Emergency Applications
Battery packs for emergency response applications have attributes unique to this use scenario. Emergencies, by definition, are unplanned, so the power system needs to keep this type of device ready at all times. Our battery packs for emergency equipment have advanced electronics and fuel gauging so that equipment can be kept ready at a moments notice and shelf life is maximized so that maintenance is minimal. Batteries, and the affiliated device, used in explosive environments must be intrinsically safe. Intrinsically safe batteries will not initiate and explosion should the electronic device malfunction while operating in areas that contain explosive gases or high dust concentration, so these are necessary for fire departments and other first responders. Examples of products that run on our custom battery packs include:
- Automatic External Defibrillators (AEDs)
- Defibrillators
- Automated CPR devices
- Portable oxygen concentrators
- Portable ventilators
- Radio systems
Fuel Gauging:
Traditional fuel gauges for Li-ion either monitored the voltage or the capacity, and the accuracy was quite limited. This is due to that flat discharge curve we saw earlier. New gas gauges monitor the number of coulombs being transferred and opportunistically calibrates with the open circuit voltage of the Li-ion pack. These features allow the end-user to intelligently manage device use and avoid unexpected failures or shutdowns. Accurate fuel gauging, combined with smart charging algorithms enable Li-ion packs to meet the needs of even life support applications.
Extended Shelf Life:
Micro Power designs and manufactures non-rechargeable battery packs based on Li-primary chemistry for our medical customer's disposable power solution needs. The Li-primary cells offer higher voltage than traditional alkaline cells, in addition to extremely long shelf life and superb performance in extreme temperature environments. With a negligible self-discharge rate, the li-primary cell is optimal for maintaining a high state of readiness. Micro Power's Li-primary battery packs can deliver full performance after being stored for five or even 7 years. Several different chemistries are available, such as lithium manganese dioxide, lithium sulfur dioxide and lithium thionyl chloride. A wide operating temperature range is offered by these chemistries, in addition to the long shelf life yielding products that are ideal for outdoor, emergency use.
Intrinsically Safe Batteries:
Intrinsically safe batteries prevent excessive heat buildup and eliminate the risk of an electric spark on equipment failure in an explosive environment. Potentially explosive environments include oil refineries, mines, grain elevators and fuel handling at airports. Therefore, a different set of engineering guidelines are applied to the design of an intrinsically safe battery. Several differences between conventional and intrinsically safe batteries include;
- The protection circuit prevents excessive current, which could lead to high heat and electric spark.
- Thermal fuses and electronics monitor the individual cells within the battery pack
- External pack temperature is limited during a potential short.
- External contacts are designed to prevent shorting when exposed to metal surfaces
- Potting material is injected into the battery pack enclosure to eliminate any air gaps.
- Specific material are selected for battery pack enclosure
There are several levels of intrinsic safety, each serving a specific hazard level, and the requirement for intrinsic safety varies from country to country. It is critical for the OEM to understand the degree of intrinsic safety required for the battery. Listed below are the different classes of intrinsic safety and the affiliated combustibles affiliated with each class;
Class I - Locations where there is a danger of explosion due to the presence of a flammable gas or vapor.
- Group A: Acetylene
- Group B: Butadiene, Hydrogen, Ethylene Oxide, Propylene Oxide
- Group C: Acetaldehyde, Ethylene, Cyclopropane, Ether Vapours, UDMH
- Group D: Acetone, Ammonia, Benzene, Butane, Butyl Alcohol, Butyl Acetate,Ethane, Eythl Acetate, Ethylene Dichloride, Gasoline, Heptane, Hexanes,Isoprene, Methane, Methanol, Ketones, Propanol, Petroleum, Octanes, Pentanes, Propane, Ethanol Propylene, Styrene, Toluene, Vinyl Acetate, Vinyl Chloride, Xylanes.
Class II - Locations where there is a danger of explosion due to the presence of a flammable dust.
- Group E: Metal Dust includes Aluminium, Commercial Alloys and Magnesium
- Group F: Carbon Black, Coal, Charcoal, Coke Dust
- Group G: Flour, Starch, Grain Dust
Class III - Location where there is a danger of explosion or flash fire due to presence of flammable fibers or particulates.
ATEX Directive 94/9/EC is a common safety directive that applies to devices used under these conditions. Since 2003, all new equipment intended for use in potentially explosive atmospheres must comply with ATEX, the most recognized directive. In order to ensure that a product meets essential safety requirements, manufacturers typically work with a third-party certification group, known as a Notified Body (for example, Factory Mutual or Underwriters Laboratories). Once certified, the equipment is marked with "CE" (meaning it complies with ATEX and all other relevant directives) and "EX" symbols to identify that it is approved under the ATEX Directive. The cost of certification contributes to the higher cost of intrinsically safe batteries.