Tesla has released a video demonstrating its Semi electric truck charging at a peak of 1.2 megawatts, highlighting the high-speed capabilities needed for long-haul trucking. The footage aligns with the truck's target of regaining 70% of its 500-mile range in 30 minutes. Separately, a redesigned version of the Semi was spotted, featuring efficiency improvements and design updates.
On December 31, 2025, Tesla's official Semi account on X shared a video of the electric truck undergoing a charging session monitored by engineers. The power output reached a peak of 1.2 MW (1,206 kW), consistent with the capabilities of Tesla's new V4 Cabinet architecture, which supports up to 1.2 MW for the Semi and 500 kW for vehicles like the Cybertruck.
The video provides a clear view of the Megacharger in action, though it lacks details on the truck's state-of-charge during the peak. Tesla has targeted the Semi to charge 70% of its range in 30 minutes, for a vehicle with a 500-mile range and an estimated 800-900 kWh battery pack. Based on the touted 1.7 kWh/mile efficiency, the pack is around 850 kWh, allowing approximately 20 kWh added per minute at 1.2 MW. This could theoretically enable a 10-80% charge in under 45 minutes, assuming the rate sustains without significant tapering due to heat.
The liquid-cooled cable and immersion-cooled connector appear effective in managing the high power, potentially aligning with the Megawatt Charging System or Tesla's proprietary solution.
In related developments, a redesigned Tesla Semi was spotted for the first time on the same day. It features a Model Y-style light bar, 15% improved efficiency at 1.7 kWh/mile, increased payload capability, design for autonomy, 500-mile range, 1.2 MW peak charging, and 800 kW drive power. Other changes include side windows that do not extend as far back, silver anti-slip diamond traction strips on steps, and various under-the-skin improvements.
Tesla plans to start volume production of the Semi in the first half of 2026 at its factory expansion near Gigafactory Nevada, with a ramp-up in the second half and customer deliveries around that time. The truck, unveiled in 2017, has been tested by partners like PepsiCo, who report positive experiences with regenerative braking and power. However, deploying Megachargers nationwide poses grid challenges, potentially relying on Tesla's battery solutions.
This demonstration addresses key industry concerns about charging downtime compared to diesel trucks' 15-minute refuels, potentially enabling 400 miles of range during a 30-minute driver break.
