How does this toothbrush recharge if it has no metal contacts between the base and brush?

Question

I have Crest® SpinBrush® - SpinBrush Pro Recharge toothbrush. My question is how does it recharge if there is no metal contact between the base and toothbrush?.Plastic is between the base and toothbursh.

Answer 1

Induction. There is a coil in the base that emits electromagnetic waves and a coil in the toothbrush that picks them up creating a low voltage inside the toothbrush which charges the batteries.

Answer 2

There are two coils (electromagnets), one in the brush handle, the other in the base. Electromagnets are only magnets when electricity runs through them.

However, if you just run electrical current through the coil, nothing happens in the handle's coil. What you need is electrical current that is constantly changing.
Now, as long as the electrical current in the base coil is constantly changing, it will induce a constantly changing current in the handle coil.

This is one of the beauties of AC (alternating current). DC (direct current), like from a battery, through a coil won't induce a current in another, but an AC current will induce another AC current in a second nearby coil. This is, in fact, how transformers work.

Of course, once AC is made in the handle coil, it needs to be converted to DC to recharge the handle's battery. This process inherently wastes a good portion of the energy used, and is why the handle gets pretty hot while charging.

For a more detailed explanation, look up "transformer" anywhere (not the toy, but the electrical component!)

Answer 3

Electromagnetic

[Edit]
To be more specific, something like a coil of wire in the base with an AC current stimulates another coil of wire in the toothbrush with an AC current. That stimulated current can then be used to charge a battery.

Answer 4

Either conductive plastic or through a transformer action.. base charger is the primary and tooth brush is the secondary.