UN GTR No. 25 on In-vehicle Battery Durability for Electrified Heavy Duty Vehicles provides harmonised methods to determine battery durability performance of HD-PEVs and HD-OVC-HEVs of categories M₁–M₃ and N₁–N₃ exceeding 3,855 kg MPLM. The regulation requires manufacturers to install State of Certified Energy (SOCE) monitors throughout vehicle lifetime. In-use verification consists of Part A verification of monitor accuracy through measured UBE testing using Methods 1a, 1b, Method 2 (bidirectional power supply), or an alternative HDV chassis dynamometer method, with statistical pass/fail criteria. Part B verification assesses battery durability against optional Minimum Performance Requirements (MPRs) through remote SOCE data collection from sample vehicles. Part C verification, reserved for future amendment, will address reported virtual distance accuracy for V2X, PTO and non-traction purpose applications. Optional Annex 4 specifies MPRs by vehicle category and mass, ranging from 45–70% SOCE retention across specified timeframes and distances. The GTR entered into force with Phase 1 covering core durability assessment and data collection to support future refinement of MPR thresholds based on in-service field data relating to HDVs, referencing WP.29-170-31 and GRPE/2026/3.

Proposal to revise the weight threshold of M₃ vehicle category from 7.5 tonnes to 12 tonnes, split N-type trucks into three categories with light-duty trucks below 5 tonnes, medium-duty trucks above 5 tonnes and N₃ below 18 tonnes, and heavy-duty trucks above 18 tonnes, adjust year and mileage limits for N₂, N₃ medium-duty trucks to 8 years or 500,000 km, and establish energy throughput requirements: M₂ 120,000 kWh, M₃≤12t 300,000 kWh, M₃>12t 500,000 kWh, N₂≤5t 200,000 kWh, N₂>5t, N₃≤18t 400,000 kWh, N₃>18t 1,200,000 kWh.

China introduces an assessment of low State of Charge Energy requirements for M-type vehicles using data from city buses and coaches. At low SOCE levels, available energy is reduced, requiring increased initial battery energy capacity to meet customer driving range expectations, leading to higher purchase costs and vehicle weight. China provides reasons supporting SOCE performance targets at an 8-year timeframe, including significant differences in vehicle types, operating conditions, business models, and battery specifications that vary by vehicle type, making uniform standards inefficient.

GTR 25 establishes alternative test and verification methods for heavy-duty vehicle energy consumption. China released test method GB/T 18386.2-2022 based on chassis dynamometers using continuous cycle and shortened methods. Test conditions include temperature of 25°C ± 5°C, initial battery SOC of 20%, and pre-conditioning soak and charge for minimum 6 hours and maximum 36 hours. The torque meter method measures road load without disabling regenerative braking, achieving resistance matching within 5% error. Test verification includes vehicle selection across mileage groups 0, 200,000, 400,000, and 600,000 km, with on-board data collection and sensor accuracy consistency analysis post-durability.

Under GTR 25, a feasibility assessment proposes introducing a 5-year mid-term performance requirement threshold together with corresponding mileage and energy-throughput limits as an intermediate verification checkpoint for battery degradation. Based on analysis of State-of-Health data from vehicles with 5-year life and mileage ranging from 250,000 km to 350,000 km, the MPR value is set at 75%, which can cover 98% battery-durability performance. Specific mileage and energy-throughput limits are established for vehicle categories M₂, M₃, N₂, and N₃.

This document proposes establishing a unified global testing method for determining system power and torque of heavy-duty hybrid electric vehicles (HD-HEV) and heavy-duty plug-in electric vehicles (HD-PEV). The proposal addresses the lack of standardized test methods by recommending hub-coupled dynamometer testing for vehicles with central drive systems and chassis dynamometer testing for other configurations. Testing should measure 30-minute continuous maximum power and torque under thermal equilibrium conditions. The document includes technical data from battery energy distribution analysis and recommends China lead formulation of this standard using chassis dynamometer verification.

The document addresses Part C verification of virtual distance for heavy-duty vehicle batteries. OICA reports pilot phase results from Volvo Group and Daimler Truck AG testing measurement procedures and accuracy under driving and stationary conditions. Key findings show measurement accuracy decreases significantly at lower power levels, with deviations of 0.3% to 4% at higher power. PTO system characteristics influence accuracy; internal PTOs performed better than bodybuilder-installed units. The document identifies challenges including formula correction needs, PTO family concept complexity, and proposes further testing before finalizing Part C requirements.

Japan proposes to add a specific requirement for vehicle speed measurement frequency of 20 Hz in Table A3/1 of Annex 3, consistent with UN R154; revise para. 2.4 to clarify that both constant and transient cycles test methods are permitted; delete redundant text from para. 2.4.1 regarding test cycle requirements; and delete from para. 5.1 the requirement that resolution and method for SOCE availability be determined in agreement with authorities, as these are already specified.