ENG Systems, Sanyo Develop Better Batteries by Using LabVIEW

Author(s):
Zoltan Vanyi - ENG Systems Hungary Ltd

Industry:
Consumer Goods

Products:
LabVIEW

The Challenge:
Developing a flexible battery test system capable of keeping pace with changing product requirements.

The Solution:
Using NI LabVIEW software to design a precise tester that is compatible with a wide range of product offerings.

SANYO Corporation has produced quality batteries for years. However, to keep pace with the constant evolution of battery technology, the company needed to develop special measuring and testing machines. ENG Systems in Hungary helped Sanyo meet this challenge by using LabVIEW to design a new test system. We required a system that offered faster and more precise testing to maintain our ability to produce competitive products. Our goal was to develop a tester that would be compatible with most batteries up to 24 V.

The Introduction of Testing Equipment

Based on the original test system and according to previous similar experiences, we collected parameters as well as measuring and programming methods and created a solution capable of testing many kinds of batteries. The measuring apparatus programs comprehensive tests, executes these tests, and measures the built-in safety circuits. We can check different types of batteries thanks to the modular hardware structure of the tester and its flexible software. The measuring system is able to test several defined batteries up to 24 V size. ENG Systems developed the major parts of the hardware, including special elements such as programmable charger and discharger current sources, precise current monitoring shunts, and programmable isolated reference power supplies. These components are built as modules into the switching matrix and controller circuit. The only exception is the AC mΩ meter device by HIOKI, which measures the source impedance and voltage of the battery. This instrument is built into the tester frame and connected to the controller PC with an RS232 interface. The hardware also contains a serial communication manager; precision programmable voltage references; necessary switching matrix and connection nets; DC current sources; and loads for testing, charging, and discharging.

The tester checks the following functions in the battery units:

• Terminal voltage and internal impedance
• Protector circuits
• Disconnection of electric charge in case of cell overflow
• Electric serial number checking, logging, and programming
• Cell-line voltage balancing and logging of the calibration-correcting factors
• Overload off-switching protection in case of low cells

There are several advantages to this system including a universal data-logging structure for any type of battery, simplification of the type-exchanging process with automatic product identification, and product-mixing detection. In addition, we can digitally program the power pack and references, which allows for new procedure applications without exchanging hardware. Also, the time-saving tests increase the efficiency.

Hardware

The controlling PC and measuring system are built into two separated electromagnetic compatibility (EMC)-protected device houses. The measuring apparatus includes a HIOKI 3560 AC impedance-measuring HiTESTER. The HiTESTER measures the inner impedance independently of the DC terminal voltage. Pairing the parametric generator and phantom load with seven galvanic independent reference generators produces the precise signals to check the charging and discharging of the batteries. The central program controls the generators, multiplexers, and measurements through a USB connection using a specified metalanguage. A PC controls the series data ports of the battery, the HIOKI 3650, and the USB host to impedance-measuring apparatus.

Joint sockets help the physical connection between the tester and batteries. Although some sockets are pneumatic, intervalve gear circuits are not required because the tester delivers the 24 VDC control signals to the pneumatic valves.

Software

We control the tester with a measurement program developed using LabVIEW. We can modify or improve the program structure at anytime for new testing. We store the parameters in an external database, so we do not need to modify the shell program when changing the process. We can edit the databases with Microsoft Excel or in text format. The program detects type exchanging and, after user approval, automatically changes the program. With the test program’s accelerating function, we can disconnect or retest the failed batteries without taking unnecessary steps.

Using LabVIEW, our design team was able to create a front panel that is logical, easy to handle, and displays all necessary information. The front panel displays test results with a color-coded scheme. When the program detects a failed battery, the results appear in red, and the user is warned to separate the failed battery. The results are saved to log files in chronological order according to type. Users can process the log files with Excel or text editor programs for analyzing or SPC process advocating.

Author Information:
For more information on this Case Study, contact:
Zoltan Vanyi
ENG Systems Hungary Ltd
Hungary
Tel: +36-1-240 63 83
zoltan.vanyi@eng.hu

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