The Achilles Heel of the Mikroelektronika Hexiwear is its charging: the charging and USB connector are only designed for a limited number of plug-unplug cycles, and it does not have a wireless charging capability like the Apple iWatch. Until now! I have built a DIY wireless charging system for the Hexiwear 🙂 :

Wireless Qi Charging? IKEA!!!!

I have been experimenting with wireless charing for a few weeks, including building a Qi charging station using a kit from Adafruit (see “Qi Wireless Charging Transmitter with 3D Printed Enclosure“). The problem is that getting Qi charging receivers seems not to be that simple. With my research I have found that the Apple iWatch is using Qi technology, but they tweaked it in a way that it only works with the Apple chargers/receivers (see “Apple tweaked the Qi charging standard so that Apple Watch only works with its own chargers“). Interestingly, the furniture company IKEA is selling Qi transmitters and receivers (http://www.ikea.com/us/en/catalog/categories/departments/wireless_charging/). To my surprise, when I visited a nearby IKEA store yesterday, the older iPhone and Samsung Galaxy S4 (VITAHULT) Qi receivers were on sale for CHF 0.95 (about US$1): what could be wrong with buying a few of them? At this point, I should probably mention the ‘rolling eyes’ of my wife ;-).

Opening

The question is: can I use these for my projects? So I decided to open up the wireless phone cover. The cover has to plastic parts, and with a bit tweaking I was able to separate them. Insider there is the battery connector, the receiver circuit and the charging coil under a black FFDM (Flux Field Directional Material):

The FFDM is a high magnetic permeability and low energy loss material which enhances the power transfer efficiency. The FFDM can be easily removed. Under the FFDM there is the receiver coil:

Removing Coil

The coil is glued to the plastic cover with a double side adhesive tape. I used a tooth pick to carefully lift it up:

Removing Board

Same approach for the board. Removing the board was a bit more difficult, the board is very thin and I did not want to damage it. At the end, both the coil and the board were separated from the back cover:

iPhone 4/4S Receiver

The above Samsung S4 receiver is rated up to 650 mA charing current. They had the iPhone 4/4S on sale for CHF 0.95 too which can charge up to 1000 mA:

Opening that case is best from the backside:

The coil is a larger one, and the receiver electronics are shielded with a piece of FFDM (?). As the coil is too large for the Hexiwear, I’m continuinig with the Samsung S4 receiver and coil.

Attaching Power Wires

I removed the battery connector from the receiver board and soldered wires to connect the Hexiwear docking station PCB (5V and GND to the battery charging circuit):

And voilà: I’m able to charge the device 🙂 :

3D Printed Enclosure

The next step is to put everything in a 3D printed enclosure:

And is charging (not the charing icon on the Hexiwear) 🙂

IKEA Charging Station

Best of all, it works with the IKEA Qi charging station too:

Yes, that works too: 🙂

Summary

Sometimes a quick IKEA shopping can turn into something very useful outside the normal furniture world: I’m now able to use wireless Qi charging for the Hexiwear :-).

Happy Charging 🙂

PS: A big ‘thank-you’ to my wife and daughters. They fully understand what it means to have an engineering family member. Well, at least most of the time….

Links

• Qi Charging station: Qi Wireless Charging Transmitter with 3D Printed Enclosure
• Apple iWatch charger: Apple tweaked the Qi charging standard so that Apple Watch only works with its own chargers
• IKEA Wireless chargers: http://www.computerworld.com/article/2956383/mobile-wireless/review-ikea-wireless-charging-furniture-is-stylish-and-functional-but-not-without-issues.html