On December 24, 2024, with the final new-energy bus power battery successfully replaced and removed from production, Chengdu Airport Bus completed the smooth completion of its project to replace and extend the warranty on power batteries for all 120 Yutong plug-in hybrid buses. Currently, these vehicles have been gradually returning to their original routes and have been back in operation for more than half a month.

 

On-site replacement of the power battery

 

This follows the issuance of the "Implementation Details for Subsidies on Replacing New-Energy City Buses and Power Batteries," Document No. Jiaoyun Han [2024] 390, on July 29, 2024, marking Chengdu Airport Bus's bold exploration in swiftly responding to the subsidy policy. It also stands as the first demonstration case in the Southwest region, where large-scale initiatives for extended warranties and battery replacements of new-energy bus power systems have been launched since the subsidy policy was unveiled.

It is understood that the project was officially approved in early September 2024 and the official tender announcement was released on September 29. The project involves replacing 120 hybrid buses—specifically, Yutong-brand hybrid city buses originally purchased by Chengdu Airport Bus in 2016 (Announcement No.: ZK6850CHEVNPG21). These vehicles were initially equipped with lithium-manganese oxide power batteries supplied by CITIC Guoan Mengguli, featuring a battery system rated at 617.9V/35Ah with a total energy capacity of 21.63 kWh. The system consisted of two battery packs, housed in the rear cabin area atop the vehicle. To date, these buses have been in operation for over eight years, but their current pure-electric range no longer meets daily operational demands. Moreover, the batteries have experienced significant capacity degradation, and the vehicles are now beyond their warranty period. As a result, maintenance and upkeep have become increasingly frequent—and costly—posing considerable challenges to the continued smooth operation of the fleet.

Weihong Power Systems (Huzhou) Co., Ltd.

 

As a globally leading supplier of power-type battery systems, Microvast Power Systems (Huzhou) Co., Ltd. successfully won the bid for this project and promptly began signing agreements with the client while simultaneously finalizing the delivery schedule.

However, although the relevant authorities issued the "Announcement by the Ministry of Industry and Information Technology, Ministry of Transport, Ministry of Public Security, Ministry of Commerce, Ministry of Emergency Management, State Administration for Market Regulation, China Banking and Insurance Regulatory Commission, and National Fire and Rescue Bureau" on August 21, 2024, clearly stipulating that power battery replacement service providers must have legal entity status and adhere to the principle of "whoever claims responsibility, whoever replaces; whoever replaces, whoever takes charge," they subsequently released the "Supplementary Notice on Further Advancing the Renewal of New-Energy Urban Buses and Power Batteries" on September 24, 2024. This notice provides comprehensive guidance and support for the renewal process by outlining specific subsidy criteria, eligible vehicle types, applicant requirements, and detailed operational procedures. Nevertheless, it remains undeniable that extending the warranty and replacing power batteries in new-energy urban buses is a complex, highly technical, and systematic undertaking that demands the combined efforts and resources of multiple stakeholders to ensure its successful completion.

For example: First, after battery companies deliver their products, can they leverage local resources jointly to swiftly and efficiently carry out power battery replacement services?

Second: How will the vehicle-level communication protocols and wiring harness interface definitions involved in the original model be confirmed and implemented?

Third: How can we carry out wiring harness design without altering the original vehicle’s structural framework, thereby minimizing engineering complexity during the battery replacement process?

To this end, the four companies have joined forces to successfully establish a pioneering business model for extended warranties and battery replacements in new-energy bus power systems!

Four companies join forces to create an innovative model

 

Longxing Company Workshop

 

First, in order to maximize the implementation of its localization strategy, Chengdu Bus Group Longxing Automotive Technology Service Co., Ltd. (hereinafter referred to as “Longxing Company”) has taken the lead as the project’s first participating entity. As a wholly-owned subsidiary of Chengdu Bus Group, Longxing Company is the largest new-energy bus maintenance and repair base in Southwest China, equipped with a complete production process for new-energy buses as well as robust capabilities for vehicle remanufacturing. Longxing Company’s involvement marks an important step in Chengdu Bus Group’s ongoing efforts to pursue its “attract investment in and go global” strategy, encouraging its subsidiaries to diversify their operations and strive for outstanding performance. Moreover, it effectively addresses numerous challenges—such as site selection and construction—for replacing batteries on the 120 hybrid buses.

Power battery-related components installed in the roof-mounted battery compartment

 

Secondly, as one of the pioneering companies exploring extended warranties and battery replacements for domestic power batteries, Luoyang Dianniu New Power Technology Co., Ltd. (hereinafter referred to as "Luoyang Dianniu") has taken on the primary responsibility for the project's structural and wiring harness design. It is understood that the Luoyang Dianniu team primarily comprises technical and after-sales professionals from AVIC Lithium Battery (Luoyang) Co., Ltd., bringing with them over a decade of expertise in developing and applying power battery packs. "As early as 2021, we proactively responded to market demands by launching extended warranty and replacement services for power cells tailored to select domestic customers," said Yang Wei, Chairman of Luoyang Dianniu. "By 2023, our company had successfully been approved as a provincial-level high-tech enterprise in Henan Province, laying a solid foundation for our future growth." In his view, the Chengdu Airport Bus Project represents a collaborative effort involving multiple stakeholders—battery system manufacturers, bus operators, and maintenance units—a multi-party initiative that fully leverages the unique strengths of each participant. This approach not only significantly reduces the costs associated with extending warranties and replacing batteries but also enhances the safety and reliability of these services. Ultimately, it sets an important benchmark for building a more robust after-sales service framework for new-energy vehicles in the future.

