14.14.4.1 Prepare measurement a) O

14.14.4.1 Prepare measurement a) Operate the system at the rated electric power output for more than 30 min before starting the test. b) For systems including batteries, operate the system at rated electric power output for more than 30 min and until a known nominal state of charge of the battery is reached, before starting the test. c) Systems may be equipped with a means (for example, a display method or an output signal) to identify that the battery has reached a known nominal state of charge (including full charge state) that is determined by the manufacturer. NOTE In the absence of such an indication, the results of energy consumption and efficiency calculations will be less precise. See 14.5.1. d) Set the temperature of the returning fluid at a level appropriate for the recovered heat usage conditions. Control the amount of cooling fluid entering the thermal load to maintain the said conditions throughout the test. 14.14.4.2 Electric efficiency Fuel cell power system starts to operate using electric load device which simulates electric demand pattern. Total electricity generated and total fuel input shall be measured.