The jump stater is designed to "start the car" as the main output,  multiple cells are discharged in series at the same time to output a stable current when the car is started; in charging the phone, is also a few batteries at the same time to discharge 12V electricity, and then forcibly converted to USB 5V current output, so charging cell phones and other USB devices, power consumption than ordinary Charging battery is faster than normal; this is the normal situation, please rest assured that use.