A method for determining the amount of charge which can be drawn from a storage battery includes determining a battery voltage and current profile over at least one time interval; smoothing the battery voltage profile and the battery current profile using at least two different smoothing measures; and determining voltage and current differences between battery current and voltage profiles smoothed using a second and third smoothing measure, with the third smoothing measure producing greater smoothing than the second smoothing measure. The method further includes calculating characteristic values from quotients of the voltage differences and the current differences; utilizing the characteristic values for a time interval to determine an interval characteristic value; and determining the amount of charge which can be drawn from the storage battery from at least one interval characteristic value for at least one time interval. A monitoring device may be provided for carrying out the method.