Here is what I have observed
Limiting input to 13 amps @ 122 volts (1586 watts) limited output to 108 amps @ 14.6 volts DC
If the output is linear then 15 amps @ 122 volts (1830 watts) ought to limit output to 125 amps @ 14.6 volts DC.
If we drop the input volts to 120 @ 13 amps (1560 watts) should limit output to 106 amps @ 14.6 volts.
So 120 @ 15 amps (1800 watts) should limit output to 123 amps @ 14.6 volts
At 115 @ 13 amps (1495 watts) should limit output to 102 amps @ 14.6 volts
So 115 @ 15 amps (1725 watts) should limit output to 118 amps @ 14.6 volts.
So BFL13 is correct a 15 amp shore power is probably not going to do 125 amps--unless the voltage is on the high side.