7.4.2 Test procedure7.4.2.1 High-po

7.4.2 Test procedure7.4.2.1 High-power battery system The no-load SOC loss shall be measured with a complete and fully operational battery system. The BCU shall be supplied with the necessary auxiliary power (e.g. 12 V d.c. power supply) in order to be able to control necessary battery system functions during the rest period, for example: a) battery system cell balancing, and b) periodical BCU wake-up activities. The no-load SOC loss rate(s) shall include any possible parasitic or operational discharge contribution of the cell balancing circuitry itself beyond the inherent self-discharge rate of the battery cells themselves. The no-load SOC loss rate of the battery system shall be measured for three different rest periods and at two different temperatures. The battery system is discharged to 80 % SOC (or to an SOC agreed between the supplier and customer) and then left at open circuit for a certain time. The BCU shall be able to perform control activities (e.g. cell balancing and regular wake-up activities). After the rest period, the remaining SOC shall be determined by a 1 C discharge at RT. The tests shall be performed in a temperature-controlled test chamber at the given temperatures according to the test sequence in Table 13 and Table 14. Before each test cycle at a given temperature, the battery shall be kept at the test temperature for a minimum of 12 h. This period can be reduced if thermal equilibration is reached, specified as less than 4 K change among individual cell temperatures during an interval of 1 h. Temperatures: RT and 40 °C. Standard cycle: to ensure that each test is done with the battery system in the same initial condition, an SC (see 6.2) shall be performed prior to each test;Discharge rate: discharge the battery system to 80 % SOC (or to an SOC agreed between the supplier and customer) at 1 C rate;Rest period: 24 h (1 d), 168 h (7 d) and 720 h (30 d);Auxiliary energy: auxiliary energy consumption (e.g. 12 V d.c. level) for the BCU and, if required, for other battery system electronics shall be