Technical Papers

Capattery Double-Layer Capacitor Life Performance
presented at the 11th Capacitor & Resistor Technology Symposium, 1991
John R. Miller, David A Evans, Nancy H. Clark, W.E. Baca, and Thomas B. Barker


Double layer capacitors (DLCs) have received increased use in computer memory backup applications for consumer products during the past ten years. Their extraordinarily high capaci tance density along with their maintenance-free operation makes them particularly suited for these products. These same features also make DLCs very attractive in military type applications. Unfortunately, lifetime performance data has not been reported in the literature for any DLC component.

Our objective in this study was to investigate the effects that voltage and temperature have on the properties and performance of single and series connected DLCs as a function of time.

Evans model RE110474, 0.47 farad, 11.0 volt Capatteries were evaluated. These components have a tantalum package, use welded construc tion, and contain a glass-to-metal seal, all incorpo rated to circumvent the typical DLC failure modes of electrolyte loss and container corrosion.

A five-level, two-factor "Central Composite Design" was used in the study. Single and series connected Capatteries rated at 85°C, 11.0 volts operation were subjected to test temperatures between 25 and 95°C, and voltages between 0 and 12.9 volts (9 test conditions). Measured responses included capacitance, equivalent series resistance, and discharge time. Data were analyzed using a regression analysis to obtain response functions relating DLC properties to their voltage, tempera ture, and test time history. These results are de scribed and should aid system and component engineers in using DLCs in critical applications.

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