Mitigating Risk of Battery Testing in Environmental Chambers Mark Chrusciel & Wayne Diener Cincinnati Sub-Zero Chrusciel@cszinc.com
First You Must Select the Right Environmental Chamber for Your Application The first steps are yours Type of Application What are you trying to do? Document your Requirements Write a Specification or reference your specification (sections that apply) Communicate with Supplier Designate a Primary Contact
What do You Need to Know (Defining the Application) What is being tested? Materials of construction, weight and configuration of DUT Are there fixtures involved? Is it powered, how much and when? Is the material hazardous? Is the requirement long or short term? Can impact solution and cost Do you want minimum or maximum transition rates EIC 61646
What do You Need to Know (Defining the Application) What is the temperature range? -34ºC to -40ºC is the practical limit of single stage -40ºC to -54ºC is the practical limit of two-stage or Tundra -73 o C for cascade Or LN 2 for lower temperatures What is your high temperature requirement? What is required ramp rate? Speed is money; how fast do you want to go? Air temp or part temp Linear rate or average rate Be sure to specify not only the minimum highs and lows, but also what range your test will be in
What do You Need to Know (Defining the Application) Are there air flow requirements? Part temperature requires high velocity air flow Does part configuration dictate air flow requirement? Will a standard chamber work? Is temperature uniformity a requirement? Live load? On during transitions?
What do You Need to Know (Defining the Application) Is humidity required? Standard range is 10-98% Low end limited by 5-7ºC dew point High end by 85ºC dry bulb Extended ranges is 5-98% Frozen coil and dry air purge required High end by 95ºC dry bulb Special requirements Maintained RH during transitions Live loads and RH
What do You Need to Know (Defining the Application) Any special requirements? Explosion Proof Local and State Codes Facility or Corporate standards MIL-STD s, IEC or UL specifications Sound power levels Regulatory agencies Test and Acceptance? Testing with customer product Customer witnessed testing Most vendors welcome this
What do You Need to Know (Defining the Application) What utilities are required? Power Water Air LN 2 What utilities are available? Are there move-in restrictions? Do you want installation/start-up/training?
Critical Equipment Decisions Chamber Types Cooling Options Humidification Options Air Flow Controllers
Chamber types Based on your application what works best? Conventional temperature or temp & RH chamber Air to air thermal shock Modular walk-in or welded walk-in Liquid thermal shock Stress screening or HALT & HASS Altitude simulation with & w/o temp. and/or RH Liquid conditioners Storage many types Custom Clean sheet of paper
Cooling Options Expendable Refrigerant Liquids/gases that can be injected directly into the space being cooled Two most popular refrigerants are: Liquid Nitrogen (LN2)» Cryogenic temperatures down to -184 o C Liquid Carbon Dioxide (CO2)» Temperature down to -68 o C Mechanically Cooled Use a compressor and circulate a refrigerant around a closed-loop system The ultimate low temperature required by your testing determines the type of refrigeration system needed.
Mechanical Refrigeration Options Single Stage: -34 o C Traditional single stage refrigeration system is rated to -40 o C However, due to the refrigerant used there is very little cooling capacity at -40 o C Tundra and Two-Stage Systems: -40 o C to -54 o C Cascade: -73 o C Two separate systems working to cool the chamber down
Refrigeration Decisions Compressors: Semi-Hermetic (7-1/2 to 30 hp) Hermetic (1 to 3 hp) Scroll ( 2 to 15 hp) Tandem Configurations Integral Water-or-air cooled condenser Options: Remote Power Pack Remote air-cooled condenser
Methods of Humidity Generation Boiler - Good generator, should not be used with live loads Atomizer - Good control, especially with live loads, but must be very clean Water Pan - Very stable, but slow response
Air Flow The airflow must have enough volume to support the refrigeration system. Typical air velocity in most reach-in chambers is approximately 100 ft/min through the work space This velocity works well for steady-state and temperature-cycling testing Air velocity across the part should be much higher to keep it closer to the chamber air temperature during transitions 500 ft/min or more is required It is a necessity in thermal shock applications to have airflow this high
Current Technology Touch Screen Controllers Ethernet Control & Monitoring Controller Types Automated Alarm Notifications via email or text message. Automated back-up of data files Program the profile in one chamber and import to the others to saving valuable profile entry time. Integrated email sends data files directly to an email address from the controller with a touch of a button. Data logging - Easily download profiles, alarm files, audit trail files and data files to a removable USB stick. Full system security allows up to 30 users with three levels of security. X-Y Graphs (Real Time & Historical) Autostart Product Control
CAUTION More Bang for the Buck Generic choices aren t always the best choices If It s too good to be true, it probably is too good to be true The lowest price isn t always the best choice. You get what you pay for Where did the corners get cut? Compare Apples to Apples Are you getting the same thing? Used Chambers Can be a great deal but one service call can negate savings.
