Safe and reproducible short-circuit testing of battery systems

A short circuit is one of the most critical fault conditions in a battery system. Yet during development and validation, this is precisely the condition that needs to be created in a controlled manner. The objective is to investigate both the response of the battery management system and safety devices and the behavior of individual cells, modules or complete battery packs under short-circuit conditions.

High currents must be switched safely, fast transient events must be captured reliably, and the short-circuit path must be designed to minimize the influence of the test setup on the measurement results. The battery short-circuit tester from SMART TESTSOLUTIONS has a modular design and can be configured for different devices under test, measurement tasks and test environments.

Different test objectives require different setups

One important application is the validation of safety devices. This involves verifying whether components such as high-voltage contactors, fuses or pyrotechnic disconnects respond correctly in the event of a fault and interrupt the current path.

What matters is not only whether the circuit is interrupted, but also the timing of the response: When does the safety device react, and how do current and voltage change during the event?

The behavior of the battery system itself can also be investigated. For this purpose, protection mechanisms can be deliberately bypassed to test a cell, module or complete battery pack under short-circuit conditions. Parameters such as peak currents, discharge behavior and thermal behavior can be analyzed.

The design of the short-circuit test system therefore depends on the specific test objective.

The test setup influences the short-circuit current

During a short-circuit test, the resulting current is not determined by the battery alone. Cables, contact points, switching elements and measurement resistors are also part of the current path.

Additional cable and contact resistance can affect the short-circuit current and therefore influence the test result. For this reason, the electrical setup must be considered as a complete system.

Positioning the short-circuit switch as close as possible to the device under test keeps the high-current cables short and reduces additional influences from the test setup. The exact design of the current path depends on the specific test requirements.

The key is to establish a defined and reproducible test setup that accurately represents the intended fault condition.

Switching high currents and capturing fast events

The SMART TESTSOLUTIONS short-circuit switch is designed for system voltages of up to 1,000 V and short-duration currents of up to 40,000 A.

For test evaluation, the maximum current is only one aspect. The current profile over time and its interaction with voltage and temperature are equally important. The measurement system can acquire these parameters at up to 1 MSample per channel. The number, measurement range and type of measurement channels can be configured according to the specific test task.

This makes it possible to determine when the short circuit is initiated, how the current and battery voltage develop, and at what point a safety device responds.

Short high-current paths and protected measurement equipment

The short-circuit switch and measurement equipment can be installed separately.

The switch is positioned as close as possible to the device under test to keep high-current cables short, while the measurement and control equipment can be located outside the immediate hazard area.

This is particularly relevant for tests where a severe thermal reaction of the battery system cannot be ruled out. Depending on the application, the short-circuit switch can, for example, be operated inside a safety container or climatic chamber.

Modular design for different test tasks

Whether testing an individual cell, a module, a vehicle battery or a stationary battery storage system, voltage, current, measurement requirements and test environments vary depending on the application.

The short-circuit switch, measurement and control equipment, and additional components are therefore configured according to the specific test task. Existing measurement equipment can also be integrated, as can additional resistances or inductances.

Integration into existing test environments is also possible. The short-circuit tester can be operated via Ethernet and integrated into an existing emergency-stop circuit.

Instead of adapting the test to a rigid test bench, the test setup is configured around the actual test requirements.

Safety must be part of the test setup

A short-circuit test deliberately puts the device under test into a critical operating condition. Under severe thermal stress, thermal runaway may occur, potentially resulting in high temperatures, smoke and fire or, in extreme cases, an explosion.

The short-circuit test system must therefore be integrated into the safety concept of the respective test environment. The required measures depend on the device under test, the test objective and the existing infrastructure.

The test task determines the test system

The starting point is therefore not simply the question of how much current a tester can switch. First, the actual test requirements need to be defined:

What needs to be tested: a cell, module, battery pack or safety device?
Which fault condition needs to be reproduced?
Which current, voltage and temperature profiles need to be captured?
How should the current path be designed?
What safety infrastructure is already available?
What measurement and control equipment is required?
Which standard applies to the test?

Based on these requirements, the short-circuit switch, measurement equipment, connection to the device under test and safety integration can be configured to match the specific test task.

Only a defined test setup turns an intentionally induced short circuit into a reproducible test.