Chances are that your charger wires are capable of carrying circa 5 amps or so and are sized to carry out that task over many hours. The size of the cables on a jump pack kinda give the clue that something different is likely to happen when it is connected into a circuit.. ?
For sure the jump pack does not have many hours of capacity stored within, it is designed to provide max power over a short period of time.... As for the amount of current... there are many factors at play, A starter motor is the equivalent of an electrical short for a fraction of a second until it starts to rotate, as for the initial current surge...? I could only guess but lets suggest 500 amps to give a very rough idea, as for the effect on your charger sized wiring rated at 5 amps..?
Time is also very much part of the calculations when it comes to picking cable sizes and just how stressed your charger sized wiring might become, seems likely to correspond to the length of time you expose it to the loading of trying to fire up the engine connected to a starter pack....
