Source Measure Units (SMUs) and Battery Testing

The proliferation of lithium-ion batteries, with devices such as laptops, tablets and mobile phones all deriving power from them, has made battery testing a key area of research for every battery pack manufacturer. Quality and length of discharge and recharge, as well as the overall cost of manufacturing cells, matter hugely both in the consumer market and in batteries made for industrial use.

Production testing in industry can be a difficult proposition when using a multitude of pieces of equipment, such as an ammeter, voltmeter and a programmable power supply, which is not conducive to producing accurate reflections of a battery’s performance. A source measure unit (SMU) simplifies the testing process by offering voltage, current sourcing and useful measurement ranges without the need for tricky synchronisation of several pieces of equipment.

By setting a custom current rate, a user can recharge the device under test (DUT) to a desired level or test the battery’s discharge and measure voltage by dissipating power at a controlled rate. An SMU offers more control over the testing process than a typical set-up while also improving simplicity and decreasing costs.

The increased control and reliability offered by an SMU over a rack of testing equipment means greater precision; two characteristics of precise tests are those of accuracy and sensitivity. In testing terms, accuracy refers to the maximum margin for error allowed by a given piece of testing apparatus. SMUs typically offer an error margin of less than 0.1 per cent, making them among the most accurate testing devices available to battery pack manufacturers. Sensitivity refers to the smallest change that can be detected or enacted by a device. SMUs offer a large range of settings for both sourcing charge and reading current and voltage of a DUT.

For a battery pack manufacturer who values rigorous testing methods, SMUs have much to offer. As well as a greater level of precision in battery testing than that afforded by a multitude of equipment, SMUs are ideal for testing semiconductor materials. The combination of power, accuracy and speed in both sourcing and measuring in a single piece of equipment makes the use of SMUs a simple and effective alternative to traditional testing methods.