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.

The agenda for the Electric Vehicles and the Environment Informal Working Group 98th session scheduled for July 15, 2026, includes presentations on battery performance, discussions on UN GTR 21, UN GTR 22, and UN GTR 25 regulatory topics including minimum performance requirements, state of charge reference, readiness monitor and conditioning cycles, mutual recognition, fuel cell electric vehicles, highly integrated systems, energy throughput, normal usage indices, and battery replacement provisions. UN GTR 25 amendment 2 must be submitted to March 2027 GRPE with a December 2026 deadline.

Proposal to establish harmonised methods for in-vehicle battery durability of electrified heavy-duty vehicles:

• Establish harmonised methods for determining in-vehicle battery durability of electrified heavy-duty vehicles (categories 1-2 and 2 with technically permissible maximum laden mass exceeding 3,855 kg) that are pure electric or off-vehicle charging hybrid electric vehicles,
• Require manufacturers to install and maintain State-of-Certified Energy (SOCE) monitors throughout vehicle lifetime at resolution of at least 1 part in 100, making values available via on-board diagnostics port and optionally over-the-air,
• For Contracting Parties electing to enforce minimum performance requirements from optional Annex 4, require manufacturers to ensure compliance through in-use verification comprising Part A (monitor accuracy verification through measured usable battery energy testing via driving on test track/road or bidirectional power supply system, with statistical pass/fail criteria) and Part B (battery durability verification through remote data collection from vehicle sample of minimum 500 vehicles annually, requiring at least 90 per cent of monitored values above applicable minimum performance requirement or declared performance requirement),
• Reserve Part C verification of virtual distance accuracy for future amendment,
• Specify minimum performance requirements with SOCE retention percentages (45–70 per cent) at defined time and distance combinations varying by vehicle category and mass, to be monitored during phase 1 for potential future revision based on energy throughput data.

The Electric Vehicles and the Environment Informal Working Group held its 97th session on May 19, 2026. Discussions addressed UN GTR 22/25 including Norwegian EV demographics, a proposed Readiness Monitor concept for State of Certified Energy activities, and OICA terminology amendments replacing “monitor” with “assessment of virtual distance” in Part C. The group reviewed Phase 4 priorities for UN GTR 21 and UN GTR 25, including Minimum Performance Requirements, conditioning cycles, and lifetime requirements addressing disconnects between mileage and year thresholds. The next session is scheduled for June 16–17, 2026.

The document presents Norway’s electrification progress for light duty vehicles (LDVs) and heavy duty vehicles (HDVs). Norway has 994,000 electric LDVs and 5,300 electric HDVs from a total fleet of 3.4 million LDVs and 73,000 HDVs. In April 2026, EV market share reached 98.6 percent with 107 municipalities achieving 100 percent market share. The document reports EVs represent 2-7 percent of registered vehicle fires, with fossil fuelled vehicles accounting for up to 90 percent. Research findings indicate battery degradation is driven by operating conditions, with cold climate introducing dual effects and battery management systems being key durability drivers.

UN GTR No. 25 addresses minimum performance requirements, lifetime requirements, and metrics for heavy-duty vehicles. Lifetime requirements are 12 years and 700,000 km or 15 years and 875,000 km for Category 1-2 vehicles exceeding 7.5 tonnes and Category 2 vehicles exceeding 16 tonnes. An optional annex proposes different metrics including years, kilometres whichever comes first, and energy throughput in monitoring. Capacity retention requirements for N₃ vehicles exceeding 16 tonnes are specified at 12 years and 700,000 km and at 15 years and 875,000 km.

The session is scheduled for May 19, 2026, from 05:30 to 08:00 EDT. The agenda includes discussion of UN GTR 22 and UN GTR 25 regulatory topics covering conditioning cycles, SOCE readiness monitor, MPRs, SOCR, mutual recognition, FCEVs, highly integrated systems, efficient test methods, OICA comments, MPRs and energy throughput, normal usage indices, Part C virtual distance verification, Annex 2 alternative test method, and battery replacement provisions. UN GTR 25 Amendment 2 must be submitted to March 2027 GRPE by December 2026 deadline.

UN GTR No. 21 Phase 4 will consider fuel-cell electric vehicles, measurement alternatives for highly integrated systems, modifications for more efficient test methods, and alignment with UN Regulation No. 177 based on inputs EVE-87-08e, EVE-87-09e, EVE-87-11e, EVE-88-12, EVE-85-06e, and EVE-74-10e. UN GTR No. 22 Phase 4 will explore conditioning cycles and readiness monitors for official testing, investigate minimum performance requirements for certified range, and consider establishing minimum performance requirement values for additional lifetime of ten years and 200,000 km, drawing on input EVE-96-06e. UN GTR No. 25 Phase 3 will amend Annex 2 provisions, verify reported virtual distance, reconsider minimum performance requirements regarding mileage and lifetime thresholds, and consider energy throughput as a threshold.

The 96th EVE IWG session was held online on April 21, 2026. Discussions covered Alliance des Mobilites’ battery state of health and state of certified energy monitoring findings; UN GTR No. 21 priorities including fuel cell electric vehicles and highly integrated systems; UN GTR No. 22 objectives on state of certified range and minimum performance requirements; and UN GTR No. 25 pilot phase testing and normal usage indices for heavy-duty vehicles. Action items included presentations on battery data, fuel cell vehicle proposals, test method efficiency, and electrified vehicle data from Norway.

The agenda includes presentations on UN GTR 21 covering highly integrated systems, FCEVs, and more efficient test methods; UN GTR 22 addressing MPRs, SOCR, readiness monitor and conditioning cycles, and mutual recognition; and UN GTR 25 with OICA comments and updates on MPRs/Energy throughput, Part C virtual distance verification, Annex 2, alternative test methods, normal usage indices, and battery replacement provisions.

The document outlines work priorities for UN GTR 21, 22, and 25 amendments. UN R21 Phase 4 will address fuel-cell electric vehicles, measurement alternatives for integrated systems, test method efficiency, and alignment with UN R177. UN R22 Phase 4 will explore conditioning cycles, readiness monitors, certified range performance requirements, and alignment with UN R154-04 and UN R83-09. UN R25 Phase 3 will consider Annex 2 amendments, virtual distance verification, minimum performance requirement thresholds by vehicle category, and alternative test methods.

Document also available with tracked changes.

This document is also available with tracked changes.

This document is also available with tracked changes.

This document is also available with tracked changes.