You know I have never understood this sparking problem that some people have. Why would a controller spark when it's pluged in? Sparks are caused because a load is being drawn when the wires are connected. If you plug in a toster it doesn't spark. But if you have it activate (making toste) and you plug it in it will likely spark. The controller should act the same way. There is little to no load on the controller when you plug it in so it should never spark. I have 4 ebikes and none of them have ever sparked when pluged in or turned on. Just my opinion but I think it you are getting sparks when you plug in the controller there is something wrong.