I have void pro rgb wirelles headphones. They are new, but they don't charge to 100 percent. They are still connected, and after disconnecting from USB there is max. 96% battery. If they are connected longer, the battery charge percentage drops to 92, and it oscillates anyway. Is this normal on this model? The green diode does not light up and I do not know when they are fully charged. Corsair, please help.