In March 2025, Beijing Benz announced a recall of 12,308 domestically produced EQA and EQB electric vehicles due to fluctuations in the high-voltage battery production process, resulting in reduced reliability, and defective battery management system (BMS) software, which may cause a short circuit or even fire risk. This is the third high-voltage system recall of the Mercedes-Benz EQ series in recent years, the first two involving coolant leakage and motor insulation failure.
In contrast, although Tesla recalled 2 million vehicles worldwide in 2023 due to self-driving software issues, it has never had a large-scale recall due to battery safety issues; BYD has maintained a record of zero major battery accidents in the past three years by virtue of blade battery technology.
Why does Mercedes-Benz frequently step on pits, while Tesla and BYD can avoid these safety hazards? In this article, China Exportsemi will deeply analyze the manufacturing process, thermal management, BMS software, and platform architecture from four dimensions, and reveal the technical differences behind the safety of high-voltage batteries for electric vehicles.
1. Manufacturing process: Mercedes-Benz's "quality control fluctuation" vs CATL's "industrial-grade precision".
The "fluctuation of production process" mentioned by Mercedes-Benz in the recall announcement seems to be an understatement, but it actually exposes the shortcomings of traditional car companies in battery manufacturing.
- Mercedes-Benz's battery production mode:
- Semi-automated production line is adopted, and some links rely on manual intervention, resulting in problems such as uneven electrode coating and impurity mixing.
- Only 500 tests are performed on each cell, while the standard of CATL, the industry leader, is 2000+, including X-ray scanning, laser thickness measurement and other precision tests.
- A similar issue occurred during the 2022 BMW iX3 recall, when BMW admitted that the battery module was poorly welded and caused a power outage while driving.
Figure:Mercedes' Recall and the Battery Safety Dilemma
- CATL and BYD's quality control strategy:
- Fully automated "black light factory" (no artificial lighting required), cleanliness up to medical grade, to ensure zero pollution in the production environment.
- Lifetime ID traceability of each battery allows any issues to be pinpointed to the production batch, equipment or even the operator.
- BYD's blade battery has no open flame or explosion in the acupuncture test, while traditional ternary lithium batteries will burn violently under the same conditions.
Conclusion: Mercedes-Benz's manufacturing process is more like a "handicraft workshop", while Chinese and South Korean battery giants have entered the "Industry 4.0" era, and the quality control gap directly determines safety performance.
2. Thermal management: Mercedes-Benz's "leakage disease" vs Tesla's "structured cooling".
One of the core issues of the Mercedes-Benz EQ series recalls is a short circuit in the high-pressure system caused by coolant leakage.
- Mercedes-Benz's oil-to-electric architecture defects:
- Based on the transformation of the platform of fuel vehicles, the battery layout is limited, the cooling pipeline winding is complicated, and the long-term vibration can easily lead to the loosening of the interface.
- Coolant can corrode the insulation once it penetrates the motor or battery pack, which can cause a short circuit in extreme cases.
- A similar issue occurred with the Audi e-tron, whose liquid-cooled system had been subject to a mass recall due to poor sealing.
- Tesla's solution:
- The 4680 battery is structured cooled, and the cooling plate is directly integrated into the battery pack, and there are no external piping, which completely eliminates the risk of leakage.
- Up to 30% higher thermal runaway rejection than conventional designs, even if a single cell fails, it will not spread to the entire battery pack.
- Tesla's battery pack can withstand direct jetting from a high-pressure water gun (IP67 standard), while the Mercedes-Benz EQ series only meets the basic waterproof rating.
BYD's "refrigerant direct cooling" technology goes a step further by directly replacing the coolant with refrigerant, increasing the cooling speed by 20% and completely avoiding the risk of liquid leakage.
Conclusion: Mercedes-Benz's cooling system design stays in the "fuel vehicle thinking", while Tesla and BYD have entered the era of "integrated thermal management".
3. BMS software: Mercedes-Benz's "passive remedy" vs BYD's "AI early warning".
Another key issue in Mercedes-Benz's recall is a defect in the battery management system (BMS) software, which makes it impossible to correct the risk of overload in a timely manner.
- Shortcomings of Mercedes-Benz BMS:
- The control strategy is lagging behind, and the charging strategy cannot be adjusted in real time, so you need to rely on the recall upgrade software.
- SOC (Power Estimate) error of up to 5% can lead to overcharging or overdischarging, accelerating battery aging.
- A similar problem exists in the Volkswagen ID. series, where some owners complain that the battery level is inaccurate and the power suddenly loses.
- BYD's BMS technology:
- Cloud-based AI health monitoring, early warning of more than 80% of battery abnormalities, and the error is controlled within 3%.
- Learn the charging habits of different users through big data and dynamically optimize battery life.
- BYD owners can check the battery health at any time in the APP, while Mercedes-Benz owners can only wait for the 4S store to notify the recall.
Tesla's OTA Advantages:
- In 2023, Tesla fixed 70% of software issues through remote upgrades, without the need to enter the store.
- BMS can learn driving habits independently, such as users who charge frequently and quickly, and the system will automatically adjust the charging strategy to protect the battery.
Conclusion: Mercedes-Benz's BMS is still in the era of "feature phones", while Tesla and BYD have entered the stage of "intelligent AI".
4. Platform architecture: Mercedes-Benz's "oil-to-electricity compromise" vs the "intrinsic safety" of the pure electric platform
The Mercedes-Benz EQ series is based on the transformation of the fuel vehicle platform, while Tesla, BYD, and NIO all use pure electric exclusive platforms, and this fundamental difference determines the safety ceiling.
- Birth defects of Mercedes-Benz oil to electricity:
- The battery pack is irregularly shaped and forced to "cut through the seams", and the protection level is only IP67 (anti-short-term immersion).
- Weak crash protection, chassis rigidity is 30% lower than that of pure electric platforms.
- Similar issues plague the Volvo XC40 Recharge, where the battery pack has a high risk of deformation in a side impact test.
- Advantages of the BEV platform:
- Tesla's integrated die-cast body: The battery pack is fused with the body to increase torsional rigidity by 50%.
- NIO NT2.0 platform: The battery pack is IP69K waterproof (resistant to high-pressure steam washdown).
- BYD e-platform 3.0: Adopts a "honeycomb aluminum" structure, and the collision energy absorption efficiency is 20% higher than that of the Mercedes-Benz EQ series.
Conclusion: Switching from oil to electricity is the transition plan for traditional car companies, but the pure electric platform is the ultimate answer to safety.
5. Future trends: How can the industry avoid the next "Mercedes-Benz recall"?
1. Solid-state batteries: mass production after 2025 to completely eliminate the risk of electrolyte leakage.
2. Dynamic security standards: Existing national standards (such as GB 38031) need to add long-term aging and software vulnerability testing.
3. Optimization of user habits: For example, Mercedes-Benz recommends that the charging limit be set to 80%, which may become the industry standard in the future.
Final Conclusion
Mercedes-Benz's recall is by no means accidental, but a typical dilemma of traditional car companies in the transformation of electrification. In contrast, Tesla and BYD have built a more reliable safety system through intelligent manufacturing, integrated thermal management, AI BMS, and pure electric platforms.
The numbers don't lie:
- The failure rate of Mercedes-Benz EQ series is 0.8%, and BYD blade battery is only 0.02%.
- Tesla saves billions of dollars in recall costs through OTAs.
The competition of electric vehicles is essentially the competition of safety. If Mercedes-Benz wants to truly break through, it must give up the compromise of "oil to electricity" and fully transform to the original pure electric architecture. Otherwise, the list of future recalls will only get longer and longer.
