Standard ANSI/CAN/UL/ULC 2271-2023 edition, applying to battery safety testing for Light Electric Vehicle (LEV), was published in September 2023 to replace the old standard of 2018 version.This new version of the standard has changes in definitions, structural requirements, and testing requirements.

Changes in definitions

• Addition of Battery Management System (BMS) definition:A battery control circuit with active protection devices that monitors and maintains the cells within their specified operating region: and which prevents overcharge, overcurrent, overtemperature, under-temperature and overdischarge conditions of the cells.
• Addition of Electric Motorcycle definition: An electric motor vehicle having a seat or saddle for the use of the rider and designed to travel on not more than three wheels in contact with the groud, but excluding a tractor. An electric motorcycle is intened for use on public roadways including highways.
• Addition of Electric Scooter definition: A device weighing less than one hundred pounds that:

a) Has handlebars, a floorboard or a seat that can be stood or sat upon by the operator, and an electric motor;

b)Can be powered by the electric motor and/or human power; and

c)Has a maximum speed of nomore than 20 mph on a paved level surface when powered solely by the electric motor.

Modification of the LEV examples: Electric motorcycle is removed and unmanned aerial vehicles (UAV) is added.

• Addition of Personal E-mobility Device definition: A consumer mobility devide intened for a single rider with a rechargeable electric drive train that balances and propels the rider, and whcih may be provided with a handle for grasping while riding. This devide may or may not be self-balancing.
• Addition of definitions of Primary Overcurrent Protection, Primary Safety Protection, Active Protective devices, and passive protective devices.
• Addition of Sodium Ion Cells definition: Cells that are similar in construction to lithium ion cells except that they utilize sodium as the ion of transport with a positive electrode consisting of a sodium compound, and carbon or similar type anode with an aqueous or non-aqueous and with a sodium compound salt dissolved in the electrolyte.(Examples of sodium ion cells are Prussian Blue cells or transition metal layered oxide cells)

Changs in structure requirements

Metallic Parts Resistance to Corrosion

1.Mental electrical energy storage assemblie (EESA) enslosures shall be corrosion resistant. Metal enclosures made of the following materials shal be considered to comply with the corrosion resistance requirements:

Copper, aluminum, or stainless steel; and

b) Bronze or brass, either of which containing at least 80% copper.

2.Addition of corrosion resistance requirements for ferrous enclosures:

Ferrous enclosures for indoor application shall be protected against corrosion by enameling, painting, galvanizing, or other equivalent means. Ferrous enclosures for outdoor application shall comply with the 600-hour salt spray test in CSA C22.2 No. 94.2 / UL 50E. Additional methods to achieve corrosion protection according to CSA C22.2 No. 94.2 / UL 50E can be accepted.

Insulation Levels and Protective Grounding

Compliance of the protective grounding system can be evaluated according to the new intelligent test item of this standard – grounding continuity test.

Safety Analysis

1.Addition of examples of safety analysis. A system safety analysis must prove the following conditions are not hazardous. The following conditions shall be considered at a minimum, but are not limited to:

a) Battery cell over-voltage and under-voltage;

b)  Battery over-temperature and under-temperature; and

c) Battery over-current duing charge and discharge conditions.

2.Modification of safety protection device (hardware) requirements:

a)The Farilure-Mode and Effect Analysis (FMEA) requirements in UL 991;

b)The Protection Against Internal Faults to Ensure Functional Safety requirements in UL 60730-1 or CSA E60730-1 (Clause H.27.1.2); or

c)The Protection Against Faults to Ensure Functional Safety requirements (Class B requirements) in CSA C22.2 No.0.8 (Section 5.5) to determine compliance and identify tests necessary to verify single fault tolerance.

3.Modification of safety protectin doevide (software) requirements:

a) UL 1998；

b)Software Class B requirements of CSA C22.2 No.0.8; or

c)The Contrils Using Software requirements (Software Class B requirements) in UL 60730-1 (Clause H.11.12) or CSA E60730-1.

4.Addition of BMS requirements for cell protection.

If relied upon for maintaining the cells within their specified operating limits, the battery management system (BMS) shall maintain cells within the specified cell voltage and current limits to protect against overcharge and over-discharge. The BMS shall also maintain cells within the specified temperature limits providing protection from overheating and under temperature operation. When reviewing safety circuits to determine that cell operating region limits are maintained, tolerances of the protective circuit/component shall be considered in the evaluation. Components such as fuses, circuit breakers or other devices and parts determined necessary for intended operation of the battery system that are required to be provided in the end use LEV, shall be identified in the installation instructions.

