[Alan Anderson]

The NI 9201 analog input module is only supposed to be capable of reading a maximum of ten volts. The Analog Breakout has a 680ohm/1k voltage divider in the circuit to reduce the battery voltage to something within range. The calculation of the number to display compensates for this. If somehow you're getting full battery voltage on the NI 9201 input, and if it is somehow returning that value (which is greater than it is specified to handle), you'd see about 17.68 volts on the display. An open circuit in the 1k resistor path would do it.

Your team probably has a spare Analog Breakout (one came in the kit this year and last year, and there were two with the first year's cRIO). Try swapping out the one you're using now and see if the voltage display becomes correct.