Qi charging is awesome, can push a lot of power from the sender to the receiver, enough to quite rapidly charge a mobile phone. I do however find the circuits to be very advanced and involve a lot of components.

I am looking to make a small device with a small lir2032 battery wirelessly chargeable. Size is very constrained and I want to keep the number of components to a minimum and all that power Qi charging can deliver cannot be put to use in this small device anyway.

So I am wondering if I can take a shortcut.

The first thing that came to mind was to use a standard Qi charger and receive the power with a coil. It seems Qi chargers will send a pulse every 1 second. I wonder if this pulse would be enough to charge this small battery if left overnight. Tried to find some info regarding this handshake. I guess I would need to know the duty cycle and how many mA it would transmit. What is the duty cycle and how much power can I collect?

Second thing I thought about was if there was something in the Qi standard so that I could in a simple way ramp it up to one of the lower mA modes. But I guess there is not?

Is any of these thoughts doable, or do I need to implement some kind of feedback channel for Qi?



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