After over 24 hours since I synced both my computer and the RTC after our hour change here in the US, I tested it this morning to see how much it drifted.
I had the module unplugged so the time was being kept by the battery.
Only 1 second compared to the PC that fell behind 5 seconds in about 26 hours (I thought it was 27 but we lost one).
Oh, of course I modified the time format to our odd way to tell time