How Test Equipment Is Evolving to Keep Up with EV Batteries

Given the higher energy present in batteries today, test systems have had to change to carefully monitor temperature as well as charging and discharging voltage and current.

April 1, 2025

People who love EV technology are living in exciting times. Vehicle batteries continue to grow in energy capacity, and new battery chemistries like lithiumiron phosphate battery are coming, bringing even more change. As vehicle batteries have evolved, so has the equipment needed to test them.

In a general sense, battery test systems can work with any type of battery. The systems source and sink power, simulate drive profiles, and measure volts, amperes, and resistance. Dive deeper, and there are real differences in the requirements as EV batteries have evolved.

As batteries are electrochemical in nature, they give energy quickly and change state quickly. The test equipment needs to be at least as fast as the battery in terms of sourcing, sinking, and ultimately simulating drive profiles. The slower the test equipment is in terms of sourcing and sinking current and changing voltage, the less accurate the battery testing will become.

Evolving Battery Testing Requirements

It used to be the case that the equipment used for battery emulation could not keep up as well. A test system designed using programmable DC power supplies with insulated-gate bipolar transistors (IGBTs) could ramp power up or down only so fast, as it was limited in its switching speed and, therefore, could not accurately recreate the performance of a real battery.

Starting in the 2010s, bi-directional DC power sources became available that use silicon-carbide-based (SiC) power MOSFETs. These devices switch much faster with current rise and fall times on the order of 1-5 ms, which is an order of magnitude greater than that of an IGBT typically. More advanced SiC-based test systems offer current rise and fall times of less than 1 ms, with the latest systems as fast as 500 μs, which more closely matches the speed of lithium batteries and other common chemistries.

Today’s SiC-based test instruments have caught up to the evolving battery test requirements, but in the future, test systems may use gallium nitride (GaN) based power semiconductor devices. Compared to SiC, GaN has superior properties for electron transport, enabling faster switching speeds that may potentially lead to even better test system performance. Fabricating GaN semiconductor devices requires specialized processes and equipment. As manufacturers learn how to improve fabrication, GaN devices will become more available and affordable for inclusion in battery test systems.

In their quest to extend vehicle range by increasing energy storage capacity, engineers are designing batteries with an increasing number of cells consisting of more cell strings and more strings in parallel. In addition, to lighten vehicle components and improve charging performance, the voltage of battery packs has increased. Early EV batteries operated at around 400V, while newer vehicles operate at around 800V.

Programmable power supplies test more than EV batteries. (Image: AMETEK Programmable Power)

Moving Toward an Integrated Test System

These two battery design trends are changing the test system requirements. The systems need to source and sink higher and higher levels of current and voltage. This has led to an increased focus on integrating safety devices like safety interlocks, galvanic isolation, and overvoltage protection.

Additionally, the entire battery test system is more integrated. It used to be that a test system would be made up of individual components: a source, a load, a scope, a DMM, and third-party or homegrown software to tie it all together. Now, one test instrument can simulate a vehicle driving and measure the battery’s reaction at the same time. More than just a bidirectional power supply, today’s systems are specialized for EV battery manufacturing, including the required safety to prevent catastrophic failures.

Because of the higher levels of power, test equipment manufacturers have had to develop battery test systems that are energy efficient, with most new systems being regenerative. Instead of releasing the power drawn off the electronic load as heat, the system redirects the power back to the grid or uses it to charge a second battery under test. In a production test application, the cost of buying electricity from the energy supplier quickly adds up. Over time, the energy savings cover the higher cost of a regenerative battery test system. What’s more, because the energy is returned to the grid and not released as heat, the facility cost of air conditioning is significantly reduced.

A standard EPA UDDS electric vehicle drive cycle test. (Image: United States Environmental Protection Agency)

In production battery test, the total amount of power involved is huge, in the megawatts potentially. As a result, the test system may occupy multiple test racks and consume precious space on the production floor. Test systems are moving to SiC-technology that increases the power density to reduce this size requirement and allow users to better maximize their floor space.

Given the higher energy present in batteries today, test systems have had to evolve to carefully monitor temperature as well as charging and discharging voltage and current. If a discharge cycle brings the battery charge below 5 percent, then the battery may be damaged. If a charge cycle keeps charging beyond the battery’s rated capacity, then a dangerous fire could occur.

Now, all of those components are getting rolled into one unified instrument. This has been necessary because of the higher power involved and the difficulty of integrating multiple racks of equipment. An engineering manager can assume that a turn-key battery test system has been properly designed for speed and safety.

This system approach has the advantage of being easier to use and maintain as there are fewer components to integrate and fewer vendors.

An example of a programmable DC power supply. The Mi-BEAM is a bi-directional DC source using SiC technology for fast voltage and current response transients. (Image: AMETEK Programmable Power)

One of the things that engineers sometimes overlook is the software. It used to be common for battery test systems and battery emulators to require an expert programmer to configure the tests. To change a test profile meant bringing in that programmer and took days and weeks. Now, it is common for included software to be easy to use; an engineer who is not an expert programmer can use visual dropdowns to configure and adapt tests from a supplied library.

Relying on Emulators

In an EV, the battery is not the only system that needs testing. The battery drives all the systems of the vehicle — motor, inverters, converters, EVSEs, etc. The old way of testing these systems was to hook them up to the battery. Because batteries need time to recharge, time to rest before discharge, and time to rest before charging, a full test cycle can take days. In contrast, a battery emulator can cut the test time to a few hours.

For EV manufacturers, emulators are far more practical than dedicating a battery for each system test and trying to produce vehicles at scale. Battery packs can weigh thousands of pounds, take up valuable floor space, require maintenance, and are potentially explosive. Battery emulators are the modern way to test.

Whatever technology is employed in the future, it is clear that battery test systems will continue to adapt to keep pace with changes in EV battery technology and production. Ensuring that you choose a future proof, scalable, and capable bi-directional DC source is critical in planning for testing success today and tomorrow.

This article was written Ben Jackson, Director, Product Line Management, AMETEK Programmable Power (San Diego, CA). For more information, visit here .