Batteries - What do we Need to Know?
What is the chemistry and the hazards? What specification do they have to run? Heat load? How is it done now? What is the failure mode?
Different Chemistries Lead Acid NiCD NiMh Li ion Hydro and Oxy Hydro and Oxy Hydro and Oxy Carbonates
Safety In each individual case the risk must be determined by the customer This information will allow us to determine what safety equipment must be installed. There is no standard safety equipment, as the risks may vary considerably.
Lithium Ion Gases not as much an issue as thermal runaway Self sustaining Short period of intense heat and pressure
Typical Failure Modes of Li-ion Batteries Cracks in membrane separating anode and cathode. Could also be a short caused by defect in production Over heating Over charging Under charging
Typical Tests Charge and discharge at high and low temperatures Temperature Cycling Altitude Humidity Vibration Batteries then tested to see if they lost charge or efficiencies
Cell Testing GM Corporation
Published Specifications UL 1642 General Safety testing of Li-ion batteries. IEC 61960 Safety standards for secondary Li-ion batteries. SAE J2464 General guidelines for rechargeable energy storage. UN/DOT 38.3 Standards for shipping lithium batteries.
Published Specifications IEC 62281 Safety of primary cells during shipment. UL 2580 Batteries for use in Electric Vehicles. IEC 62660-2 Reliability and abuse testing of secondary cells. IEC 62133 Testing of secondary cells.
Pack Testing GM Corporation
IEC 62133 Section 4.2.2 Vibration 4.2.4 Temperature cycling 30 minute ramps. Also High ambient and high temperature tests.
62133
Safety In each individual case the risk must be determined by the customer This information will allow us to determine what safety equipment must be installed. There is no standard safety equipment, as the risks may vary considerably.
Safety Options Temperature limited sheath heaters Standard ni-chrome wire heaters can reach temperatures of 540C. Temperature is set below auto ignition temp. of gases Non sparking fan blades or blower wheels Aluminum construction Intrinsically safe barriers preventing the potential of high voltage pulses. Fire suppression Inert Atmosphere Use of N2 or CO2 to eliminate Oxygen does not prevent thermal runaway but can help contain Liquid cooling Used to cool cells or packs if they overheat-may help prevent thermal runaway.
Safety Options Reinforced chamber floor To support weight and extreme temperatures Oversized pressure relief vent Protects chamber from a sudden release of high pressure gas. Rapid air exchange system Aids in removing all gases from inside the chamber prior to opening the door can be vented to the outside Gas monitors O2, H2, CO etc Can be interlocked to controller to shut down chambers-may need to be conditioned prior to sensing Safety door interlock Prevents entry either during tests or after an event Protective enclosure/structure for tests to failure. External structure that would contain any fire or explosion.
Conclusion Understand your products and it s failure modes and consequences. Communicate to your equipment/chamber suppliers and they will work with you to design a safe system.
Questions
Thank You Mark Chrusciel Cincinnati Sub-Zero chrusciel@cszinc.com