Charging the Puck.js wirelessly with QI wireless charger

Would it be possible to charge the Puck.js with a QI wireless charger?

Maybe using a LI2032 connected to corresponding charging coil.

Maybe it would be easier, to use a custom coil instead of QI.

Would these coils (https://www.adafruit.com/product/1459) work? Which type of rechargeable battery should I use with the Puck.js?

...if the Puck built-in NFC coil would be 'switchable' between antenna - as it is right now - and between transfer/charging coil - the new feature - that would be great...

There is still some active circuitry needed, because because pass-filters cannot do the job... except they may be switchable. I have no knowledge about the frequencies such charging applications use.

Puck Built-In Micro Energy Harvesting... a next thing? ( @Gordon? )

You couldn't do it without some modifications I'm afraid - as @allObjects says there isn't the hardware in the chip to handle wireless charging.

I wouldn't suggest it I'm afraid - there are a few things you'd need to look out for:

• LI2032 batteries can be at 4.2v when being charged, but Puck.js maxes out at 3.6v - so you'd need a voltage regulator (or a diode to drop the voltage).
  
• I'm not sure how the existing NFC coil would cope with the power being sent to the separate coil - it'd definitely pick some of it up, and it could damage the nRF52 module
  
• Physically you might have trouble fitting the charger board into the existing casing
  
  

You could potentially cut the NFC tracks that lead to the nRF52 module, then add a full bridge rectifier to the existing coil - along with a diode to drop the voltage from the battery - but it's turning into a pretty serious modification.

I should have a small Bluetooth LE board available soon (rather than the cased Puck.js), and it'd probably make more sense to try something with that instead?

@Gordon thank you for the detailed reply.

I should have a small Bluetooth LE board available soon (rather than the cased Puck.js), and it'd probably make more sense to try something with that instead?

Sounds great. Do you know when it will approximately be available?

My guess is around April 2018 - although hopefully before.

Is there any information about the upcoming board available online?

Will it include also the MAG3110 Magnetometer of the Puck.js?

There's a very long-winded thread with some stuff on it here: http://forum.espruino.com/conversations/­310122/

But the plan is for a small, very basic board with just the BLE module and a voltage regulator. - and trying to keep it as affordable as possible. Having played around with some prototypes I'm probably going to revise that to include a button and LED, but there wouldn't be a magnetometer.

Having said that, the 0.1" pinout would make it trivial to add whatever other modules (magnetometer, gyro, etc) you wanted - most have such low power consumption you can power them off the GPIO, so you could just solder something like this directly to the side.