I will try to word this the best I can here...
When you hook up the stinger volt meter to the amp,do you use a different length of wires to read that voltage than what you would use to read the battery. Like you use a 5 foot wire to read battery and then a 12 foot wire to read amp? Because if you use a different lengthed wire then you will have to calibrate indivisually each time otherwise the voltmeter will not be accurate.