Third, Chengdu Dianchehui New Energy Technology Co., Ltd. (hereinafter referred to as "Dianchehui") also provided critical technology and data support for this project. Building upon a clear identification and confirmation of historical announcements and recommended catalog information for the corresponding vehicle models, it was further verified that these models are equipped with Yutong Bus's second-generation Ruikong powertrain system launched after April 2016—and feature the standard interface specifications delivered directly from Yutong Bus's complete vehicle platform. Moreover, within the fully integrated data framework that seamlessly combines the My-SQL database with Tableau visualization software, the verification of the aforementioned data was completed in just a matter of minutes.

In 2025, Electric Vehicle Hub celebrates its 13th year of operation—and it marks a pivotal year as the company’s data system begins to unlock its full potential. Against the backdrop of ongoing adjustments in new-energy vehicle subsidy policies, Electric Vehicle Hub remains the only domestic service provider that has successfully implemented unified data fields for recommended new-energy vehicle models, enabling seamless, collaborative access to vehicle registration data. Meanwhile, in this project, the Electric Vehicle Hub team worked closely with teams from Luoyang Dianniu, Microvast Power Systems, and Longxing Company. Without making any modifications to the original Vehicle Control Unit (VCU), they smoothly integrated their independently developed CAN repeater solution, effectively resolving all technical communication challenges between Microvast’s power battery system and the vehicle’s original control architecture—while preserving the vehicle’s original wiring harness to the greatest extent possible.

 

 

CAN Repeater Physical Diagram

 

Battery replacement requires clear technical details.

Taking this project as an example, Microvast Power has adopted soft-pack multi-component composite lithium batteries with individual cells rated at 48 Ah, configured in a 1P171S architecture. The entire system consists of one standard battery box and a high-voltage module, delivering a nominal voltage of 632.7V and a total energy capacity of 30.3 kWh. Importantly, the system features a brand-new BMS and control system—fully compatible with remote OTA updates. The product’s overall performance significantly outperforms and surpasses the original vehicle’s power battery system. With the support of Luoyang Dianniu, Dianchehui, and Longxing companies, the newly installed batteries seamlessly integrate into the vehicle via a CAN repeater, ensuring perfect compatibility with the original car’s BMS communication protocol. This integration not only enhances the efficiency of the overall structural and wiring harness design but also provides critical support for optimizing the entire vehicle installation and assembly process.

 

Based on the data comparison above, the redesigned solution fully meets the vehicle's operational requirements. In addition to an increased capacity of approximately 9 kWh compared to the previous design, the voltage level now perfectly aligns with current standards. All other parameters either meet or exceed the overall vehicle specifications. Moreover, the safety parameters are now superior to those previously used, with some even surpassing the original design criteria. Each battery pack can also be equipped with a fire suppression system, which, in extreme scenarios, will provide effective protection.

Extended warranty and replacement for power batteries hold promising prospects ahead.

In fact, the subsidy policy offering an "8-year warranty" for power batteries has been around for quite some time!

As early as April 29, 2015, the "Notice on Fiscal Support Policies for the Promotion and Application of New Energy Vehicles from 2016 to 2020" (Cai Jian [2015] No. 134) was issued, requiring new energy vehicle manufacturers to provide consumers with quality guarantees for energy storage devices such as power batteries, as well as for drive motors and motor controllers. Specifically, passenger car manufacturers must offer a warranty period of no less than 8 years or 120,000 kilometers—whichever comes first (the same applies hereinafter)—while commercial vehicle manufacturers (including buses, special-purpose vehicles, trucks, and others) are required to provide a warranty of at least 5 years or 200,000 kilometers. Moreover, both automobile manufacturers and power battery producers are held primarily responsible for the recycling and reuse of retired power batteries. In the subsequent market expansion phase, BYD and CATL took the lead by announcing an industry-first policy: an 8-year warranty on all their power batteries. This move officially ushered in the "8-year" era for domestic new-energy vehicle power battery warranties. Meanwhile, bolstered by the "Notice on Improving the Subsidy Policy for Finished Oil Prices of Urban Buses and Accelerating the Promotion and Application of New Energy Vehicles" (Cai Jian [2015] No. 159), released on May 11, 2015, subsidies for operating new-energy urban buses gained significant traction, triggering a wave of nearly one million new-energy bus replacements across cities. However, this supportive policy officially ended in 2021, marking the cessation of operational subsidies for new-energy urban buses. As a result, local governments became less enthusiastic about encouraging bus companies to phase out conventional vehicles and switch to new-energy models, leading to a noticeable slowdown in the replacement of urban buses with their new-energy counterparts. Meanwhile, referring to the "Regulations on Mandatory Scrapping of Motor Vehicles," approved at the 68th Ministry Meeting of the Ministry of Commerce in 2012, Article 5 explicitly stipulates that public transportation buses can be used for up to 13 years. Consequently, power batteries that have already exceeded their initial 8-year warranty period will no longer meet the safety standards required for bus operations, prompting a surge in demand for extended warranties and battery replacements among urban bus operators.

According to an incomplete tally by Dianchehui, by 2025, more than 250,000 new-energy buses of various types nationwide are expected to undergo extended warranties and battery replacements. Most of these vehicles are plug-in and pure-electric city buses that were primarily registered between 2015 and 2016. Dianchehui has now compiled and organized the registration data from provinces and cities across the country, along with the corresponding vehicle configuration details.