Abstract: A battery performance monitoring system anticipates the sudden fall of battery output. The system measures the battery voltage at a time point when the discharge current of a battery becomes smaller than the reference current value or at a time point when the current to the load which is connected to the battery becomes smaller than the reference current value, and judges the battery to be abnormal if the difference of the measured battery voltage from the approximate formula in regard to the current-voltage relation in the former half of a same discharge event becomes out of the reference range.

Abstract: The aim of the invention is to provide a battery controller which is able to secure the number of rewrite time as required without replacement. The battery controller including a plurality of memory groups 104a to 104n comprising nonvolatile memories rewritable on the basis of one unit or plural units, a switch for selecting a memory group and a reader/writer 102 for writing or reading data into or from the memory groups, wherein the switch selects sequentially a memory group, according to a signal for writing from outside.

Abstract: A battery performance monitoring system anticipates the sudden fall of battery output. The system measures the battery voltage at a time point when the discharge current of a battery becomes smaller than the reference current value or at a time point when the current to the load which is connected to the battery becomes smaller than the reference current value, and judges the battery to be abnormal if the difference of the measured battery voltage from the approximate formula in regard to the current-voltage relation in the former half of a same discharge event becomes out of the reference range.