Another quick search and somebody suffered your pain in 2011 :P

http://interactive-matter.eu/blog/2009/08/29/driving-circuits-from-a-cr2032-lithium-coin-cell#comment-5748

I'm a fan of AAA power, since they're cheap and rechargeable options, but what about other options:

- Parallel CR2032
- Rechargeable coin cell http://www.digikey.com/product-detail/en/ML2430-CJ1/SY615-ND/3662229

Changing the microsd storage by flash storage don't improve the situation, because they also typically eat 10-15ma when writing :S

On Thu, Apr 9, 2015 at 10:12 AM, Werner Almesberger <werner@almesberger.net> wrote:
Felix wrote:
> I was curious about that and find some data on stackoverflow:
> http://electronics.stackexchange.com/questions/37173/low-power-micro-sd-card-storage/123386#123386

Ah, nice ! Pity he didn't have a better meter that would let him
monitor also the short peaks.

> it seems that you would need a ¡50mf one!

Yeah, I ended up with this sort of monsters, too :-)

Now, there would be fairly small and not too expensive supercaps
in that range. However, they have an even worse ESR (Equivalent
Series Resistance) than the coin cell: about 15-20 Ohm for the
cell, about 100 Ohm for a compact supercap, so they couldn't
deliver nearly enough current.

However, I also found supercaps with a low ESR. But they're quite
large and pretty expensive. Here is a 50 mF model with a stunning
100 mOhm:
http://www.digikey.com/product-detail/en/BZ013B503ZSB/478-3521-ND/1014116

That's when I decided that this is probably not where I'll find a
solution ...

- Werner

_______________________________________________
Qi Hardware Discussion List
Mail to list (members only): discussion@lists.en.qi-hardware.com
Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion



--
Felix