Analysis of BYD's 1MW Fast Charging System

Key Points

• BYD's 1MW charging stations, released on March 17, 2025, can charge up to 400 km of range in 5 minutes, using a 1000V architecture and 1000A current.

• The charging rate reaches 1MW between 11% and 26% state of charge (SoC), then decreases with multiple constant current stages, likely for battery safety and heat management.

• The system relies on advanced LFP batteries, refrigerant-based cooling, and nearby Battery Energy Storage Systems (BESS) for high power delivery.

• It seems likely that thermal management and battery health are key factors limiting constant 1MW charging, with an average power around 534 kW for a 375 km range increase in 5 minutes.

Introduction

BYD, a prominent player in the electric vehicle (EV) market, unveiled its 1MW (1000 kW) fast charging stations on March 17, 2025, as part of its Super e-Platform, aiming to revolutionize EV charging speeds. This system, branded as the "Megawatt Flash Charger," promises to add 400 km of range in just 5 minutes, aligning EV charging times with traditional gas refueling. The first 500 units were rolled out on March 26, 2025, with plans for 4000 across China, eliciting a strong positive response in the EV market (BYD to roll out first 500 ultrafast 1000 kW charging stations in April, 4000 set for China). This note analyzes the charging power versus state of charge (SoC) graph from the launch, exploring how this technology works and its implications. BYD claims the station is capable of handling 1360kW of power, and considering the charging voltage should be higher than 1000V, station's energy efficiency and cooling requirement needed, this might be right.

Technical Specifications

The charging system operates on a 1000V architecture with a maximum current of 1000A, achieving a 10C charge rate. It is designed for passenger EVs like the BYD Han L and Tang L, which feature an 83.2 kWh Lithium Iron Phosphate (LFP) battery pack, offering a full range of up to 701 km (CLTC). The system relies on advanced thermal management and Battery Energy Storage Systems (BESS) at charging stations to deliver such high power (BYD released 10C megawatt charging stations in China).

Charging Curve Analysis

The charging behavior, as observed in the launch video, shows a non-linear power delivery:

• Initial Phase (SoC ~8%): The charging rate starts at 728 kW, one of the highest rates seen in passenger cars, indicating a ramp-up phase.

• High-Power Phase (SoC 11% to 26%): The rate reaches 1MW at 11% SoC and remains constant until 26% SoC. This segment corresponds to an energy addition of approximately 12.48 kWh (15% of 83.2 kWh), taking about 45 seconds at 1000 kW.

• Reduced Power Phase (SoC 26% to ~62.5%): After 26% SoC, the rate decreases in multiple constant current (CC) stages, likely to manage heat and ensure battery health. The user noted this continues until around 62.5% SoC, with an average power of about 545 kW for the later stages.

In a 5-minute charging session, the range increased by 375 km, slightly less than the claimed 400 km, possibly due to specific test conditions. This corresponds to an energy addition of approximately 44.5 kWh in the battery pack, calculated as (375/701)*83.2 ≈ 44.5 kWh, with an average power of 44.5 / (5/60) ≈ 534 kW.

Energy and Time Breakdown

To understand the distribution:

• SoC 8% to 11%: SoC increase of 3%, energy added ≈ 2.496 kWh. Assuming an average power of (728 kW + 1000 kW)/2 ≈ 864 kW, time taken ≈ 2.496 / 864 ≈ 0.00289 hours ≈ 0.1734 minutes (≈10 seconds).

• SoC 11% to 26%: SoC increase of 15%, energy added ≈ 12.48 kWh at 1000 kW, time ≈ 12.48 / 1000 ≈ 0.01248 hours ≈ 0.7488 minutes (≈45 seconds).

• SoC 26% to 61.5%: Remaining time ≈ 5 - (0.1734 + 0.7488) ≈ 3.0778 minutes, energy added ≈ 29.524 kWh (total 44.5 - 14.976), average power ≈ 29.524 / (3.0778/60) ≈ 575 kW, aligning with multiple CC stages.

This suggests the system optimizes for high power initially, then reduces to balance heat and battery longevity.

Supporting Technologies

• Battery Chemistry: The LFP batteries are optimized for fast charging, with stability and safety advantages over NMC packs, though traditionally slower. BYD's short blade battery cells enhance this capability (How BYD plans to make EV charging as fast as filling a gas tank).

• Thermal Management: BYD's refrigerant-based cooling system is designed to manage the high heat generated during fast charging, especially at rates up to 1MW. It uses a refrigerant (we don't know which one it is), a fluid known for excellent heat transfer, circulated through the battery pack to keep temperatures optimal. Unlike traditional liquid cooling systems that use water-glycol mixtures, a refrigerant-based system can offer more efficient heat removal, especially under high-power conditions. This is evident from reports indicating BYD's use of direct cooling and heating with refrigerants, as seen in models like the BYD SEAL, which features a heat pump system for battery temperature regulation (BYD SEAL: Dynamic and Intelligent).

• The system features cooling plates on both the top and bottom of the battery cells, ensuring even heat distribution. This dual-sided approach helps prevent hotspots, which is vital for large-format Blade batteries during rapid charging.This setup enhances thermal management by providing cooling from both sides, which is more effective than single-sided cooling, especially for high-power applications. The dual-sided approach is an advancement over previous Blade battery designs, which primarily had top cooling, as noted in earlier analyses (BYD Blade - Battery Design).

• BESS Integration: Charging stations use BESS for high power delivery, mitigating grid strain, with each station potentially charging two cars at 500 kW each via dual guns.

Comparison with Industry Standards

Current fast chargers typically offer up to 350 kW, with Tesla's V3 Superchargers at around 350 kW. BYD's 1MW system triples this, aligning with emerging standards like the second-generation GB/T (Chaoji) at 900 kW (1500V, 600A). However, BYD's approach is unique in integrating vehicle and station technology for passenger cars, unlike Megawatt Charging System (MCS) developed for heavy commercials and VTOLs.

Challenges and Future Implications

• Infrastructure: Deploying 4000 stations requires significant investment in BESS and grid upgrades, potentially expensive (BYD's 5-Minute EV Charging Sounds Great. But How Useful Is it?).

• Battery Longevity: High charging rates may impact battery life, though BYD's cooling and LFP chemistry mitigate this.

• Standardization: High-power charging may need new connector standards, with dual-gun systems adding complexity.

Unexpected Detail

Interestingly, BYD tested dual-gun charging on commercial vehicles three years ago, showing a continuity in their innovation, which might not be widely known among casual EV enthusiasts, as seen in the Denza D9 implementation (BYD Denza doubles up on charging power).

Conclusion

BYD's 1MW charging system represents a significant advancement, leveraging high-voltage architecture, advanced batteries, and thermal management to achieve unprecedented charging speeds. The charging curve shows a strategic approach to balance speed and safety, with potential to reduce range anxiety significantly. As infrastructure expands, this could redefine EV adoption, though challenges in scalability and standardization remain.