Unveiling the Tesla Semi's Battery Specs: A Complete Guide to the 822 kWh and 548 kWh Packs

Overview

In April 2025, the California Air Resources Board (CARB) released Executive Order A-374-0095, officially confirming the battery capacities of the Tesla Semi. This regulatory filing ended years of speculation, revealing that the Long Range variant carries a 822 kWh usable battery pack while the Standard Range version uses a 548 kWh pack. Both packs rely on NCMA lithium-ion chemistry and are built with Tesla’s 4680 battery cells. This guide walks you through the significance of these numbers, how to interpret the data, and what it means for fleet operators and EV enthusiasts.

Prerequisites

Before diving into the details, you should have a basic understanding of:

• Electric vehicle battery terminology (e.g., kWh, usable vs. total capacity)
• The role of regulatory bodies like CARB in certifying vehicle compliance
• Lithium-ion battery chemistries (particularly NCMA – Nickel, Cobalt, Manganese, Aluminum)
• Tesla’s 4680 cell format

No prior knowledge of the Tesla Semi is required, but familiarity with heavy-duty electric trucks helps.

Step-by-Step Guide to Understanding the Tesla Semi's Battery Specs

1. Locate the Official Regulatory Filing

The primary source is CARB Executive Order A-374-0095, signed on April 15, 2025. This document is publicly available on CARB’s website. Look for the section labeled “Battery and Drivetrain” – it lists the usable energy capacities exactly as 822 kWh and 548 kWh. Tesla also confirms the cell chemistry: NCMA (Nickel-Cobalt-Manganese-Aluminum) with 4680 cells.

2. Understand the Battery Sizes in Context

Elon Musk originally claimed at the 2022 Semi delivery event that the long-range version would use a “roughly 900 kWh” pack. The CARB filing shows it’s actually 822 kWh – about 8.7% smaller. The Standard Range at 548 kWh is also lower than some earlier estimates. Why the discrepancy? Tesla likely optimized for weight, cost, and thermal management while still meeting range targets.

Key takeaway: 822 kWh and 548 kWh are usable capacities (the energy the driver can actually use). Total installed capacity is slightly higher due to buffer.

3. Compare Chemistry and Cell Technology

The NCMA chemistry used in these packs offers high energy density and improved longevity over older NCA or NMC chemistries. The addition of aluminum stabilizes the cathode, reducing degradation. The 4680 (46 mm diameter, 80 mm height) cylindrical cells provide structural benefits and enable Tesla’s tabless design for lower internal resistance and faster charging.

4. Interpret the Numbers for Practical Use

For fleet operators:

• Long Range (822 kWh): Targeted at 500 miles of range under ideal conditions. Given the battery capacity, expect real-world consumption around 1.6 kWh per mile (typical for a Class 8 truck).
• Standard Range (548 kWh): Likely delivers around 300-350 miles, suitable for shorter regional routes.

Both packs support Mega Charging (over 1 MW) to recharge in under 2 hours.

5. Verify with Cross-References

Check the CARB filing for additional parameters: voltage, continuous power output, and thermal limits. Cross-reference with Tesla’s own website or EPA filings once available. The numbers here are legally binding for certification, so they are definitive.

Common Mistakes

1. Confusing usable vs. total capacity: The CARB numbers are usable (state of charge window). Total pack capacity could be 860-870 kWh for the Long Range.
2. Assuming 822 kWh means 822 kW output: kWh is energy; kW is power. The Semi’s continuous power ratings are separate.
3. Overlooking NCMA chemistry specifics: This isn’t just “lithium-ion” – it’s a specific blend that affects charging curves and lifetime.
4. Mistaking CARB for EPA: CARB certifies compliance with California emissions rules, but the same numbers will likely appear in EPA applications.
5. Ignoring the 4680 cell’s impact: These cells are larger and structurally integrated, so actual module numbers differ from earlier 2170-based packs.

Summary

The Tesla Semi’s battery capacities are now officially confirmed as 822 kWh (Long Range) and 548 kWh (Standard Range), both utilizing NCMA chemistry with 4680 cells. These figures are slightly lower than earlier claims but represent final regulatory data. Understanding these specs helps in planning routes, charging infrastructure, and total cost of ownership. Always rely on official filings like CARB Executive Orders for definitive numbers.

Now that you’ve mastered the battery specs, explore how Tesla’s Mega Charger network and the Semi’s aerodynamic design maximize efficiency from these packs.