Hi,
First, congratulations on your modification. With your power solution, the watch runs much quieter than mine. Secondly, it's nice that someone after five years is still digging up this (underdeveloped) project and trying to do something about it

.
The mysterious 00:00:80 is a familiar mystery in the case of the DS1307. This strange eight is the highest bit in the seconds register. To quote the datasheet
Quote: Bit 7 of Register 0 is the clock halt (CH) bit. When this bit is set to 1, the oscillator is disabled. When cleared to 0, the oscillator is enabled. On first application of power to the device the time and date registers are typically reset to 01/01/00 01 00:00:00 (MM / DD / YY DOW HH: MM: SS). The CH bit in the seconds register will be set to a 1.
This means that it was not so much the DS did not take off as did not start

. This is because this project uses a very twisted time setting system, which requires you to upload two different hexes one after another

. One of them has a compiled time which it sets and thus deletes that control bit, and the other one does not do it anymore. To check if the watch will start, I put a hex in the attachment, which should set the time to 15:00 with today's date. If you upload it at 3 p.m. with the backup battery inserted, and then, without turning off the power, you upload the hexa available in the archive on the first page of this topic, the time will be read correctly forever.
However, there is also a modification that I do not know if I mentioned on the previous pages of the topic. Namely, it is a resistor pulling the break line from DS. Without it (or without any changes in the software), the time, although it will be different from 00:00:80, will not change. I marked the resistor in question in the photo.