its Austin Robotaxi service area this week to 243 square miles, its largest yet and nearly triple the coverage from two months ago. The move outpaces Waymo’s local service footprint, which remains at around 90 square miles.

The expansion marks Tesla’s second major Austin update since August and emphasizes its push to dominate the autonomous ride-hailing landscape. With both Tesla and Waymo racing to prove scale and reliability, Musk’s confidence suggests the real contest may be about who can move fastest once the tech flips on across Tesla’s fleet. Once that happens, Tesla would effectively be able to win the self-driving race. 

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Tesla sends clear message to Waymo with latest Austin Robotaxi move

It is the first expansion Tesla has made in Austin since the one on August 26. The company still operates in the Bay Area of California as well, referring to that program specifically as a “ride-hailing service.”

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Credit: Tesla

Tesla has sent a clear message to Waymo with its latest move to its Robotaxi program in Austin, Texas.

Tesla and Waymo are the two true leaders in autonomous ride-hailing to an extent. Tesla has what many believe is a lot of potential due to its prowess with the Supervised Full Self-Driving suite. It is also operating a driverless Robotaxi service in Austin with a “Safety Monitor” that sits in the passenger’s seat.

Tesla explains why Robotaxis now have safety monitors in the driver’s seat

The two companies have been competing heavily in the market since they both launched driverless ride-hailing services in Austin this year: Waymo’s in March and Tesla’s in June.

One of the main drivers in the competition between the two is service area size, or the geofence in which the cars will operate without a driver. In August, the two were tied with a service area of about 90 square miles (233.099 sq. km).

Tesla then expanded to about 170 square miles (440.298 sq. km) on August 26, dwarfing Waymo’s service area and expanding to freeways. Tesla’s freeway operation of the Robotaxi suite requires the Safety Monitor to be in the driver’s seat for safety reasons.

On Tuesday evening, Tesla made another move that sent a clear message to Waymo, as it expanded once again, this time to 243 square miles (629.367 sq. km).

This is according to Robotracker:

It is the first expansion Tesla has made in Austin since the one on August 26. The company still operates in the Bay Area of California as well, referring to that program specifically as a “ride-hailing service.”

Yesterday, it expanded that service to the San Jose Mineta International Airport, something it has been working on for several months.

Waymo has its own set of distinct advantages over Tesla as well, as it operates in more cities and states than the EV maker. Waymo currently has its autonomous vehicle services in Phoenix, Arizona, San Francisco, Los Angeles, Austin, and Atlanta, Georgia.

Tesla plans to have half of the U.S. population with access to the Robotaxi platform by the end of the year.

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Tesla exec reveals shock development with Cybercab

“If we have to have a steering wheel, it can have a steering wheel and pedals.”

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(Credit: Teslarati)

Tesla is planning to launch the Cybercab in the second quarter of next year, and it is designed to be fully autonomous, so much so that the company is planning to build it without a steering wheel or pedals.

However, a Tesla executive said today that the company could ditch that idea altogether in what would be a major shift from the plans the company, and especially its CEO Elon Musk, have announced for the Cybercab.

Earlier today, Robyn Denholm, the company’s Chair for the Board of Directors, revealed that Tesla would potentially switch up its plans for the Cybercab based on potential regulatory requirements.

Credit: Tesla Europe & Middle East | X

Currently, even autonomous vehicles that operate for companies like Tesla and Waymo are required to have steering wheels and pedals. From a regulatory perspective, this could halt the plans Tesla has for Cybercab.

Denholm said in an interview with Bloomberg:

“If we have to have a steering wheel, it can have a steering wheel and pedals.”

Interestingly, Musk and Tesla have not veered away from the idea that the vehicle will be without these operational must-haves.

Since the vehicle was revealed last October at the We, Robot event in Los Angeles, Tesla has maintained that the car would be built without a steering wheel or pedals, and would equip two seats, which is what is statistically most popular in ride-sharing, as the vast majority of rides have only one or two passengers.

Musk doubled down on the plans for Cybercab as recently as last week, when he said:

“That’s really a vehicle that’s optimized for full autonomy. It, in fact, does not have a steering wheel or pedals and is really an enduring optimization on minimizing cost per mile for fully considered cost per mile of operation. For our other vehicles, they still have a little bit of the horse carriage thing going on where, obviously, if you’ve got steering wheels and pedals and you’re designing a car that people might want to go very direct past acceleration and tight cornering, like high-performance cars, then you’re going to design a different car than one that is optimized for a comfortable ride and doesn’t expect to go past sort of 85 or 90 miles an hour.”

Cybercab is fully conceptualized as a vehicle that has zero need for pedals or a steering wheel because it is aimed toward being fully reliant on a Level 5 autonomous platform.

Tesla is ramping its hiring for Cybercab vehicle manufacturing roles

Regulators could get in the way of this, however, and although the car could drive itself and be a great solution for ride-hailing, it might need to have these controls to hit the road in the future.

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