Sunday, September 2, 2018

Would consumers subscribe to a service that keeps phones charged away from home?

Battery anxiety – fear of running out of mobile battery – is real, but how real is it and what are people willing to do about it?

The survey

In July this year, we surveyed over 1000 US adults to understand this. We asked them about battery anxiety, but we also presented a novel idea:
We are considering launching a service that would keep your phone charged pretty much all the time, without having to use a cable or a charging pad.
In a way, it would be like WiFi: just like you have access to WiFi at home, at work and in public places, your phone would be able to charge itself without your intervention at these places.
The phone would automatically charge anytime it is out of your pocket. For instance, you could place it on the kitchen counter, or on a table at a restaurant and it would charge.
And then asked the pricing question as follows:
If the service was priced at a monthly fee, how much – per month – would you be willing to pay for this service? Please enter a number in dollars per month.

Our findings

We summarized the results in an infographic – click here to see it in full. We also summarized them in a report and you can have the report free of charge by requesting it from Wi-Charge.
The results were very interesting. On average, people were willing to pay $14.48 per month for this service and some groups were willing to pay in excess of $25 per month.

What does this mean?

We believe that service providers should consider changing their mindset regarding long-range wireless charging from “a product accessory to be sold at our store” to “a service component that can increase ARPU”.
The mindset that wireless charging is an accessory probably stems from the experience of selling Qi pads. Qi pads offer added convenience relative to charging with a cable, but do not fundamentally change the user experience. The user still has to find the charger, carefully align the phone on it, and leave the phone on the charger.
In contrast, long-range wireless charging provides a dramatic improvement in the user experience:
  • Users must no longer actively manage the phone battery. Phones appear to charge themselves, without user intervention.
  • Users no longer need to carry cords or power banks with them.
Because of this dramatic improvement, users seem to be willing to pay a monthly fee for ‘charging as a service.
There is still a lot of work to make this a reality. A visionary service provider is required that is willing to make the necessary investments in marketing and infrastructure, but the potential is there for the taking.

Wednesday, August 29, 2018

Why RF wireless charging might be a good fit for electronic shelf labels

The other day, I read about a company making electronic shelf labels (sometimes also referred to as digital price tags) that is prototyping the use of RF-based charging to deliver energy to these labels.

This is a good news for the young long-range wireless power industry.

The problem being solved is real. A typical US store might have 50,000 such electronic labels. If they last 5 years on a battery, this means that on average 10,000 labels have their battery run out every year. If you were a maintenance crew that worked 250 days a year, you’d need to replace 40 such batteries or labels every day. That’s a lot of work.

I also think RF charging could be a good fit. Here’s why:

Electronic shelf labels require a tiny bit of energy, and thus are within the range that can be delivered using RF power.

Let’s make a technical back-of-the-envelope calculation: SES-Imagotag is a leading company in the digital price tag space. They publish specifications of their tags on the Web site. For instance, their G-Tag S4 label says that it uses a CR2450 coin Lithium battery and it is rated to last 5 years at 2 updates a day. These labels use epaper so they don’t require energy to sustain the display, just to update it.

A CR2450 battery is a 3V battery with a capacity of about 610 mAh, so total capacity of 1.83 Watt Hour (WH). Dividing this over 5 years and 365 days a year, it comes out that the required power is approx 0.001 WH per day, or 1 milliwatt hour per day. Thus, if you are able to deliver 1 mW for one hour each day, you can sustain this display ‘forever’.

In contrast, a low-end model of the Wi-Charge power transmitter can deliver approx 24 WH per day, so enough energy to serve about 20,000 labels, if there was a good way to get this energy to each label.

Electronic shelf labels are spread throughout the store, so a technology that ‘floods’ the space is helpful.

Putting safety considerations aside, if you think about RF energy like radio waves that flood the space, very small amounts of energy can reach around obstacles. Thus, they may be able to deliver these tiny amounts of energy even to labels that are hidden on a bottom shelf.

In contrast, IR wireless charging works best as a point-to-point mechanism. This is advantageous when it comes to power, range, efficiency and safety, but does present some challenges (which can be solved) when trying to deliver energy for a label that is hidden from view.

Monday, August 27, 2018

Which wireless power technology can charge a phone in your pocket?


Many people consider charging a phone to be the holy grail of wireless charging . Which wireless power technology can charge a phone in your pocket? Let’s find out.

Step 1: How much power does a phone need to charge?

The battery capacity of an iPhone X, typical of other smartphones, is about 10 WH. The operating time for an iPhone X under normal conditions is about 20 hours. This means that an iPhone X consumes about 0.5 Watt every hour.

Thus, if you wanted to keep an iPhone X operating ‘forever’, you’d need to deliver at least 0.5 Watt to it. If you can deliver 0.5 Watt, the energy that you are using is going to be equal to the energy you are providing. On average, anything above 0.5W can be used to charge the phone.

Step 2: Which wireless power technology can charge a phone OUTSIDE your pocket?

When energy passes through fabric, glass or any other material, some of it is scattered, reflected or absorbed. As a result, the amount of energy coming out of the other side is less than the amount of energy entering the material.

Thus, the task of charging a phone that is outside the pocket is easier than charging a phone inside the pocket, because more energy is available on the outside than it is on the inside.

