BFL it amounts to basic ohms law. I "oversophisticated" my interpretation of your primary example.
Here is a DIRECT comparison between an excellent condition group 31 Johnson Out Of Control group 31 and a Lifeline 31. Done by me.
Starting voltage of the JC somewhere around 12.15 Connected to the Borg. Instant 14.4 volts 47.7 amperes. Lifeline higher starting voltage 12.2 something (does it matter?) Voltage same setting. Instantaneous 107 amperes @ 14.0 something did not reach Vmax for several minutes. These were casual notations not a trial.
The increased charge receptivity was absurdly distorted. Time versus amperage. Similar 20 hr rates between accumators. If the difference was less than gargantuan then I would take an interest in this. But trying to discover if the world is square and not flat raises some other types of issues. Or as they say: An oval shaped wheel was not a contender...