So I have a car A with dead battery but good everything else and a car B with good battery.
What I did was disconnect car A's dead battery, connect car A's terminals directly to car B's battery. When I connect the two batteries together (+ to +, - to -), I cannot immediately start the engine of the dead car, even if the good car's alternator is running. Why is that? Shouldn't the power from car B's battery be enough to start car A?
The power from car B should be diverted to car A to start its engine.