An innovative battery charger for safe charging of NiMH/NiCd batteries

This paper presents the design and development of a novel battery charger for simultaneous charging of two NiMH/NiCd batteries. The design supports fast charging of batteries with different configuration and capacity. The charger periodically monitors the battery parameters; voltage, current and temperature; calculates the voltage and temperature gradient; for precise measurement and control of battery charging. The proposed design provides multiple charging current options with automated selection of optimum charging rate for the battery being charged. The novelty of this design lies in accurate procedure adopted to end the fast charging cycle; this ensures complete, fast and safe charging of the battery pack. The design is implemented using an 8-bit microcontroller which controls and monitors the charging operation. The battery status and parameters are displayed on an LCD. Reentrant procedures are adopted in software writing that enable common software to control multiple batteries simultaneously. The proposed design is implemented and tested on NiMH and NiCd battery packs, which confirm the utility of the proposed design.