This fixed two different bikes at Prostar Chicago. It is always best to test it in the pits before you go up to make your run. This is true even if you have the large amp NX solenoids. When charging your battery on your motorcycle equipped with a Schnitz Box, or even a Dyna 4000 unit, make sure your ignition switch is off. Some battery chargers will put out an initial voltage spike of 50 volts when first connected, that why you see all the sparks fly .
Some battery chargers use the battery itself to help control the voltage spikes.
Good rule of thumb - Never use more than a 2 amp charger on any bike battery. We had two ignition boxes at Chicago that were zapped this way.