VDD_RTC and Super Cap "battery" life

I am trying to calculate how much time a fully charged supercap connected to the TX1 module will
last once power is removed from the module.

The supercap part used on the TX1 motherboard is Seiko P/N: XH414HG-IV01E.
It is rated as 80MF, 3.3V.

What voltage does the TX1 charge this cap up to when main power is present?
What is the current draw of the TX1 module from VDD_RTC when main system power has been removed?

Supercap is charged to 2.45V~3.00V, the typical current is 2.0uA~2.2uA

I am trying to use this calculator to compute the battery life:
https://www.maximintegrated.com/en/design/tools/calculators/product-design/supercap.cfm

I need to know the threshold voltage below which the RTC will no longer operate in order to compute
how much time the supercap can power it. Is there any information about it?

Thanks!

RTC can operate down to 1.65V