Addition of protection circuit requirements.

If specified operating limits are exceeded, a protective circuit shall limit or shut down the charging or discharging to prevent excursions beyond operating limits. When a hazardous scenario occurs, the system shall continue to provide the safety function or go to a safe state (SS) or risk addressed (RA) state. If the safety function has been damaged, the system shall remain in the safe state or risk addressed state until the safety function has been restored and the system has been deemed acceptable to operate.

Addition of EMC requirements.

Solid state circuits and software controls, relied upon as the primary safety protection, shall be evaluated and tested to verify electromagnetic immunity in accordance with the Electromagnetic Immunity Tests of UL 1973 if not tested as part of the functional safety standard evaluation.

Cell

1.Addition of requirements for Sodium ion cells. Sodium ion cells shall comply with the sodium ion cell requirements of UL/ULC 2580 (identical to the performance and marking requirement for secondary lithium cells in UL/ULC 2580), including compliance with all the performance tests for cells.

2.Addition of requirements for repurposed cells. Battries and battery systems using repurposed cells and batteries shall ensure that the repurposed parts have gone through an acceptable process for repurposing in accordance with UL 1974.

Testing Changes

Overcharge Test

• Addition of requirement that during test, the voltage of the cells shall be measured.
• Addition of the requirement that If BMS reduces the charging current to a lower valve near the end of charging phase, the sample shall be charged continually with the redued charging current until ultimate results occur.
• Deletion of the requirement that if the protection device in the circuit activates, the test shall be repeated for at least 10 minutes at 90% of the trip point of the protection device or at a certain percentage of the trip point that allows charging.
• Addition of requirement that at a result of the overcharge test, the maximum charging volatge measured on the cells shall not exceed their normal operating region.

high rate charging

• Addition of a High Rate Charge Test (same test requirements as UL 1973);
• BMS delay is also considered in the test result: The overcharging current may exceed the maximum charging current for a short duration (within a few seconds) which is within the delay time of the BMS detection.

Short Circuit

• Eliminates the requirement that if a protective device in the circuit operates, the test is repeated at 90% of the trip point of the protection device or at some percentage of the trip point that allows charging for at least 10 min.

Overload Under Discharge Test

• Addition of Overload Under Discharge Test (test requirements are the same as UL 1973)

Overdischarge

• Addition of the requirement that the voltage of the cells shall be measured during the test.
• Addition of the requirement that as a result of the overdischarge test, the minimum discharge voltage measured on the cells shall not exceed their normal operating range.

Temperature Test (Temperature rise)

• Addition of the requirement that if the maximum charging parameters vary with temperature, the correspondence between charging parameters and temperature shall be clearly specified in the charging instructions and the DUT shall be charged under the most severe charging parameters.
• Change the requirement of pre-condition. The charge and discharge cycles are then repeated for a minimum total of 2 complete cycles of charge and discharge, until consecutive charge and discharge cycles do not continue to increase the maximum cell temperature more than 2 °C。(5 charge and discharge cycles are required in the old version)
• Addition of the requirement that thermal protection and overcurrent protection devices shall not operate.

Grounding Continuity Test

Addition of Grounding Continuity Test (test requirements are the same as UL 2580)

Single Cell Failure Design Tolerance Test

Secondary lithium batteries that have a rated energy greater than 1kWh shall be subjected to the Single Cell Failure Design Tolerance Test of UL/ULC 2580).

Summaryy

The new version of UL 2271 cancels electric motorcycles in the product range (electric motorcycles will be included in the scope of UL 2580) and adds drones; with the development of sodium-ion batteries, more and more LEVs use them as power supply. The requirements for sodium-ion cells are added into the new version standard. In terms of testing, test details have also been improved and more attention has been paid to the safety of cell. Thermal runaway has been added for large batteries.

Previously, New York City had mandated that batteries for electric bicycles, electric scooters, and light electric vehicles (LEV) must comply with UL 2271. This standard revision is also to comprehensively control the battery safety of electric bicycles and other equipment. If companies want to successfully enter the North American market, they need to understand and meet the requirements of the new standards in a timely manner.