Are you using the EDU header files? For those two fields (rc_*_batt), I have "res01" and "res02".
In ifi_aliases.h (EDU version), it has this macro:
Code:
/*
*-------------------------------------------------------------------------------
*---------- Alias for Battery Voltage -----------------------------------------
*-------------------------------------------------------------------------------
* current voltage = battery_voltage * 0.038 + 0.05;
*/
#define battery_voltage rxdata.rc_analog01
Also, I'm pretty sure the formula is known to be inaccurate.