Thevenin Equivalence Problem
Theravin equivilent would be 

12.2V - 11.88V (the voltage across the resistance) = 0.32V,

0.32V / 7A (the change in current that made that voltage) = 45.7 milliohms

Now we have the resistance, just need to reverse out the source voltage

1A * 0.0457 = 0.0457V, 

So 12.257V with a resistance of 45.7 milliohm,