Method of self-discharge test for secondary battery and manufacturing method for secondary battery

A method of self-discharge test for a secondary battery comprising an electrode body provided with a positive electrode plate including a positive active material layer and a negative electrode plate including a negative active material layer,

• the negative active material layer including an opposing portion opposing the positive active material layer and a non-opposing portion failing to oppose the positive active material layer, wherein
• the method includes:
• adjusting a battery voltage to a first battery voltage by any one of charging and discharging of the secondary battery;
• and
• self-discharge testing a state of self-discharge of the secondary battery by variation in the battery voltage for a predetermined term for which the secondary battery is kept in a terminal open state, and
• the adjusting the battery voltage is to adjust the first battery voltage having magnitude which satisfies a variation settled time of 17 hours or less from adjustment completion time of adjusting the battery voltage to the first battery voltage, the variation settled time being a time of settling a variation amount of the battery voltage varied by diffusion of charge carrier atoms that are diffused to lessen a concentration gap between an opposing-portion concentration as a concentration of the charge carrier atoms existing in the opposing portion of the negative active material layer and a non-opposing-portion concentration as a concentration of the charge carrier atoms existing in the non-opposing portion of the negative active material layer.