It should perform tremendously better than the standard lead-acid one.

The refreshed Tesla Model S and Model X include a huge number of new technologies, features and solutions. One of them is the all-new lithium-ion 12V auxiliary battery, which replaces a conventional lead-acid battery.

DragTimes happens to be probably the first to point out this new 12V battery in a Model S during the Plaid delivery event yesterday (see video from 26:29).

This new version appears to be very small and much lighter than a standard 12V battery. We strongly believe it will also perform tremendously better than the standard lead-acid one, which in many cases (and many models) died far too frequently.

Tesla Model S Plaid lithium-ion 12V auxiliary battery (source: DragTimes)
Tesla Model S Plaid lithium-ion 12V auxiliary battery (source: DragTimes)
Tesla Model S Plaid
Tesla Model S Plaid

A 12V lithium battery has tons of advantages in EVs as it saves space, weight, has a higher cycle life and calendar life and suits the application better. Lead-acid batteries are good for starting an engine with high current, which is completely not needed in EVs.

We guess that it will withstand much longer without a charge from the main battery through the DC/DC converter.

According to the owner's manual, the battery is 6.9 Ah and 15.5 V nominal, which translates to 106.95 Wh. That's not a particularly high value (an example Liontron battery 12.8 V / 20 Ah nominal is about 256 Wh) so we will wait for confirmation, but maybe Tesla figured out that it's enough. The smaller its capacity, the less expensive and more efficient (weight) the car is.

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The main traction battery (obviously lithium-ion) has a 450V nominal voltage and according to Tesla can operate at temperatures between -30°C up to 65°C, although not for a prolonged time.

12V auxiliary battery info from Model S Owner's manual

And here is quick info from the manual if you encounter a 12V battery issue (enlarge the image here):

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Tesla Model S Plaid specs

  • 390 miles (628 km) of EPA est. range
  • battery capacity: N/A
    450V battery system (nominal)
  • 0-60 mph (96.5 km/h) in 1.99 seconds (*with rollout subtracted)
  • 1/4 Mile 9.23@155 mph trap speed
  • top speed of 200 mph (322 km) †when equipped with the proper wheels and tires (available fall 2021)
  • three-motor all-wheel drive (one motor in the front and two motors in the rear)
  • system output: 1,020 hp (about 760 kW)
  • DC fast charging: at up to 250 kW (Superchargers)
    can replenish 187 miles (301 km) in 15 minutes
  • Drag Coefficient 0.208 Cd
  • Wheels 19" or 21"
  • Cargo 28 cu ft
  • Weight 4,766 lbs (2,162 kg)
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