GB/T 45797-2025 in English

Standard Overview and Technical Framework

GB/T 45797—2025, "Performance Requirements and Test Methods for Low-Voltage Electrical Systems of Road Vehicles," is a key technical standard jointly issued by the State Administration for Market Regulation and the Standardization Administration of China, and will be officially implemented in 2025. This standard specifies the performance requirements for a vehicle's 12V/24V low-voltage electrical system and describes the corresponding test methods. It applies to Class M and N vehicles, and other types of vehicles can follow suit.

Analysis of Core Technical Requirements

Quiescent Current Requirements

The standard requires obtaining the quiescent current of the vehicle and each controller, checking for any undesigned quiescent current, and assessing whether the vehicle meets transportation time requirements and starting requirements after prolonged storage. After testing in accordance with 6.5, the vehicle's quiescent current, the quiescent current of components such as controllers, and the vehicle's quiescent current under different usage scenarios should not exceed the design values.

Electricity Balancing Technical Requirements

This standard evaluates the rationality of power system selection by analyzing the relationship between power generation and consumption between batteries, generators or DC/DC converters, and electrical loads. Lead-acid battery SOC variation and transient voltage must comply with the standard. Other battery requirements can be determined through negotiation between the supplier and the buyer.

Low-temperature cold engine starting requirements

The standard evaluates the low-temperature cold engine starting performance of vehicles and puts forward differentiated requirements for different types of vehicles:

• Internal combustion engine vehicles and hybrid electric vehicles: The number of continuous starting tests should not exceed the requirements of GB/T12535-2021
• Pure electric vehicles, extended-range electric vehicles, etc.: The vehicle should be able to start normally or the "READY" signal device should be normally illuminated and remain on for at least 1 minute

Test method system

Test conditions and equipment requirements

The standard stipulates that all tests should be carried out at 23℃±5℃ and relative humidity of 25%~75%. The allowable error of the measuring equipment must meet the standard requirements, and the equipment sampling frequency should not be lower than 10Hz.

Special test methods

Quiet current test

Includes static current tests on components such as vehicles and controllers, and static current tests in different scenarios. The resolution of the current monitoring device is required to be no less than 0.01mA (vehicle) and 0.001mA (component).

Electrical Balance Test

Refer to Appendix C to select test conditions and load configurations. Calculate the battery SOC change using the formula ΔSOC = (I·t/Cn) × 100% to comprehensively evaluate power system performance.

Load Dump Test

Examines the impact of voltage pulses generated when a vehicle experiences a load dump under varying battery SOC and engine speed conditions. The voltage pulse peak value and duration must meet standard requirements.

Recommendations for the implementation of the standard

Vehicle manufacturers

Vehicle manufacturers are advised to establish a complete low-voltage electrical system test system in accordance with the requirements of the standard, especially to strengthen quality control in the following aspects:

• Establish a quiescent current monitoring mechanism to ensure the vehicle's sleep current meets design requirements.
• Improve the electrical balance test process and optimize power system matching.
• Strengthen wiring harness system reliability verification to ensure proper matching of fuses and loads.

Testing Organizations

Testing organizations should configure appropriate testing equipment in accordance with standard requirements and establish standardized testing procedures, paying particular attention to the control of test conditions and the accuracy requirements of measuring equipment.

Supplier Management

Component suppliers should provide relevant performance data and technical support in accordance with standard requirements and cooperate with vehicle manufacturers to complete system-level verification.

Technological Evolution and Development Trends

With the continuous improvement of the degree of automotive electrification, the complexity of low-voltage electrical systems is increasing. This standard conforms to the trend of technological development and demonstrates its advancement in the following aspects:

• Comprehensiveness: Covers a full range of performance requirements, from quiescent current to load dump
• Practicality: Provides detailed test methods and evaluation criteria
• Foresight: Takes into account the special requirements of new energy vehicles
• Flexibility: Allows supply and demand parties to negotiate and determine some technical requirements

The implementation of this standard will effectively promote the improvement of the technical level of low-voltage electrical systems for road vehicles in my country and provide important technical support for improving vehicle reliability and safety.