illuminated ball - remote switching and charging
I'm working on making an illuminated ball for playing bike polo with at night time. A couple of high output red LEDs are sufficient for light to get through a normal street-hockey ball. The problems I'm currently facing are switching the lights on or off, and charging the batteries. Ideally both of these could be done remotely - i.e. without having to open the ball up.
For switching I was thinking of using a magnetic reed switch - when a magnet is attached, the lights switch off. The only problem is that reed switches seem to be (a) made of glass (not ideal when the ball gets hit really hard), and (b) in a normally-open configuration - I'd need a normally closed one for this.
As for charging, I have two ideas - one is to have two small metal pads on the surface of the ball to connect to the charger. This could be problematic due to forces on the ball during gameplay. The other more fun idea would be inductive charging. Like what you get in those fancy electric toothbrushes. One coil inside the ball, one outside. How practical is this? can it supply the necessary voltage and current to charge either a pair of NiMH batteries or a Li-ion cell?