Episode 4 Column
Episodes 4–6 focus on electronic loads, whose primary function is to consume electricity. Just like the withstanding voltage testers mentioned earlier, electronic loads are not very common testing devices. It’s because most engineers in electronics-related fields are primarily focused on creating circuits that consume electricity, so they rarely have the opportunity to use an electronic load. Even within the electrical and electronics fields, engineers who use electronic loads in their daily work are a minority. For most people outside the field, those devices are probably completely unknown. You certainly won’t find one at your local electronics shop, and I myself had never even heard of them until I joined Kikusui Electronics.
Although nowadays electronic loads are finding their way into more applications, their use is still relatively limited. A good example is the development and manufacturing of DC power supplies. Considered a central component of electrical equipment, DC power supplies went through a significant technological breakthrough in the 1960s, when NASA developed the switching power supply. To meet the demand for compact, lightweight, and efficient electronic equipment for rockets (see “Introduction to DC Stabilized Power Supplies”), a new circuit design was developed. Since the 1970s, this design has been widely adopted in communication devices and home appliances. As a result, manufacturers specializing in developing and producing embedded power supplies prospered, and electronic loads became widely used for output testing of switching power supplies. Demand for electronic loads (production volume and price) increased, but until the 1990s, power supply manufacturers remained the main users. However, a major change came with the technological innovation of secondary batteries (rechargeable batteries).
Beginning in the late 1980s, the growing demand for mobile communications (cell phones), notebook computers, and portable audio devices led to the development of new types of secondary batteries. Compact, high-capacity, and high-performance nickel-metal hydride (NiMH) and lithium-ion batteries replaced nickel-cadmium (NiCd) batteries. To evaluate the performance (discharge characteristic analysis) of these next-generation secondary batteries, a new type of equipment emerged: the electronic load. When testing secondary batteries, you need to account for many different types of load circuits (circuits that consume battery power). However, it’s simply impossible to gather and test every possible real-world scenario. Electronic loads are, therefore, valuable instruments for simulating these various conditions. Furthermore, unlike switching power supply testing, secondary battery testing is required not only by battery manufacturers but also by device manufacturers, which has likely contributed to the broader adoption of electronic loads.
In Episode 4, Minami wonders whether there’s a device that can drain electricity. Professionals in the electrical field might think this is common knowledge, but in reality, electronic loads are still not widely known. In the manga, there’s a scene where a robot wags its tail to drain a battery. You might think this is an incredibly inefficient method, but situations like this actually happen. Even at EV testing sites, known for their cutting-edge technology, people go through painstaking efforts to quickly discharge onboard batteries. They drive endlessly around a test track, leave the headlights on, or run the wipers overnight.
