Phone Charging with Wi-Charge

20 February 2019

If you had to pick one application as the ‘holy grail’ of long-range wireless charging, it would probably be phone charging. Everyone has a phone. We all want to keep our phone batteries from running out. No one enjoys search for charging cables, remembering to plug in the phone, and managing the battery level.

Long-range wireless charging promises to solve this issue. It can deliver phones that appear to charge themselves, that maintain good battery level without user intervention.

One reason it might be considered a ‘holy grail’ is that it’s a difficult problem to solve. As they sometimes say in the Wi-Charge engineering department “if solving this problem was easy, we’d have marketing do it”.

It is difficult because phones need about half a Watt to operate ‘forever’ and you typically need to deliver more than a Watt to charge the battery while the phone is operating. Customers expect phones to charge at a distance, meaning that they don’t have to be very close to the power source. And, of course, everyone wants all forms of long-range wireless charging to be safe, UL tested, and compliant with all relevant government regulations.

What are the options for charging a phone using Wi-Charge technology?

Embed the wireless power receiver inside the phone

This is going to take time and collaboration from phone manufacturers, but the Wi-Charge wireless power receiver is small enough to be embedded inside a phone and can be placed ‘under the glass’. One unique advantage of the Wi-Charge technology is that because we use narrow beams of IR light, the power received practically does not decrease with increasing distance between transmitter and receiver. Thus, even a very small receiver can receive significant levels of energy.

Plug in the Wi-Charge receiver

The Wi-Charge receiver can directly deliver more than the 500 mW required to charge a phone. Whether with a micro USB, USB-C or a Lightning connector, the receiver can be plugged directly into the phone.

Embed the receiver in a phone case

The receiver can also be embedded in a phone case. The phone case would protect the phone against physical mishaps, just like a regular phone case. The receiver makes the phone case just a bit longer but provides the ability to charge it through the long-range wireless charging technology. Note that there is no requirement to have the case include a battery. It can be a completely passive case that houses the phone and the Wi-Charge receiver.

Connecting the power receiver to the phone is not as elegant as embedded the receiver inside the phone, but it’s a solution that does not require collaboration from phone manufacturers and can work with many of the phones on the market today.

Use the Wi-Charge receiver to power a Qi charger which then charges the phone

Magnetic induction (“Qi”) chargers allow contact charging of many modern phones such as those from Apple, Samsung and Google. However, these Qi chargers need to be powered and this typically means plugging them into a wall outlet.

In situations where this is not practical – such as in many tables in a coffee shop – the Wi-Charge receiver can serve as an excellent example of a bridge between tomorrow’s charging technology and today’s phone.

In this solution, the Qi pad is powered by a built-in rechargeable battery that can provide high current. The battery is, in turn, charged using the built-in Wi-Charge wireless power receiver.

This still requires placing the phone on the Qi pad, but now provides greater flexibility with regards to where the Qi pad is placed.


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