Power Electronics

Patents Address Battery Charging and Gauging Challenges

Nexergy, a manufacturer of battery packs and chargers, has solved complex battery fuel gauge and charging issues with two circuits now awaiting patent approval. One patent application is for a robust discharge circuit that can be applied to the calibration of fuel gauges. The other is for a buttonless battery charger interface that can be used in designs in which a switch is not practical and in designs for harsh environments. The inventor behind both applications is Randolph (Randy) A. Ibrahim, Nexergy's vice president of technology.

In battery charging and conditioning systems, discharge circuits may be used to completely discharge a battery before beginning a charging cycle. In battery calibration systems, discharge circuits may be used to determine the characteristics of batteries. For battery types such as lithium ion (Li-ion), determining the characteristics of the battery under load conditions may assist in determining battery condition as it ages. Additionally, calibration systems produce information that allows predicting performance of the battery over its service life.

The discharge circuit for which Nexergy seeks its patent is designed to address the challenges of battery calibration in environments where consistent power is often unavailable, such as in military vehicles and ambulances.

"Normally, when you lose power, you have to go through a whole new cycle in order to calibrate," Ibrahim said. "And if you get continuous interruptions of power, you'll never get a clean calibration especially on the older coulomb-counter fuel gauges. This unique circuit addresses this challenge by feeding power back on itself during moments of power interruptions. In fact, during a calibration cycle, the user could unplug the charger from the power source, and sequential discharging lights and charge status indicators will remain operating when power is automatically diverted from the battery being discharge to the charger/discharger circuitry to keep it alive and operating. The patent covers a multitude of methods of accomplishing this functionality."

The patent application for the buttonless battery charger interface applies a fresh approach to the issue of controls attached to the interfaces of battery chargers. Harsh environmental factors particularly cause the most simple control mechanism to fail under normal and heavy use. This battery-charging invention applies "a plurality of modes" for charging a battery. The method of control is mainly time-based with debouncing circuitry included to minimize false commands from being issued.

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