An uninterruptible power source, with a laboratory testing option, for battery-powered systems
This paper describes a monitoring circuit for battery-powered, printed circuit board systems. The circuit, which can be used with various battery technologies, is designed to act either as an uninterruptible power source for field use or as a battery testing module for laboratory use. It operates with one battery as the main power source and another as a reserve, using the stronger of the two batteries to provide system power based on a preset voltage differential. Field-effect transistors (FETs) with very low on-resistance minimize dropout voltage, and special drivers ensure that the transistors operate in full saturation. The circuit can be utilized in engineering and technology laboratories to demonstrate battery discharge curves, measure individual battery performance, and measure battery energy density, all of which are useful in comparing and contrasting the performance of different battery technologies.