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

[Brian Willoughby]

The battery technology is certainly a significant concern.

However, I'd like to point out that the way you design the rest of the circuit - with regard to the amount of power draw - is equally important. Don't stop with the battery choice.

Processors like the Texas Instruments MSP430 can run on pico amps of power. There are other options, but if you want something to run a long time without recharging - no matter what size battery - then it pays to put some thought into the processor selection. They don't automatically draw less power; you also have to write the firmware so that unused features in the chip are shut down until they're needed.

Besides the processor, you can find LED options that are more efficient than others. You might consider toning down the ridiculous brightness that modern devices seem to favor, and instead consume less energy. This can be challenging, though. I worked with one LED that would only work in "too bright" mode. When I dropped the current below a certain point, the LED simply wouldn't turn on. In that case, I had to select a different LED that wasn't super bright.

Brian


On Oct 7, 2020, at 9:43 AM, Dan Snazelle <subjectivity at hotmail.com> wrote:
> 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