I’ve been getting a little fed up with having to reset the date when using the standby switch since the RTC is powered by the main battery. I started looking at the schematics and it looks like if I remove R19 I could wire a CR2032 holder between VBatt (pin3) and VSS/GND (pin4). Any thoughts?
OK, its been slow at work and I scrounged up some CR2032 holders. Gave the mod a try and it does indeed work as expected! With standby switch opened for 10 minutes the date remained unchanged when closing and powering back on.
The chip is very small and was difficult to work with for me with the naked eye, but I did the best I could. It also annoyingly is lacking a divot to help orient it. Identified GND pin by looking for which pin was connected to the largest patch of copper instead of just a trace. Verified with meter.
RTC Chip (U11) is under the SOM. I removed R19 by putting a glob of solder on my iron and dipping it over the resistor and that picked it up. I ended up redoing the positive (red wire) and putting a piece of Kapton tape over the crystal, to ensure it wouldn’t short. I took the picture before going back and doing that though. then I taped everything down with Kapton before reseating the SOM.
Used a bit of double-sided tape to keep battery out of the way and secure.
Will probably have it off for a few days this weekend to check how it holds up with a longer period of time with standby switch opened.
Edit: Worked over night with standby switch off for 13 hours.
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