Tesla electric vehicle in a HORIBA test cell for battery durability testing | UN GTR No. 22

Battery Testing

What is UN GTR No. 22?

Understanding In-Vehicle Battery Durability for EVs Under UN GTR No. 22

United Nations Global Technical Regulation — UN GTR No. 22 — deﬁnes the framework for testing and evaluating the durability of in-vehicle batteries, speciﬁcally for battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs). These requirements are being integrated into upcoming environmental standards such as Euro 7 in the EU and Tier 4 in the US.

What is In-Vehicle Battery Durability?

In-vehicle battery durability refers to regulatory standards for maintaining the performance of electric vehicle batteries over time. These standards aim to ensure that batteries retain a minimum level of energy capacity and driving range throughout the vehicle's lifespan.

These requirements are set to be adopted under key environmental regulations, including:

Euro 7 — EU Regulation 2024/1257
Tier 4 — EPA MY2027+ LD/MD Multi-Pollutant Emissions Standard

UN GTR No. 22: In-Vehicle Battery Durability Testing Method

Established by the United Nations on March 9, 2022, UN GTR No. 22 provides a standardized global approach to battery durability testing. This regulation applies to battery electric vehicles (BEV) and plug-in hybrid vehicles (PHEV) for passenger cars and light commercial vehicles.

Minimum Performance Requirements (MPR)

MPRs deﬁne the acceptable rate of battery degradation over the life of a vehicle. These standards are designed to ensure that electriﬁed vehicles maintain reliable battery performance throughout their usable lifespan.

SOCE and SOCR: Key Indicators

Battery durability is evaluated using two primary indicators:

State-of-Certiﬁed Energy (SOCE) measures the percentage of usable battery energy retained as the battery ages.
State-of-Certiﬁed Range (SOCR) assesses the percentage of the original certiﬁed driving range that remains over time.

Vehicle manufacturers must make both SOCE and SOCR values accessible to users, either through the On-Board Diagnostics (OBD) port or via Over-the-Air (OTA) updates. While UN GTR No. 22 establishes deﬁned thresholds for SOCE, the oﬃcial criteria for SOCR are still pending and will be determined in future updates.

Battery Energy-Based MPR (SOCE):

Vehicle Type	Mileage/Age	SOCE Threshold
BEV & PHEV (Category 1-1, 1-2: Passenger Cars)	≤ 5 years or 100,000 km	≥ 80%
BEV & PHEV (Category 1-1, 1-2: Passenger Cars)	> 5 years or ≤ 8 years / 160,000 km	≥ 70%
BEV & PHEV (Category 2: Commercial Vehicles)	Reserved	Reserved
_{Note: The earlier of time or distance is applied. Based on UN GTR No. 22 as interpreted by HORIBA.}

Overview of UN GTR No. 22 Testing

The following section outlines the test methods used to determine the SOCE, using a BEV as a representative example.

What is SOCE?

State of Certiﬁed Energy (SOCE) is deﬁned as the ratio of a battery’s on-board Usable Battery Energy (UBE) at a speciﬁc point in its life to the certiﬁed UBE determined during initial testing.

UN GTR No. 22 equation for calculating SOCE as the ratio of measured to certified usable battery energy | Battery Durability Testing

For example: If the certiﬁed UBE = 50 kWh. And the measured UBE = 40 kWh. Then SOCE = 80%.

UBE is determined through laboratory testing using the Worldwide Harmonized Light Vehicles Test Procedure (WLTP). A shortened version of this procedure—combining the WLTC and constant-speed phases—is used to evaluate battery performance, as shown in Figure 1. The vehicle begins from a fully charged state and is driven through the test cycle until it can no longer follow the prescribed driving proﬁle due to battery depletion. This point is deﬁned as the test termination criterion.

Throughout the test, changes in the vehicle’s State of Charge (SOC) are monitored, as illustrated in Figure 2. The UBE is the total amount of electrical energy consumed from the start of the test to the point at which the battery can no longer sustain operation. This value serves as a basis for calculating the SOCE.

"UN GTR No. 22 battery durability testing diagram showing shortened WLTP drive cycle used to evaluate BEV energy consumption.

^{Figure 1. A8/2 from UN GTR No. 15 – Example of a shortened WLTP test cycle for a BEV (PDF Document)}

UN GTR No. 22 battery durability testing graph illustrating SOC changes during a shortened WLTP test cycle for a BEV.

^{Figure 2. A8.App1/7 from UN GTR No. 15 – Example of SOC changes during a shortened WLTP test cycle for a BEV (PDF Document)}

In-Use Veriﬁcation

In-use veriﬁcation is carried out in two parts to conﬁrm that the vehicle continues to meet battery durability requirements throughout its lifetime.

Part A – Monitor Veriﬁcation
The accuracy of the on-board SOCE display is veriﬁed through laboratory testing. A WLTP test is conducted to measure the actual UBE, which is then compared to the displayed SOCE value.

Part B – Battery Durability Veriﬁcation
Using the SOCE readings veriﬁed in Part A, the vehicle’s battery durability is assessed to ensure that the SOCE remains within the Minimum Performance Requirements (MPR).

This two-step process ensures that the SOCE values monitored during regular use reliably reﬂect the vehicle’s battery performance over time.

Future Outlook

The battery durability standards outlined in UN GTR No. 22 are being progressively integrated into regional regulations across key markets including Europe, North America (under CARB and EPA), and Japan.

In parallel, development is underway for durability test methods speciﬁc to heavy-duty vehicles, led by the WP.29-GRPE-EVE working group.

HORIBA’s Evaluation Solutions for UN GTR No. 22

HORIBA oﬀers advanced tools to streamline and automate WLTP testing for determining UBE. Our systems and software are designed to reduce testing time and operator workload, while delivering high accuracy and repeatability for both BEVs and PHEVs.

Automated calculations minimize manual input and help ensure consistent results. Additionally, our solutions support real-time, shortened test procedures by automatically calculating Constant Speed/State Monitoring (CSSM) durations based on actual EV power consumption—eliminating the need for preconditioning tests.