Apple has acknowledged the problem of overcharging and has on that occasion implemented a feature called "Optimized charging". This means that the phone will slow down the charge from 80%, to reduce the time the battery is connected to the charger after 100%. This function can in some cases cause the cable to stop charging at 80%.
By using apias' smart cable, you can turn off the "Optimalized charging" function. You will then achieve full battery charge, without the wear and tear by being connected to the charger longer than necessary.