Remote battery plant monitoring system

A system for monitoring performance of one or more batteries in a battery plant facility. A set of sensors for each battery are used to measure a plurality of battery operation parameters comprising the battery current, battery voltage, and internal battery temperature of each said battery. A processor generates, for each battery, a plurality of battery status parameters comprising a true age parameter and a float capacity parameter. During a float period, the true age parameter is updated based on elapsed time corrected for battery temperature history and the float capacity is updated based on the most recent true age parameter. During a discharge period, the float capacity parameter is updated based on the evolution of plant voltage during the discharge. After the discharge period, at the beginning of a subsequent float period, the true age parameter is updated based on the float capacity parameter determined during the immediately previous discharge period.