1. Testing & Conformity Assessment for Energy Storage Systems
Ken Boyce
Principal Engineer Director
Energy & Power Technologies
UL LLC

2. Why Energy Storage?
Recently, enormous focus has been placed on expanding the energy storage infrastructure. The benefits of energy storage are driven by several dynamic factors.

3. Kahuku, Hawaii 2012

4. The Invisible Foundation
Good standards serve as the foundation for successful technology deployment, addressing safety, interoperability and clear expectations
Environmental & Energy Goals
Market Success
Standards
Codes & Regulations

5. Testing and conformity assessment of energy storage systems are critical for safety
Safely managing high energy density under normal and abnormal conditions must be demonstrated Connections to the electric grid and buildings present dynamic and demanding conditions of use Integration into the infrastructure must be coordinated to minimize the risk of unintended consequences over the life of the energy storage system Some approaches used elsewhere may help the South African technical community find the best solutions

6. Testing Criteria

7. Fluid containment tests
Overview of UL 9540 Tests
EES system tests
Electric tests
Mechanical tests
Fluid containment tests
Environ-mental tests
Although most testing would be covered by the technology specific standards, UL 9540 does include some testing for those technologies that may lack specific criteria. As noted above, the tests are divided into electrical tests, mechanical tests fluid containment tests and environmental tests.

8. Overview of UL 9540Tests Electric tests Normal operations
2 cycles of charge/discharge
Measure temps
Ensure limits are not exceeded
Dielectric voltage withstand
Per UL electric strength test
Impulse
1.2/50 sec pulse of voltages per table
Applied between circuit under test and accessible parts
Equipment Grounding and bonding
Test per NFPA 79 or UL method
≤ 0.1Ω in grounding circuit
Insulation resistance
Insulation between hazardous circuit and accessible parts ≥ 1 MΩ
Apply 500 V dc for 1 minute and measure resistance
Although most testing would be covered by the technology specific standards, UL 9540 does include some testing for those technologies that may lack specific criteria. As noted above, the tests are divided into electrical tests, mechanical tests fluid containment tests and environmental tests.

9. Overview of UL 9540Tests Mechanical tests Blocked shaft
Over speed test
Single fault that can lead to an over speed condition.
Parts are not loosened or disconnected to cause a hazardous condition
Faulted securement test
Moving parts are subjected to single fault in securement and then rotated
Blocked shaft
Block shaft of moving part for 30 min max, protection operates, or breaking off of a part
Although most testing would be covered by the technology specific standards, UL 9540 does include some testing for those technologies that may lack specific criteria. As noted above, the tests are divided into electrical tests, mechanical tests fluid containment tests and environmental tests.

10. Overview of UL 9540Tests Mechanical tests Abnormal Speed Test Leakage
a margin of safety of a factor of at least 2.0
Leakage
Leakage of Hazardous gas
Leakage of hazardous liquid
Strength
Hydrostatic strength
Pneumatic strength
Although most testing would be covered by the technology specific standards, UL 9540 does include some testing for those technologies that may lack specific criteria. As noted above, the tests are divided into electrical tests, mechanical tests fluid containment tests and environmental tests.

11. Overview of UL 9540Tests Environmental tests
Outdoors installations subject to moisture exposure
IEC 60529, UL 50E, CSA C22.2 No per rating
Electrical Insulation tests after conditioning
Check for water in side on components, etc.
Outdoor installation near marine environments
Salt Fog test of IEC for Severities 1 of 2.
Examination for signs of damage as a result of salt fog exposure
Installation in seismic environments
Evaluated for ability to withstand seismic events per rating
examined for signs of explosion, fire, combustible concentrations (if applicable to technology), rupture of the enclosure, electrolyte leakage, electric shock and loss of protection controls that may lead
Although most testing would be covered by the technology specific standards, UL 9540 does include some testing for those technologies that may lack specific criteria. As noted above, the tests are divided into electrical tests, mechanical tests fluid containment tests and environmental tests.

