Flammability Characterization of Li-ion Batteries in Bulk Storage Benjamin Ditch Global Research Update: High Challenge Storage Protection 22 May 2014, London, England
Goal Develop sprinkler protection recommendations for bulk storage of Li-ion batteries
Markets Automotive industry Consumer electronics Power tools
How to Evaluate Li-ion Batteries Large-scale evaluation not feasible Provides direct evaluation of protection Requires multiple pallets loads Commodity expensive and difficult to acquire Reduced commodity approach Limit commodity to one pallet load per test Freeburn (no water)
Combustible Product (Li-ion batteries or standard commodity) Ring burner Non-combustible Rack storage configuration 3-tier storage Single-row rack Commodity lining ignition flue Bottom tier non-combustible Simulate fire from 1 st tier Propane ring burner, ~50 kw 5 MW Fire Products Collector Side Elevation View Ignition flue
Reduced-Commodity Approach 1. Estimate time-of-involvement of Li-ion Batteries Time in fire development where the batteries are observed to contribute to the fire severity 2. Characterize fire development up to theoretical sprinkler operation 3. Compare predicted sprinkler operation time versus time of battery involvement Ditch, B. and de Vries, J., Flammability Characterization of Lithium-ion Batteries in Bulk Storage, FM Global Research Technical Report, March 2013, http://www.fmglobal.com/researchreports
Heat Release Rate FM Global Fire Growth Comparison High Hazard Sprinkler operation Low Hazard Time
Commodities Baseline and Li-ion Batteries
Baseline Commodity Class 2 Cartoned Unexpanded Plastic
Array Configuration [50 kw] Class 2 Cartoned Unexpanded Plastic
Cylindrical Cells 19,200 cells total Cobalt oxide
Power Tool Battery Packs 200 power packs total 2,000 cells total Nickel mang. cobalt oxide
Polymer Cells 15,552 cells total Cobalt oxide
Results and Analysis
Fire Development 30 s 90 s 360 s 480 s Characterization period 75 ± 5 s for each commodity
Convective Heat Release Rate (kw) FM Global Heat Release Rate 5000 CUP - Test 7 Class 2 - Test 10 4000 3000 2000 1000 0 0 60 120 180 240 300 360 420 480 540 600 Time (s)
Convective Heat Release Rate (kw) FM Global Heat Release Rate 5000 4000 3000 2000 1000 0 CUP - Test 7 Class 2 - Test 10 Li-ion Cylindrical Cells Li-ion Power Tool Packs Li-ion Polymer Cells 0 60 120 180 240 300 360 420 480 540 600 Similar initial fire growth rate Packaging and mass impacts fire growth Involvement observed for polymer and cylindrical cells Time (s)
Sprinkler Link Response Measure convective flow from fire Calculate fire plume temp and velocity Rack storage height Clearance above commodity Calculate response of sprinkler link Link rating and response
QR Sprinkler Response Fire size @ sprinkler operation Quick-response sprinkler, 74 o C link rating, 3 m clearance (165 o F link rating, 10 ft clearance )
Rack Storage Configuration Configuration Units Value Sprinkler RTI m 1/2 s 1/2 Link Rating Ceiling Clearance [ft 1/2 s 1/2 ] o C [ o F] m [ft] 27.6 and 170 [50 and 300] 74 [165] 3.0 and 4.6 [10 and 15]
QR Sprinkler, 3 m (10 ft) Clearance Commodity Link Operation Time (s) Q be (kw) Fire Growth Rate (kw/s) Class 2 59 209 15 CUP 43 232 16 Li-ion Cylindrical Cells Li-ion Power Tool Packs Li-ion Polymer Cells Fire size at sprinkler operation, Q be (kw) 44 284 23 51 282 25 41 256 16
Compiled Sprinkler Response (s) Commodity 3 m (10 ft) Ceiling 4.6 m (15 ft) Ceiling QR SR QR SR Class 2 59 77 65 - CUP 43 70 52 - Li-ion Cylindrical Cells Li-ion Power Tool Packs Li-ion Polymer Cells 44 62 76-51 70 - - 41 64 77 - Excludes all sprinkler operation times greater than 75 ± 5 s
Convective Heat Release Rate (kw) FM Global Battery Involvement 5000 4000 3000 2000 CUP - Test 7 Class 2 - Test 10 Li-ion Cylindrical Cells Li-ion Power Tool Packs Li-ion Polymer Cells Based on HRR curves Cylindrical cells: ~ 4-6 minutes Polymer cells: ~ 5-8 minutes Power tool packs: not discernable Nominal value: 5 minutes 1000 0 0 60 120 180 240 300 360 420 480 540 600 Time (s) Threshold values based on steady-state contribution from commodity, excluding Li-ion batteries Ditch, B., Yee G. and Chaos M., 2014. Estimating the Time-of-Involvement of Bulk Packed Lithium-Ion Batteries in a Warehouse Storage Fire, Fire Safety Science 11, 2014.
Convective Heat Release Rate (kw) FM Global A Timeline for Protection 5000 4000 3000 2000 1000 0 5 Suppression 4 1 2 3 0 240 480 720 960 Time (s) 1. QR link 2. SR link 3. Batteries involved 4. Partial collapse 5. Fire fighting
Conclusions Initial fire growth similar for all commodities Dominated by carton material Battery involvement: Expected within 5 min after ignition Occurs after sprinkler operation Not observable for power tool packs Sprinklered fire tests needed with Li-ion batteries
Protection Recommendations Sprinkler protection recommendations, based on: Included in FM Global Technical Report Li-ion battery hazard assessment at sprinkler operation Commodities with analogous hazard characteristics, e.g., fire growth, projectiles, reignition, etc. Small format Li-ion batteries Cartoned in bulk storage
Disclaimer Unique test approach only used due to availability of Li-ion batteries Does not provide same information as Commodity Classification or sprinklered fire testing Protection recommendations may be amended with additional research specific to Li-ion battery hazard
Special Thanks to: Exponent, Inc. Property Insurance Research Group FM Global More Data at www.fmglobal.com/researchreports www.nfpa.org/foundation www.youtube.com Search: lithium ion, FM Global