UL9540A Testing of Sodium Beta BatteriesAndrew K. Miraldi

FZSonick Inc.

UL9540A Test Method

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Test Method for Evaluating Thermal Runaway in Battery Energy Storage Systems, UL9540A

First Edition Dated November 2 , 2017

Summary of Topics‘...this test method evaluates the fire characteristics of a battery energy storage system that undergoes thermal runaway. The data generated will be used to determine a fire and explosion protection system required for an installationof a battery energy storage system.’

UL9540A Testing, Test process flow chart in the Standard

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UL9540A – UL Hazard Assessment flow chart available (?) to an AHJ

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UL9540A Sodium Beta Product at each level

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ML3XCell level

48TL200 Module level

Typical rackUnit level

Installation level

UL9540A Cell Level Testing

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Cell must be certified to UL1973 10 – Cell level test were completed All cells were cycled 10 times to verify operation and

preformance, Minimum 3 cycles required by test method

5 different methods were used to try to induce thermal runaway.

UL9540A Cell Level Testing Summary

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UL9540A Module Level Testing

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Module must be certified to UL1973. One module was tested twice to try to induce

thermal runaway. Module was cycled 3 times to verify operation and

preformance, Minimum 3 cycles required by test method.

Module needed to be mechanically altered to facititate the test method and instrumentation.

2 different methods were used to try to induce thermal runaway. Short circuit of a cell in the center of the pack Nail pentration of the out row of cells

UL9540A Module Level Testing, Modifications needed

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UL9540A Module Level Testing Summary

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UL9540A Testing Challenges

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Large amount of time was spent with UL educating them on the technology and technical details of the product by our technical team.

Test data is slightly skewed by the modifications and/or test conditions Cell level overheat test was done under

conditions that physically could not occur in a module design. Entrophy is in play, a phase change is thermodynamically not possible.

Module Insulation system was comprimised to allow for test and measurement leads. This allowed the very small amount of gas measured to escape a normally sealed container.

UL9540A Testing Challenges

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Costs Materials and test equipment Product to be sacrificed for the test Labor of technical staff UL Lab and tech time costs Potential responsibilty for cost of damage to lab

or facility if a test goes radically out of control. In our case this was in excess of $175K up to the

module level, unit level testing could potentailly quadruple this cost. Installation level test costs would be beyound any reasonable budget

UL9540A Post Report Challenges

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Report is very technical and has many pages of data for an AHJ to #1 review and #2 understand. The tests are NOT pass/fail so evaluation of the potential risk or hazard is still left up to the AHJ.

Still waiting for support from UL on a litmus test with the NYC area AHJ’s.

Promise of delivery of a guidance document for the AHJ from UL is continually being pushed out.

Even with the reports to the installation level, the flow chart advises the AHJ that a review of the fire protection plan and code requirements may necessitate review by a licensed fire protection engineer. See note 6 on flow chart.

UL9540A Conculsion

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Guidance to the +40K AHJ’s will most likely be required After test support from NRTL would be a benefit A guidance document from IEEE would be good but

may require the AHJ to purchase it. Still a lot of unknown challenges as the NFPA 855 is

adopted.

UL9540A Extreme Mechanical Damage Test

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Installation level event

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- External ground fault of 25,600 AH- 128 modules in parallel, 8 racks- Rack to rack spacing