Coulometer

Abstract: Abnormal battery depletion can be detected in an implantable medical device. Battery capacity consumed can be measured using a coulometer and using a capacity-by-voltage device, and the measurements can be blended to determine battery status. A drop in battery voltage below a specified threshold can be detected to identify a high-current depletion fault, and an alarm can be provided to indicate the fault has been detected. The specified threshold can be determined as a function of battery capacity consumed. Other aspects and embodiments are provided herein.

Abstract: A thin film coulometer for use as a battery state of charge indicator in which the indicator is located on a battery and connected in parallel across a current path of a resistive segment of the battery so that during discharge, the coulometer can be observed to indicate the capacity of the battery. The coulometric charge indicator device may have a variable thickness construction and include indicia which are produced upon battery discharge.

Abstract: A computer for determining the time remaining at the present rate of energy dissipation before a finite energy source is completely drained of energy. The rate of energy consumption is sensed and then modified by a function generator in accordance with the effect that the rate of energy consumption has on the quantity of energy available from the source. The modified rate of dissipation, i.e., effective rate of energy dissipation, is fed to a coulometer having an output capacitance which is varied in accordance with the integral of the modified signal. The change in the output capacitance is measured by feeding a high frequency interrogation signal to the coulometer. This signal is developed across the output capacitance thereof and accordingly has an envelope which is proportional to the integral of the modified rate of energy dissipation. The developed signal is amplified by an AC amplifier and demodulated by an envelope detector. The demodulated signal is then subtracted from a predetermined value representative of the total rated energy in the system. This resulting value represents the energy remaining in the system. This energy remaining value is then divided by the modified rate of energy dissipation to provide the time remaining at the present rate of energy dissipation.