How would I retrieve the Power Expander battery to a variable?

How would I retrieve the Power Expander’s battery to a variable? In EasyC, under “Battery”, we can only get main and backup battery values. Does anyone know a solution to this situation? Thanks.

Running EasyC v4 for Cortex, version 4.2.1.7, Cortex firmware version 4.22.

The formula is in the wiki for the power expander.