Magnetic induction (Qi pads) can charge a phone on the outside if the phone is very close to the charging pads. Qi pads can deliver high energy – some claim up to 15 Watts – but require the phone to be in immediate proximity to the pad as well as nicely aligned. If magnetic induction delivers 10 Watts, it can fully charge an iPhone X in about 1 hour.

RF wireless charging cannot charge a phone. Under reasonable assumptions of transmitter size, and while keeping within international radiation safely limits, the theoretical limit for RF power delivery to a phone-sized receiver is about 0.1 Watt. That’s the theoretical limit, so practical implementation are usually much lower. 0.1 Watt is about 5x less than what you would need to keep an iPhone X operating. If the phone is turned off and is not consuming energy, and if RF delivers energy at the theoretical limit, it would take about 100 hours (over 4 days!) to fully charge a phone.

IR wireless charging can charge a phone. For instance, Wi-Charge today has units that can deliver about 3 Watts of power at a distance. See an example here. The theoretical limit is significantly higher. In fact, IR charging can safely deliver about 100x the energy of RF charging under reasonable assumptions. If a phone receives 3 Watts and consume 0.5 Watts, then 2.5 Watts is available for charging so a phone would be fully charged in about 4 hours. This is slower than cable or Qi charging, but wireless charging is more convenient: it can happen in the background without the need to put the phone away or connect to a cable.

Step 3: Which wireless power technology can charge a phone in your pocket?

We already established that RF charging cannot charge a phone outside the pocket, so it would also not be able to charge a phone inside the pocket.

Magnetic induction will not work either because it’s not practical to put the Qi pad right outside the pocket. If you were willing to do that, you might as well put a power bank in the pocket and charge the phone using a cable.

Wi-Charge also does not claim that a phone can be charged in the pocket using our current IR power technology. While we can demonstrate power delivery through several types of fabrics and other materials, we do not claim to be charging a phone in the pocket, nor currently work on that.

Thus, the answer to the question “Which wireless power technology can charge a phone in your pocket?” is (D) today, none of the above.

The silver lining

After a decade of charging cables and charging pads, the world in on the brink of long-range wireless charging and Wi-Charge is proudly leading this exciting transition. Before attempting wireless phone charging inside the pocket, I believe it is important to master wireless phone charging outside the pocket – an easier, but still very difficult goal that few were able to achieve.

I’m optimistic that remote non-LOS wireless power will arrive someday too, but don’t hold your breath. I’m currently unaware of any technology that can become the basis for non-LOS wireless power. In my estimation, it’s likely at least a decade away.

Friday, August 24, 2018

A framework for matching wireless power requirements to available technologies

There is a lot of interest in wireless charging as the next “cutting the power cord” revolution in consumer electronics. We often get asked
  • What the capabilities of today’s wireless charging are, and
  • How to best match the application with the right charging technology.
To answer these questions, we created a framework that explains the important attributes for a wireless power solution and discusses the performance limits of both infrared and RF technologies. The result is a simple graphical tool to help think about the best solution for a particular problem.

The framework can be downloaded here.

Saturday, August 11, 2018

What makes Smart Buildings smart, and how wireless power can help

Smart buildings are smart because they contain a lot of sensors. These sensors collect lots of data and this data is then analyzed to optimize comfort, power consumption and so forth.

Within reason, it’s good to have lots of sensors. With lots of sensors you can get very granular data about the building.

The sensors typically report their data through some wireless communication link: WiFi, 4G, Bluetooth, Zigbee, etc.

But how do the sensors get power? Today, they are either battery powered or wired. Battery powered sensors need to be consistently serviced so that the battery does not run out. If you have many sensors in the building, you’ll have a small army of battery changers. If the sensors are wired, the act of wiring them is expensive and time consuming. Now that the sensors are in place, re-wiring them with every move, add or change is also a pain.

This is where wireless power can help. If the sensors were able to receive power without wires, many benefits would emerge. No battery changes would be required. No expensive wiring jobs. If the building needed more frequent sensor reports, the sensor designer would not have to worry about a very limited battery power budget.

Changes would also be easy, and adding sensors to optimize the building would also not be as expensive as if they had to be wired.

In short, sensors make buildings smart. Wireless power makes sensors better and buildings smarter.

Tuesday, August 7, 2018

The biggest issue with today's phones is...


What is the biggest issue with today’s phones?

Is it that there are not enough pixels in the camera?

Or the location of the headphone jack?

Or the quality of its ‘Animojis’?

Probably not. I’d say it’s battery life. That’s why so many people suffer from ‘battery anxiety’, or pack a power bank when they leave home, or search for a power outlet the minute they arrive at the airport or a cafe.

The solution? Wireless charging technology that makes a phone seems like it charges itself. Technology that frees you from managing the phone battery. Maybe something like this

Tuesday, July 24, 2018

Trading off for convenience

Generally speaking:
  • Wired Internet connections deliver faster speeds than wireless ones.
  • Corded phones provides better connection reliability and better energy efficiency than mobile phones.
  • Desktop computers deliver higher performance than a notebook computers,

People are willing to trade a lot in order to gain freedom and convenience.

So yes, wired charging is faster and more energy-efficient than wireless charging. But having a phone that appears to charge itself is so much more convenient than managing your battery, looking for power outlets or carrying a power bank when you leave your home.