OK let's forget the whole CCA (Cold Cranking Amps) thing since a battery CCA rating has nothing to do with it. CCA is a rating used in the battery industry to define a battery's ability to start an engine in cold temperatures. The rating refers to the number of amps a 12-volt battery can deliver at 0°F for 30 seconds while maintaining a voltage of at least 7.2 volts. That aside, when I start a car or truck and engage the starter motor the starter motor is a high current DC motor. The common method to actually measure the starter motor current is using a simple clamp on current meter. Clamp On current meters can measure AC current, DC current even true RMS AC current. So I place my clamp on meter on that large heavy cable running from Battery + (Positive) terminal (Negative if you prefer) to the starter and crank the engine. At no point is my current meter actually touching anything, it's just there. So how does it read current? How does a Hall Effect sensor read current? They are not wired in series with the load so how do they work? Now want to take bets on a magnetic field around a current carrying conductor? Got an old magnetic compass? Lay it beside a current carrying conductor let me know how that works out for you.so that leaves me with more doubts, like a million of them, like then what if 450 CCA are on ground and the starter motor positive cable? that wont generate a electro magnetic field like the one you mencioned and probably burn things up? not trying to discuss with you, just want to order the things on my mind
A million doubts is fine like a million questions. You start with number One and work from there.