A novel method to ensure full recharge of a VRLA battery string

24-cells in series is most often used in telecommunication applications to build a storage battery string. The individual cells are very seldom identical or they may even exhibit high inequalities in the beginning of usage. This may result in difficulties to ensure full charge. Many charge-control methods have been proposed based e.g. on battery voltage, recharge time, behavior of final charge current. Neither of these methods will ensure full charge in a reasonable time. This paper describes a method based on the behavior of the block-voltage match error that can be effectively used as an evidence of full charge. It can be used both in normal recharge and also in equalizing charge to ensure the recovery of full charge return. The uncertainty of full charge of every battery cells in series may also partly explain the unexpected short operational life of a VRLA battery