Title: +038=360.000-OU045T_03-PCD2.m4160 PLS SBC - Hardware Manual.pdf
31) Depending on the ambient temperature; the higher the temperature, the shorter the buffer timeWith new controllers, the batteries are packaged with the units, and have to be in-serted on commissioning. Observe the polarity of the batteries:Insert Renata CR 2032 coin cells in such a way that the Plus pole points in the direction of the embossed plus sign on the housingBattery changing Remove PCD cover Pull locking clip in the direction of the embossed plus sign on the housing (see arrow) Remove old battery Insert new Renata CR2032 battery in such a way that the  Plus pole is in contact with the locking clipCPUs with lithium batteries are not maintenance-free. The battery voltage is monitored by the CPU. The BATT LED lights up and XOB 2 is called (if XOB 2 is not programmed, the ERROR LED will also light up after 1 second of battery failure), where  the battery voltage is less than 2.4 V the battery is flat or shows an interrupt the battery is missing