[sdiy] advice on creating power for small wearables? batteries ? solar ? Etc

[Roman Sowa]

Without knowing any specific features of your project, I might suggest 
using the batteries, best if this is most common model, like CR2032, or 
LR44. Users can buy them everywhere and replace in no time.

If you have some space for solar cell, then maybe 50mA Li-ion is worth 
checking. Search for "energy harvesting" chips, they contain everything 
you need to manage battery and charge it from solar cell.
But I have not yet seen a Li-ion battery that doesn't go poof in merely 
few years. You can't force users to treat the battery in proper way, 
that means never leave totally discharged for a long time.

Your worst nightmare in terms of battery drain will be the speaker, so 
maybe reconsider if it's that important.

My low power board (not important for this discussion what it does) 
draws 1mA in operation and about 6uA after auto-power-off. And still I 
recommend 4xAA cels because of their widespread availability. Which BTW 
should be replaced every 4 years or so.

Roman

W dniu 2020-10-07 o 18:43, Dan Snazelle pisze:
> Hello
> 
> I am working on a project that is quite small. I would love some advice on which coin or flat  batteries are good , small and have a decent output ..I would love to be able to drive leds, a 3.3v uprocessor, maybe a small speaker but of course AA batteries or a 9v are too big for this
> 
> another possibility is a storage battery with a solar cell that continually charges the battery—I have never tried this and once again any advice would be great.
> 
> obviously it’s possible as the Apple Watch has quite a small footprint yet is able to drive a screen and a microprocessor. i suppose a tiny dc to dc converter could help
> Too
> 
> I see other examples all over the place I’ve just never been in a position where I needed something very small and instead of going through thousands of entries online I figured I would ask the community first
> 
> 
> THANKS FOR ANY HELP
> 
> 
>   
> 
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