Thursday, October 30, 2014

Wireless chargign

I am tired of plugging the charger in my phone. And I'm afraid the socket is going to break soon, seeing as it's about the fourth cable that has broken on me..
So as a solution I ordered a QI wireless charging set. A Note II receiver that claims to have charging current of 500-1000mA at 5V, works up to 5mm from the reciver at the frequency of 100-200kHz with efficiency of more than 70%.

I also bought 2 transmitters. One nice round plastic disk and the other one a bare PCB with a coil.
They both take an input of 1500mA at 5V and claim a 75% conversion efficiency.

And the other one:

The coils are made of strands of coated wire that are about 0.05mm(45AWG). The whole cable is ~1mm in diameter. That's about 300 strands!
It's stranded to increase the surface area to transmit more power.
Unfortunately the receiver's coil is just a copper track on a flex PCB. And has some surface area but not as much.

The charging rate is just average. Gets 460mA through. Not as claimed but good enough, falls in the 70% of 500mA. (The phone is claimed to charge at up to 2A!)