after the input device and loading devices have been connected with the test specimen, and the power supply device shall reversely be connected with the specimen for 1 minute so as for the voltage thus applied to be kept respectively at 13V for the specimen of 12V system and 26V for it of 24V system, then after the power supply device has been disconnected therewith, the test specimen shall be tested for characteristics in accordance with 5.1 of this standard, where the results in respect of the specific performance shall be recorded.