Matters needing attention: 1. Turn on flashlight to discharge, then charge for over 4 hours before starting car. 2. Do not discharge and charge at the same time. 3. Charge every 3 months, low power may fail start. 4. Charge phone tablet only occasionally, efficiency is about 50%. 5. Charge speed or discharge speed will be fast during the last 15% power of the jump starter. Please do not worry about these problems, it's the characteristic of high-rate lithium batteries and will not affect product quality and normal use. Why it's necessary to get a jump starter? 1. Long standby time run out battery. 2. Make preparation for a long driving trip. 3. Your car can't start due to low power or freezing winter.