Battery Intelligence™ Incorporated Developing Robust Fuzzy Logic Methods to Accurately Fuel Gauge Batteries

Formed in 2001, Battery Intelligence™ Incorporated (“BII”) is a spin-off of US Nanocorp, Inc., a Farmington, Connecticut-based technology company developing nanomaterials for batteries and fuel cells as well as fuzzy logic-based methods for the estimation of State-of-Charge (“SOC”) and State-of-Health (“SOH”).

Government contracts from US SOCOM, DARPA, the US Army, the US Navy, and the National Institutes of Health have funded the development of prototype hand held meters for battery management in a wide variety of chemistries in both primary and secondary cells, including Pb-acid, Li-ion, and Ni-MH. In fuel cells, the PEM system has been evaluated with regard to SOH. Algorithms to implement real-time corrections to performance decay trends on small fuel cell stacks in the 10-watt range were successful.

The fuzzy logic approach treats the battery as a black box and does not attempt to model the complex battery systems. The approach is elegant and simple, yet highly accurate and relies on a minimal data set. The BII Fuzzy logic method accurately determines SOC and SOH from coulomb counting or the impedance measurement of batteries. The Fuzzy Logic method is code efficient and will determine the SOC of rechargeable and primary cells, and the SOH of rechargeable cells. Determining the SOC of a primary cell using the Fuzzy Logic method is attractive because it does not result in any discharge of the cell.

BII's most recent generation instrumentation is a hand held SOC and SOH monitoring device for Pb/Acid batteries. This design measures impedance and phase shift to accurately determine SOC and SOH using a Fuzzy Logic model specifically designed for Pb/Acid batteries. At the core of this device is a Motorola 68HC12 microcontroller. This processor allows precise signal generation, high resolution acquisition, and fast data processing due to a built-in Fuzzy Logic instruction set. The use of a microprocessor-based system also allows for data logging and software updates to provide battery specific customization. Through the design of precise current regulation circuitry and automatic impedance range selection, this meter has a large testing range. The current model is capable of measuring SOC and SOH for batteries between 2 and 14 volts and between <1 and >200 Ah of capacity. The device is hand held and portable, while still providing a high amperage test current for enhanced measurement accuracy. It is designed to be operated from either wall power or a high capacity battery.

This implementation has an accuracy of +/- 5% over a variety of cells from different production lots. Additionally, BII has developed an application specific integrated circuit (“ASIC”) with a Fuzzy Logic algorithm as a drop-in solution to determining SOC.

Battery Intelligence Incorporated
74 Batterson Park Rd.
Farmington, CT 06032

Tel: 860.678.7561
Fax: 860.678.7569
Contact: David Reisner, Ph.D.
Email: dreisner@usnanocorp.com
Web:  www.batteryintelligence.com

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