The switch between STOR and BAT initially closes for 50ms to charge the 4.7uF capacitor on STOR (CSTOR). If the battery does not charge the capacitor above the user set VBAT_UV threshold, the switch opens but its body diode still allows current to flow from STOR to BAT. A load on STOR or BAT could significantly slow or even prevent CSTOR from charging above the 1.8V cold start threshold or the UV threshold. Therefore, we recommend isolating the load from STOR or BAT with a switch that is controlled by VBAT_OK.
The IC was designed with the expectation of a battery being connected only after the previous battery has been depleted or is damaged. The switch between STOR and BAT will only close if the voltage on BAT and VSTOR is less than a few hundred millivolts just before the new battery is installed. Therefore, before hot plugging a good battery, you should remove the old battery, power down the IC and discharge CSTOR and the battery capacitor (CBAT).