12. Testing Facilities
Testing of energy storage systems presents some unique challenges Safety of personnel and the facility is critical when testing battery technologies, especially large format and especially in fault modes Expertise in BMS technology is imperative Grid connection testing requires significant testing equipment and expertise of the technicians

13. Safety of large format batteries: UL 1973 vs. IEC 62619
UL 1973 Construction Requirements
IEC Construction Requirements
Scope: Safety, Non-technology specific and covers lithium ion, LA, Nickel, Sodium Beta, Flow Battery and Ultra-capacitor technologies for stationary and LER applications
Covers very generic safety criteria for lithium ion cells and batteries for industrial use (stationary and off road motive)
Material requirements affecting safety
N/A
Gaskets & Seals requirements if affecting safety
Enclosures, ingress, accessibility to hazardous parts and material requirements
Electrical system requirements
Systems safety analysis (FMEA)
Included
Protective circuits and controls including functional safety
Cooling/Thermal Management System requirements
Electrolyte Containment Parts and Parts subject to pressure
Cells and Capacitors: covers various technologies and ultra-capacitors (Annex E cell program similar to IEC with some exceptions)
lithium ion cell tests only
Nameplate & Cautionary Marking Requirements
IEC nameplate, general info on cautionary
Instructions for installation, operation and maintenance
Very general instruction information

14. UL 1973 – IEC 62619 UL 1973 Test Requirements
IEC Test Requirements
Tests General: Monitor for insulation deterioration through repeat of dielectric voltage withstand test, determine combustible concentrations and potential toxic venting, include 1 hour observation period after test, conduct charge/discharge cycle if battery is still operational after test to determine no hazards resulting from operation
N/A
Overcharge -Attempt overcharge of battery to > then 110% of maximum charge voltage, single fault (SF)
Overcharge control test for voltage controls and current controls
Short Circuit -Subject battery to hard short at ≤ 20 mΩ and then repeat with loading below trip point of SC protection , SF
Short circuit is only at the cell level. No short circuit at the battery level.
Over-discharge Protection -Continue discharging discharged pack for 30 minutes after reaching end of discharge voltage or until protection operates, SF
Evaluated at cell level only
Temperature and Operating Limits Check -Charge/discharge cycle battery for 2 sets of cycles at maximum load and consideration for max ambient and measure temperatures and parameters of modules/cells

15. UL 1973 – IEC 62619 UL 1973 Test Requirements
IEC Test Requirements
Imbalanced Charging -create artificial imbalance of a cell or module in discharged pack by leaving 50% SOC and then charge pack
N/A
Dielectric Voltage Withstand -voltage withstand test per IEC electric strength test parameters
Continuity -measure impedance of grounding circuit either through ohmmeter measurements or through measurements of voltage drops when running current through circuit.
Failure of Cooling/Thermal Stability System -fail cooling/thermal stability system to determine if hazards occur
Overheating control test addresses similar concern
Working Voltage Measurements -measure voltages at circuits to determine suitable spacing criteria and dielectric withstand test voltages
Strain Relief -156 N pull on external cord at anchorage for 1 minute
Push Back Relief -push external cord back at anchorage for 26.7 N force
Static Force N static force on battery enclosure for 5 seconds.
Impact -6.8 J ball impact of battery enclosure
Drop Impact - Drop field installed modules or packs onto hard surface from designated height which varies with wait of device
Drop impact test is similar to UL 1973
Wall Mount/Handle - Handle or wall mount fixture to be able to support 4 times weight of device for 1 minute

