You need to extend voltmeter clips with meter in car (have a passenger watch it now

) it can ALMOST be like reading a data stream IF someone is recording video AND capturing comments , thoughts , observations . For with a battery IN car ................VOLTAGE is the key sounds like in your case ???
p.s. Still sketchy ?? A-zone and O'relly has load boxes and professional battery test eqipment , you can squeeze them in at the points of your choosing , cause AMPS may NOT reflect as great as the so-called " good battery voltages " you may be seeing ?
