No Battery Microcontroller Operation - (Motion, heat, induction etc) I am using an ATtiny85 to sleep for a long period of time, collect some data, send it over radio, and go back to sleep, after disabling everything possible. The ATtiny is currently powered by a coin cell. I can get quite some time off that coin cell, but it's simply not enough, and the coin cell cannot be changed once the board is deployed. Peak current draw is around 10-15 mA.

My aim here is to find an alternative power source for my board. Some good news is that the boards are never more than one or two feet from a receiver, so rf-like power transmission may be possible. Some other options may be motion or heat (it's a wearable device). The amount of power could be pretty small, as I only need it at peak periods, so I could just charge up a supercapacitor for a while and drain it when power is needed after the Attiny wakes up for less than a second.

The ideal situation would be to have a means of power transmission or generation that provides enough current to continuously power the microcontroller without the need for sleep, but I recognize that this is probably not feasible. However, due to the limited range it might be. Another concern is radiation to the wearer.

If anyone has any experience in this kind of power transmission or generation or just any ideas I would love to hear it. Thanks!
10mA is quite a lot for a coin cell. And of course the duration is really low.

As for wireless power transmission, I highly discourage you. Since you are using coin cell batteries I think that size is a must for you, and for wireless power you will need a really big antenna. If it is a wearable I think that the receiver is on the body too, and so much power is not a good thing.

In my opinion and according to my experience you have two possibilities:


use alkaline batteries (e.g. AAA). Use a step up driver to get 3.3V from 1.5V (since the current you need is low you can use simple charge pump regulators, so with a 10pin TSSOP integrate and three small capacitors you are done) and you will get a really long lasting circuit. Drawback: AAA batteries are a bit large, so probably you'll have to make a bigger receiver
use lithium batteries (usually I use LiPo). You will then be able to recharge the battery with any power supply (I usually use an IC which can charge LiPos with a 5V source - USB - and a couple of other components (two capacitors and a LED with its resistor).


Personally I struggled with coin cells for a long time before giving up and sticking with lipos forever.