Wireless Power

[From the last episode: We saw how we can change supply voltagesVoltage is what gets electrons to flow. It's analogous to water pressure, which gets water to flow. Voltage is measured in units of "volts.", whether with ACAlternating current (which is also alternating voltage). This is how power is delivered to homes and factories. or DCDirect current (which has constant voltage). This is what electronics require as an energy source..]

There’s another technology brewing for helping to charge battery-operated devices. It’s actually not new in concept, but it’s gaining some steam as multiple new players enter the market, each hoping to have a better solution than the other.

It’s called wireless powerTechnology that allows a battery to be charged from a small or large distance, over the air, without having to connect a charger., and the idea is that you can charge a battery without ever connecting a wire. It’s mostly focused on smartphones these days. Companies are trying to develop an ecosystemA group of related businesses that agree to work together, typically through a somewhat formal organization that may have a brand name. If something like that existed, for, say, produce sold in a grocery store, then the ecosystem might include select farmers, distributors, transportation companies, and grocery stores. in which you could go to a library or a coffee shop or the airport and charge your phone simply by setting it down. (Don’t forget to pick it back up!)

There are even ideas that would charge your phone – while it’s still in your pocket!

From Toothbrushes to Blenders

The first scenario operates something like the transformer we saw last week. The charger will be placed under a counter or a table or counter. The phone or other IoTThe Internet of Things. A broad term covering many different applications where "things"  are interconnected through the internet. device will also contain some circuitry that can talk to that charger wirelessly. If your device is close enough to the charger – it has to be able to feel the fields that the charger is setting up – then, just like the transformer couples powerThe rate of energy consumption. For electricity, it’s measured in watts (W). from one side to another, the charger can couple power from itself to your device.

You may be familiar with this from electric toothbrushes – this is the oldest version of the idea. In that case, you had a cradle, and you had to position the toothbrush (or whatever) very precisely to ensure that it charged.

Efforts today go into providing more flexibility on where you place your device. You used to have to position it within a millimeter or so (hence the cradle). Now it’s more forgiving, although, for this type of charging, you still have to be pretty close.

There’s even a version of this that aims to give you a spot on your kitchen counter where you can place appliances like a blender, and it will pick up its needed power from under the counter. The idea is to eliminate many of the power cords from the kitchen.

Using Radio Waves

There’s another version of this that’s not quite so far along, and it will charge things much more slowly. It uses radio-frequency (RF) waves to transmit power from the charger to your device. It can do this over longer distances – in theory, even without you taking your phone out of your pocket. You could walk into a store and have the ambient waves gently charging your device while you shop.

This is tougher technology to get to work, since, whenever you send out radio waves, you have to conform to regulations set up by the FCC in the US and corresponding organizations in other regions. This is necessary to make sure that devices are sending out frequencies that they’re allowed to use, that they’re not blasting out everyone else using that frequencyThe rate of change of a signal, specified in hertz, or cycles per second., and that they’re not bathing us with RF energy that’s too high and could potentially be harmful.

There Is a Catch

There’s one gotcha associated with wireless power. While developers are working hard to keep efficiency high, it’s still less efficient than using wired power. That means that more energy is wasted using wireless power.

In certain situations, where you don’t have a wired option, it can be really useful. But if you have both wired and wireless options, then, at least today, the wired version will use less energy.