The current consumption is determined if the battery IC is charging or not.
I found this information on this Datasheet: https://www.ti.com/lit/ds/symlink/bq24040.pdf?HQS=TI-null-null-digikeymode-df-pf-null-wwe&ts=1592255213282
If there is no charging happening:
Then you will look at the quiescent current on page 6:
Active supply current, IN terminal when conditions are TS = open, VIN = 6V, TTDM – no load on OUT terminal VOUT > VOUT(REG), IC enabled would be 0.8 to 1mA
While there is charging happening:
An external resistor will need to be used to Program the Output Current (50 to 1000mA) This can be used as a current monitor. Where conditions are RISET = KISET ÷ IOUT (1)
•IOUT is the desired fast charge current;
• KISET is a gain factor found in the electrical specification For greater accuracy at lower currents, part of the sense FET is disabled to give better resolution.
What this boils down to is BQ24040DSQR is watching the quiescent current while not charging to see if something needs to charge and when it is charging, it is using a resistor to make sure the current stays where it is supposed to be
Texas Instruments has a great article on Power Bank Charger Solutions if you need more or less current for charging: https://www.ti.com/lit/ml/slpt027/slpt027.pdf?ts=1592254875912&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ24040