This thing goes INLINE with the disconnected pos or neg main power lead to the battery. Size the shunt so it does not overload. Google PRECISION LAB SHUNT. Keep in mind meters that are loop powered (2-wires) rob X milliamps from the process. Making readings less accurate a LCD voltmeter a 4-1/2 digit powered with say a nine volt battery will be astoundingly accurate and if a lithium battery is used with a switch, it will become a "for life" calibration tool. Be sure to DeOxit the power plug and socket on the meter occasionally. This is a hyper-sensitive connection
