These sensors do a good job and are relatively inexpensive. But their housing is made of a conductive resin plastic and is shorted to ground by the internal PCB mounting screw. For FRC use, this means you'll see on the order of 100-200 ohms between battery V- and a metal chassis unless the mounting isolates them properly. Refer to the competition checklist for the minimum allowed resistance between battery V+, V- and chassis.