Smart Batteries: the Importance of the Power Source

Accutronics describes the battery challenges in test and instrumentation equipment. The power source may not always be the first thing design engineers think of, but when there is a loss of power, all results are lost

High quality components, batteries included, are essential to provide consistent and accurate measurements. In these pages Rob Brown, marketing executive at professional battery manufacturer Accutronics, explains the role batteries play in achieving reliable instrumentation, and the challenges design engineers should consider.

An application example from the space

A few weeks after the 4.7 billion dollars launch of the Hubble Space Telescope in 1990, an error became apparent to the NASA team: the images returned by the telescope were not as sharp as had been intended. This was caused by a problem with the telescope’s optic system, because the outer perimeter of the primary mirror was 2,200 nanometres too flat. An investigation into how this occurred pointed to a reflective null corrector, which is a device used to test and properly shape non-spherical mirrors. This device had been assembled specifically for the telescope’s construction but had been done so incorrectly, with a lens 1.3 mm out of position. The slight difference had a significant impact on the usefulness of the telescope, until it was balanced out three years later. This led to a series of expensive launches to fit and replace instrumentation over the subsequent years. Although most instrumentation applications tend to be closer, the Hubble Space Telescope highlights how even slight deviations in measurement can have significant consequences.

Application and operative environment: how to choose the power source

Design engineers working on test, measurement and instrumentation devices aim to guarantee precision by specifying high quality components, and ensuring designs are fit for purpose and functional. One of these components is the power source. Power may not always be the first thing design engineers think of. Yet if there was to be a sudden loss of power, either due to a mains electrical fault or a battery failure, then all results would be lost. Likewise, dips in energy delivered to a digital device can affect the recorded measurements. When choosing the optimum power source, it is important to consider the device’s intended application and the environment it will operate in. If the device is manned, portable or in regular use then a secondary (rechargeable) battery may be best suited because it can communicate information to the user, such as battery health and state-of-charge. Alternatively, if the device is used in a location where natural energy is available from the sun or wind, it makes sense to harness that power. For example, a weather station could use a secondary (rechargeable) battery that is charged by solar or wind power and, therefore, can operate for many years without the need for human intervention. Whilst some devices have the luxury of being able to scavenge renewable energy, others like ocean-bottom seismometers can be set for long periods in remote locations where they have limited access to power and cannot be recharged or replaced. In these environments, primary (non-rechargeable) batteries with low self-discharge rates are essential to provide power across a period spanning several weeks or months. The batteries will also need to be ruggedised to withstand high pressures and shock.

Custom solutions to meet a unique application challenges

Although each of the above applications are varied and require different forms of power, what they have in common is the need for reliable, high performance batteries. If the batteries were suddenly to fail then there would be no readings available, which would hinder the research or monitoring purposes of the devices. One of the core challenges faced by batteries in test and measurement devices is that there is no single set of typical needs. A portable vehicle emissions testing device will face very different operating environments compared to a seismometer. It’s for this reason that when Accutronics works with design engineers on test and instrumentation projects, it is often to develop these solutions that meet an application’s unique challenges. Accutronics counts on years of experience developing and manufacturing these solutions to meet the complex requirements of many test environments. The company’s Accupro service builds on this expertise to offer a custom battery or charger that meets individual application requirements and product development timeline.