The paper describes the results of a diagnostics research of automotive starting batteries. For the purpose of the experiment, seven lead-acid batteries of different capacities, starting currents, structures, lengths of operation and levels of exploitation were used. The tests were performed in similar conditions and the preparations included charging up and cleaning the batteries. The experiments were realized on measurement site and in a motor vehicle with the use of battery chargers, electronic testers, diagnoscope, analog and digital measurement apparatus. The tests on measurement site included checking the technical condition with testers and evaluation the voltage-current characteristics. The tests in the vehicle were performed when starting a combustion engine, when it was idling as well as with the engine turned off but with working electrical receivers. The electrical values for specific batteries and receivers were measured, recorded and calculated by means of a diagnoscope and other instruments. On the basis of the results, a comparative analysis was conducted with special attention paid to the most differing results. The set physical values were compared as well as the recorded changes of voltage and current. Finally, an attempt was made to assess the condition of batteries and their usefulness in a motor vehicle.