【課題】 極板の化成工程中に電解液量が不足すること なく、電池活物質を極板全体に均一に化成する。
【解決手段】 充放電工程後の充電工程の間で、セル当 たりの電圧が、２.５Ｖから２.８Ｖの範囲に達したとき に、電解液の第２回目の注液工程を行う。
PROBLEM TO BE SOLVED: To uniformly form a battery active material in the whole electrode plate, reduce the dispersion of electric capacity between cells, and prevent decrease in the battery life by replenishing an electrolyte when voltage per cell reached the specified range in the formation process of an electrode plate. SOLUTION: A first electrolyte poring process for pouring the specified electrolyte into a battery container from a pouring nozzle is conducted. The specified charge/discharge processes are successively conducted while voltage across the terminals is measured. When the voltage per cell reached the range from 2.5V to 2.8V during the charge process after the discharge process, a second electrolyte pouring process is conducted, then the remaining charge process is conducted. The formation of a battery active material is uniformly performed over the whole electrode plate without shortage of the electrolyte amount during the formation process of the electrode plate.