The standard, “RTCA DO-293 Minimum Operational Performance Standards for Nickel-cadmium, nickel-metal-hydride, and lead-acid batteries,” developed by the Radiotechnical Commission for Aviation (RTCA), provides guidance to aviation electronics manufacturers developing nickel-cadmium, nickel-metal-hydride, and lead-acid batteries used as power sources for aircraft-mounted equipment. The standard specifically addresses chemical composition, cell size, cell structure, cell attachment to batteries, ventilation, operational and storage environments, packaging, handling, testing, storage, and disposal. The latest update to this standard includes new nickel-metal-hydride guidance and significant changes to address testing concerns identified by industry.
For aircraft safety, such batteries and component cells must perform as designed and operate safely in their applications. In the United States, the Federal Aviation Administration (FAA) is the primary regulatory authority for aviation and is responsible for developing, implementing, and enforcing regulations to protect people. This responsibility extends to regulating portable energy products that are considered part of an aircraft. In aviation, the development of such standards is often coordinated through the Radiotechnical Commission for Aviation (RTCA). This organization has developed a number of standards over time to address different chemistries. The RTCA DO-293 standard is one of these.
Nickel-cadmium batteries (NiCd or NiCad) are a type of rechargeable battery that uses nickel oxide hydroxide and metallic cadmium as electrodes. These batteries have low internal resistance, high charge and discharge rates are possible, typically discharge rates of up to 10C for short periods, flat discharge characteristics but drop rapidly at the end of the cycle, tolerate deep discharges, and have a wide temperature range (up to 70 degrees Celsius). However, they are susceptible to memory effect, prone to damage due to overcharging, and cadmium is an environmental concern.
Nickel-metal hydride batteries (NiMH) are a type of secondary electrochemical battery that uses a hydrogen-absorbing alloy for the negative electrode instead of cadmium. As with NiCd batteries, the positive electrode is nickel oxyhydroxide. A NiMH battery can have two to three times the capacity of an equivalent-sized nickel-cadmium battery. However, compared to lithium-ion batteries, the volumetric energy density is lower and the self-discharge is higher. The high energy density is 50 percent better than NiCd batteries but about 60 percent of lithium-ion batteries, it has low internal impedance, a typical cycle life of 3000 cycles and can be deep-cycled. These batteries tolerate overcharge and overdischarge conditions, have a flat discharge characteristic but degrade rapidly at the end of the cycle, and have a wide operating temperature range. It is environmentally friendly (does not contain cadmium, mercury, or lead) compared to equivalent-sized NiCd batteries. In contrast, it has a high self-discharge rate and deteriorates during long-term storage.
Lead acid batteries are a rechargeable battery that works by using lead and sulfuric acid. The lead is immersed in sulfuric acid to allow a controlled chemical reaction. This chemical reaction causes the battery to produce electricity. This reaction is then reversed to recharge the battery. Lithium-ion batteries are generally at least 95 percent efficient, while lead acid batteries are around 80-85 percent efficient. This is important because it allows the battery to charge faster and have a higher effective battery capacity. However, the amount of usable energy compared to the stored energy is much lower than other batteries. It also has a limited cycle life, some charging problems, inefficient energy usage, and is large and bulky. Most importantly, lead creates serious environmental problems.
Among the numerous testing, measurement, analysis and evaluation studies that our organization has provided for businesses in various sectors, it also provides testing services defined in the “RTCA DO-293 Minimum operating performance standards for nickel-cadmium, nickel metal-hydride and lead acid batteries” standard with its trained and expert staff and advanced technological equipment.
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