I have the RTC Pi V1 module, which I bought in 2013. This is the old version with 26 pins (see attached picture). Currently I use it with a ROCK64 board, which is pin compatible with Raspberry Pi. I can set/get the date and time via i2c bus. When I restart, or power off the board, it works without any problems. But when I unplug the power cord and plug again, the RTC module is reset to year 2000. I changed the battery but that did not help. What may be the reason? Thanks in advance.