I have checked by external debugger and it seems that
batteryservice:update start runs 10 times per second. Other battery processes are running very often too, only with charger unplugged. It's brand new Samsung GT-S7562. What can cause this? Is there any chance to repair it on warranty rules or should I send back to seller?
edit: I have locked cpu frequency to max and noticed no changes in cpu usage. Also checked for frequency decreasing when charger unpluged and see no association with this action.