Bidirectional Power Supplies Put New Batteries to the Test

Sept. 15, 2023

Testing a high-voltage battery? Building a battery-powered IoT device? Check out this installment of Products of the Week for the latest battery test systems to hit the market.

James Morra

Related To: Electronic Design

Bidirectional Power Supplies Pack a Punch for Testing

For any battery-powered system to perform at its best, the battery inside needs to be on its best behavior. Because of the risks posed when they malfunction or even fail, batteries must undergo rigorous testing at every step of their lifecycle—ranging from development and testing to the production plant to the battery’s second life and even recycling and reuse—to make sure they will meet the requirements of the real world.

Today, battery test equipment tends to be based on bidirectional power supplies that unite a DC power supply to charge the battery being tested, along with electronic loads that can discharge a battery to understand how it will degrade over time through constant use. Using hardware and software to simulate batteries is becoming standard operating procedure. But it can pose a challenge to reliably replicate the potential sources of trouble.

The latest battery test systems are being upgraded to give engineers a more precise and accurate way of simulating the behavior of the battery cell, module, or pack under varying charging or discharging conditions.

They enable you to control a battery’s voltage, current, and power output and simulate the different conditions a battery may encounter in the field. This type of testing is useful for evaluating a battery’s capacity, efficiency, self-discharge rates, and many other characteristics, as well as identifying potential faults and dialing in battery design. Typically, battery cyclers carry out constant current/constant voltage (CC-CV), constant resistance (CR), constant power (CP), fast pulse, voltage and current ramp, and other tests to put a battery through its paces.

The storage capacity of batteries continues to rise, specifically in EVs, which rely on electrical power for every aspect of their operation. As a result, battery cyclers with high power capabilities are increasingly in demand, said Eric Turner, managing director at Elektro-Automatik.

Voltage levels are increasing, too. While 400- and 800-V battery packs are becoming the standard in EVs, the high-voltage batteries being strapped to the electric grid for long-term storage are typically tested at 1500-V.

It’s necessary to not only test the battery in isolation, but also to evaluate its performance in the system being powered by that battery. Instead of risking costly physical batteries, engineers can use battery emulators to test the building blocks of the system where the battery will reside.

By pretending an actual battery is present, engineers can test out components such as a powertrain, onboard charger (OBC), and DC-DC converter in EVs in a safer, more repeatable environment, while reducing the impact of variables such as temperature dependency or human errors in the early stages of testing, according to NI. Besides being potentially hazardous, EV batteries are very expensive, and no one wants to render one useless.

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The world is working to build batteries that are safer, charge faster, and store more energy, installing them into everything from electric vehicles (EVs) to new types of IoT devices. Consequently, testing is becoming an even more important part of the development process. The insights stemming from battery testing can help identify problems that negatively impact battery safety, reliability, quality, storage capacity, and even charging rates over time.

As a result, everyone from NI (formerly National Instruments) to Elektro-Automatik to other industry players are introducing better battery test systems that promise to save space, cost, and time while offering more flexibility.

To stay a step ahead of the technological shifts occurring inside batteries, they’re rolling out new generations of battery test systems that can handle higher power levels along with wider voltages and currents. And these are rarely one-dimensional systems: They can become power supplies or electronic loads for battery cycling, and they frequently also act as battery emulators in cases where you may not want to risk a real-world battery.

Besides handling higher power levels, voltages, and currents, they are also being upgraded with new control and measurement hardware to gauge the voltage, current, and temperature of a battery and more accurately diagnose the internal operations of battery cells, modules, and packs. Software, too, is increasingly part of the package to provide connectivity to other test equipment, manage massive amounts of data, and analyze it all.

In this gallery, we'll explore some of the technical issues facing engineers when it comes to batteries and review some of the latest battery test systems that they can use to overcome these challenges:

Check out the previous Products of the Week gallery here.

You can also visit the Products of the Week archives here.

About the Author

James Morra | Senior Editor

James Morra is a senior editor for Electronic Design, covering the semiconductor industry and new technology trends, with a focus on power management. He also reports on the business behind electrical engineering, including the electronics supply chain. He joined Electronic Design in 2015 and is based in Chicago, Illinois.