Can a wireless power transmitter charge a 3.7V battery?

In this tutorial, we will build a wireless power transmitter and receiver that can transmit enough power to charge a 3.7V battery. In a wireless power transmitter, incoming power is converted to a high frequency oscillating signal. This oscillating current is then sent to a wire coil.

Why do batteries need to be connected in a circuit?

With this analogy, it is plainly obvious why both the positive and negative ends of a battery must be connected in a circuit. If, say, you connect only the negative electrode to ground, there is no current because there is no electricity coming in on the positive electrode that can be pumped out.

Can a current flow in a battery?

Maybe something like "Current flow in batteries?" Actually a current will flow if you connect a conductor to any voltage, through simple electrostatics.

What happens if you put a wire between a battery?

When you add a wire between the ends of the batteries, electrons can pass through the wire, driven by the voltage. This reduces the electrostatic force, so ions can pass through the electrolyte. As the battery is discharged, ions move from one electrode to the other, and the chemical reaction proceeds until one of the electrodes is used up.

How does a wireless power transmitter work?

The power receiver has another wire coil, which picks up the magnetic field from the transmitter when placed near it. Since a varying magnetic field generates an electrical current in a wire loop, the transmitted magnetic field is converted to an electric current in the receiving coil. Here is the schematic for a simple wireless power transmitter:

How does a battery work?

The confusion here is from the initial poor description of how a battery works. A battery consists of three things: a positive electrode, a negative electrode, and an electrolyte in between. The electrodes are made of materials that strongly want to react with each other; they are kept apart by the electrolyte.