Purchasing thoughts on portable power

Challenging environments require a rugged battery holder solution, particularly in portable applications where shock and vibration prevail. President of Memory Protection Devices, Tom Blaha, explains what to look out for.

Whereas the choice of battery holder is often cost-driven for consumer electronics, industrial equipment requires greater forethought to specify the ideal solution based on the requirements of the operating environment. This can vary significantly, depending on whether the application is stationary or portable.

For example, a data logger located on an 18-wheel tractor trailer must offer protection against the battery becoming dislodged due to continuous shock and vibration. Extremely corrosive environments also challenge product reliability. The battery, as well as the entire electronic assembly, would therefore need to be shielded from corrosive gases and road salt. Overall, the ideal power supply solution must feature a low failure rate, as measured in mean times between failures. This metric helps govern the frequency of required system maintenance and inspections.

Corrosive environments
Despite being stationary, some products may still require a rugged solution. Mine safety equipment utilizes stationary gas detectors strategically placed at the lowest point of the mine to monitor the presence of potentially deadly gases. These devices must withstand extreme humidity and corrosive gases, as per ASTM B117. These salt spray tests reproduce a corrosive attack on platings and assemblies in order to evaluate the protective finish.

Battery-powered devices are also utilized throughout the petroleum industry to remotely monitor pumps and pipelines. Equipment used here must withstand extreme temperatures, as well as salt spray and contact wear tests. To ensure this, manufacturers simulate fretting, where repeated surface motion under load can cause mechanical wear and material transfer to contact surfaces.

Putting safety first
Similar effects can be experienced in portable medical devices such as glucose meters, thermometers, or wearable drug delivery systems. These devices must be designed according to FDA-21 regulations, taking into account human factors such as age and functional capabilities that could impact the safety and efficacy of the device.

Portable medical devices must therefore be highly durable, meet rigorous requirements for MTBF, drop testing, salt spray, thermal and contact wear testing. Certain medical devices also need to undergo routine sterilization, preferably without having to remove either the battery or battery holder. All sterilization processes involve extreme environments, including: autoclave steam sterilization at 1 to 3.5 atmospheres and 120 to 150°F temperatures; chemical sterilization procedures involving corrosive compounds; and radioactive sterilization using gamma rays or electronic beams.

With these factors in mind, due diligence is required when designing a battery-operated power supply for use in extreme environments. Engineers and procurement professionals must work together to ensure that the device meets and exceeds customer expectations and delivers rugged and reliable performance that increases product operational life to maximize the total return on investment. Paying a few cents more to develop a ruggedized product also helps avoid product failure that can ultimately prove costly to your company’s reputation and bottom line.