RTC Battery Life

I have a Jetson Nano configured with a diode and ML1220 rechargeable battery. However, I have noticed on a couple separate occasions that the RTC will fall out of sync if the device is not powered on for 2-3 weeks. Is this normal?

I understand the battery is supposed to provide 2.5-3.5V, and other posts say it can run with as little as 1.65V. I can start measuring the voltage of the battery cell over time, but that means I’ll have to not power on the unit for a few weeks.

The RTC power consumption is about 2uA, the voltage can be low to 1.65V. You can calculate the working time based on that and the capacity of your battery.