(EP447928-B1)      Method of determining the state of a lead-acid battery, in particular a starter battery, in which the battery is discharged with a discharge current for the duration of a limited time interval and in which the cut-off voltage at the end of this time interval is measured for determining the state of charge of the battery, comprising the following method steps: (a) in a first discharge step (phase 1), the battery is discharged for the duration of a few seconds to compensate for the so-called transient voltage drop with a high first discharge current; (b) in a second discharge step (phase 2), the battery (38) is subsequently discharged for the duration of a few minutes with a predetermined, relatively low, constant second discharge current (I20); (c) at the end of the second discharge step, the battery temperature and the battery voltage are measured with the aid of temperature-measuring and voltage-measuring devices (12 and 14, respectively); (d) in dependence on the measured battery temperature and the measured battery voltage, the relative state of charge of the battery to be tested, with respect to a fully charged battery of this type, is established from data of a first family of state-of-charge curves stored in memory devices; (e) in a third discharge step (phase 3), the battery is discharged for the duration of a time interval of a few seconds with a precisely predetermined high, constant third discharge current; (f) the cut-off voltage achieved in the third discharge step is measured with the aid of the voltage-measuring devices (12); (g) with the aid of comparison devices (10), the voltage difference is established between the value of the measured cut-off voltage and a voltage value which, according to the data of a second family of state-of-charge curves filed in the memory devices, would apply for an as-new battery (38), taking as a basis the state of charge established at the end of the second discharge step (phase 2), at the temperature established at the end of the second discharge step (phase 2) and at a discharge with the precisely predetermined high, constant third discharge current; and (h) on the basis of the established voltage difference, the relative loss of starting capability corresponding to the state of charge, with respect to an as-new battery (38) of the same state of charge, is established from the data of a curve assigned to the loss of starting capability of the battery type to be tested stored in the memory devices (10), or the relative starting capability still existing at the time of the test is established, the first and the second family of state-of-charge curves comprising predetermined curves which apply for the battery type to be tested and for the second and third discharge current, respectively, and link the battery voltage and the state of charge to each other at the temperatures concerned.