Lithium battery test equipment solution, with laboratory circuit, application notes

Test - lowercase jpg

Kaixin micro test

Test probe P100-M3

Summary:

Lithium batteries have many advantages over other chemical batteries. For example, a lithium battery is lighter, has no memory effect, and has a slower self-discharge rate than a nickel-hydrogen battery or a nickel-cadmium battery. Lithium batteries have been widely used as rechargeable batteries for modern electronic devices such as smartphones and notebook computers. Due to clean energy requirements, lithium batteries have recently become popular in high-power applications such as electric vehicles, power tools and energy storage.

With the rapid growth of lithium batteries, the test equipment used in the manufacturing process has also become very important. The typical functions of the lithium battery test equipment are as follows

• Formation and classification: After the battery unit is assembled, each unit must undergo at least one precisely controlled charge and discharge cycle to activate the working material and convert it into a usable form. Battery vendors can also use this process to divide battery cells into different performance groups for sale based on optional specifications, which is called "grading."
• Cycling and feature testing: Cycling refers to multiple charging and discharging of battery cells and battery packs to perform life and reliability tests. The feature refers to the detailed measurement of the technical characteristics of the battery. In general, both tests take a long time, usually more than one day, and only some of the selected battery samples are tested in the laboratory.
• Functional Testing: To ensure that each battery cell and battery pack is functioning properly before delivery to the end customer, each battery must be functionally tested after manufacture. To reduce test time, functional testing is a simplified test that includes only the necessary items.

Analog Devices Solutions

The value proposition of the ADI solution:

• A one-stop supplier offering the broadest portfolio of products required for lithium battery test equipment signal chains, such as amplifiers, ADCs, DACs, isolators and processors.
• ADI product compatibility supports porting designs across multiple platforms, for example, pin-compatible level-setting DACs offer a variety of different resolutions.
• On-chip integration optimizes signal chain performance and minimizes board space and BOM cost. For example, instrumentation amplifiers and differential amplifiers integrate high-performance op amps and resistors for excellent common-mode rejection ratio (CMRR) and drift performance.
• A wealth of design resources, including easy-to-use simulation tools (ADIsimPower?, DiffAmpCalc?), discussion forums in the ADI Chinese Technology Forum, fully populated evaluation boards, and more.
• Circuits from the Lab? Lab circuits are tested reference circuits that help accelerate design while simplifying system integration to help and solve today's analog and mixed-signal design challenges. Web-based design tools optimize the performance of custom designs. At the end of the article, some examples of network-based design are also provided.

System Block Diagram

A high-level overview of the lithium battery test system is shown below.

The details of the linear/switch charge and discharge control unit are shown below.

The details of power generation and management are shown below.

Laboratory circuit / demonstration design

• CN0197: Lithium-Ion Battery Pack Monitor with Integrated Signal and Power Supply Isolation
• CN0146: Using the Quad Single-Pole Single-Throw Switch ADG1611 and Instrumentation Amplifier
• AD620 implements low cost programmable gain instrumentation amplifier circuit
• CN0218:500 V Common Mode Voltage and Current Monitor
• CN0190: Multi-Voltage, High-Efficiency, 25 W Universal Power Module with 6 V to 14 V Input Robust Performance
• CN0180: Precision Low Power Single Supply Fully Integrated Differential ADC Driver for Industrial Grade Signals

Technical Article / Application Notes

• Differential amplifier vs current sense amplifier. Analog Dialogue Volume 42, Issue 01, January 2008 (High-end Current Detection)
• Isolation of high voltage battery monitoring in transportation applications. Analog Dialogue Volume 43, October 2009
• Switch and multiplexer design considerations in harsh environments