Abstract: Method and apparatus for measuring the voltage and state of charge of a secondary battery. The voltage and state of charge values are taken by a circuit every four (4) seconds by reading voltage, waiting two (2) seconds, reading current, waiting two (2) seconds, and repeating the voltage readings and the current readings. The circuit includes a 4-bit microprocessor, CMOS analog switches, and two operational amplifiers. The voltage and current readings are taken from dual-sloped converters, and the values determined by software algorithms in the microprocessor.

Abstract: A battery maintenance system for charging, analyzing, discharging and conditioning of a NiCad battery. The system displays voltage and capacity to determine whether or not a NiCad battery has enough capacity to power equipment for an optimal time period. The system charges the battery using a negative delta voltage method of detecting full charge, while also displaying instantaneous battery voltage. The system also analyzes the battery in a charge, discharge and recharge mode of operation, and during the charge mode the instantaneous voltage is displayed. The discharge mode discharges the battery to one volt per cell while displaying voltage and accumulative capacity alternately. The system also conditions batteries by cycling a battery through three cycles of charging, discharging and a subsequent recharge cycle.

Abstract: Method and apparatus for measuring the voltage and state of charge of a secondary battery. The voltage and state of charge values are taken by a circuit every four (4) seconds by reading voltage, waiting two (2) seconds, reading current, waiting two (2) seconds, and repeating the voltage readings and the current readings. The circuit includes a 4-bit microprocessor, CMOS analog switches, and two operational amplifiers. The voltage and current readings are taken from dual-sloped converters, and the values determined by software algorithms in the microprocessor.

Abstract: The characteristic voltage-versus-time curve for a nickel-cadmium battery on a fast charge, e.g., being charged at the C/1 rate, increases to a peak voltage and thereafter decreases. To ensure that the battery is fully charged, the fast charge is discontinued on the decreasing portion of the voltage-versus-time curve. The fast charge may be stopped when a predetermined negative rate of change of the voltage is obtained. Or the fast charge may be cut off when the battery voltage decreases a predetermined amount below the peak, that is, when the difference between the maximum measured battery voltage and the present battery voltage exceeds a setpoint. After the fast charge is discontinued, a trickle charge, e.g., a C/10 charge or less, may be instituted or the charging current may be interrupted altogether, i.e., the battery charging circuit may be opened.