Why Do Cables Affect Charging Speeds? I had P1 Turbo with 5000mah battery. It's SC-13 could  0-100 in under a hour even with wifi enabled.

The charger is broken but I keep the cable. I use a third party 2.1A charger with dual ports. The weird thing is. My G7102 and Note 3 N9000 gets charged slowly with that cable compared to the original cable of Ace 2. Ampere says Samsung cable gives more than 2 times amperage.

Why is that? I don't know electronics can someone explain it to me why is that?
Because all cables have a resistance. This is affected by the length and cross sectional area supplying the power pins.

The formula is:


  R =  ρ L / A


(Where R is resistance, ρ is resistivity, L is length and A is cross sectional area).

Other factors are the plug itself and the amount of power it can draw. Also, factors like QC 3.0 compatibility allow the phone to pull more current at a higher voltage. Phones intelligently decide how much power to draw as well based upon their own tables, the temperature and charge and other properties of the battery.

But, in general, a cable with higher resistance or unable to pull as much power will charge more slowly. Just because a cable is rated for 2A doesn't mean it will achieve this.

To see more detail, I suggest you get a meter that will allow you to measure the precise current and voltage using the same USB plug and different cables.