16. UL 1973 – IEC 62619 UL 1973 Test Requirements
IEC Test Requirements
Mold Stress - UL 746C 7 h aging test of polymeric enclosure
N/A
Pressure Release -Evaluation of relief mechanism in a VRLA or valve regulated nickel battery per UL 1989 method
Start-to-Discharge -Evaluation of pressure relief valve
Resistance to Moisture -Resistance to moisture based upon IP rating of enclosure, tests per IEC or can do UL 50E enclosure tests
Salt Fog -IEC Salt Mist test for Severity 1 or 2
External Fire -Hydrocarbon Fuel Pan Fire exposure for 30 minutes followed by hose down
Internal Fire -Propagation test for lithium and sodium technologies – under revision to include other technologies and provide details regarding cell failure methods. Name of test changing to “Single Cell Failure Tolerance” and will be taken out of the environmental test. New appendix developed for cell failure methods.
Propagation Test similar to internal fire test of UL 1973 however, can waive propagation test for cell particle test (FISC)
Forced Internal Short Circuit (FISC) Test - Particle cell test which is option to replace propagation test. Consists of pressing on exposed cell electrode assembly that contains a small particle.

17. For Lithium ion battery systems
UL 1973 – IEC 62619
UL 1973 Test Requirements
IEC Test Requirements
Production Tests - Dielectric Voltage Withstand, Continuity,
N/A No production testing noted, but does have criteria regarding quality program for production.
Special Technologies
Sodium Beta: Cell Test program for sodium sulfur and sodium nickel chloride, etc. cells -
short circuit, abnormal charging, shock (mechanical), vibration, heating, temperature cycling,
N/A (lithium ion only)
Flowing Electrolyte Batteries, Flow battery stack tests - vibration, shock, and short circuit
N/A
Flowing Electrolyte Battery: Additional tests specifics with regard to testing flow batteries - hydraulic pressure, leakage, electrolyte blockage, short circuit, shunt current determination, spill containment
For Lithium ion battery systems
UL 1973  IEC IEC IEC

18. Other standards of note for energy storage
The IEC series, Recommendations for renewable energy and hybrid systems for rural electrification, addresses equipment for isolated use in producing and distributing electricity UL 9741 was developed to address “V2X” technology for exporting power from electric vehicle batteries UL 1974 is being developed to address repurposing of electric vehicle batteries into the stationary energy storage infrastructure in a “second life” UL 3001 is being developed to address microgrids

19. Conformity Assessment

20. Conformity Assessment
Conformity assessment is essential to establish initial and ongoing adherence to important requirements such as safety Battery technologies generally have low failure rates, but the energy density and significant consequences for large scale energy storage installations require ongoing confidence in the supply chain Best practices include placing a conformity assessment scheme in place to address both certification and ongoing production

21. Interface with Codes and Regulations
Coordinating testing and certification to product standards with an overarching codes and regulatory structure promotes optimal integration This establishes clear rules for how certified products and systems need to be imported, sited, installed, commissioned and operated These requirements can address electrical aspects, how to integrate into a building with respect to fire safety and structural integrity, grid compatibility, and the like

22. Code developments
NFPA 70, the National Electrical Code, added new requirements in the 2017 Edition to address energy storage systems and DC microgrids, requiring certification NFPA 855 is being developed to address building and fire safety considerations for integrating energy storage systems The International Fire Code (IFC) was revised to include rules for installing energy storage systems into buildings, identifying limits, certification, fire suppression and setbacks Grid codes continue to evolve, but the evolution to “smart inverters” with advanced technology will offer better grid management for the future

23. Other efforts related to energy storage
UL is leading work to with interested parties to continue refinement of methods to assess the risk of fire starting within and propagating UL is working with leaders in industry and the fire service to assess the risk of an external fire engaging an energy storage system Work continues in the broader fire community to address the best methods for fire suppression involving energy storage technologies

24. Summary
Energy storage has brought may benefits to the global energy infrastructure There are standards and codes that may serve as a model to help South Africa develop the optimal approach for its people and country Work continues on finding the best way to address the needs of all stakeholders – consumers, owners, manufacturers, utilities, government, insurers, first responders and others – for energy storage

25. Thank you Ngiyabonga Dankie Ken Boyce Kenneth.p.boyce@ul.com