Yes - This is very common. The sparking that you have when you connect the power connector into your E-Bike charging port. The controllers with large capacitors may have this issue, it's because you're filing the capacitors quickly and that's what cause the spark. Things You Can Do To Eliminate the Sparks - Some of our E-Bike models does have a Power on/off switch located on the Battery Pack. Switching the Battery Pack to the off position PRIOR to connecting the power connector into your E-Bike charging port could reduce the chances of seeing sparks.