I have 13 adafruit LED sequins in parallel hooked up to a CR2032 coin cell. This cell is also hooked up to an adafruit Gemma board (Arduino-like board using an Attiny85). Pads D0 & D1 on the Gemma each connect to a single LED sequin. D0 & D1 can do PWM, so the Gemma's program simply fades these two LEDs on and off. This is all connected using conductive steel thread.
When I use the coin cell, the 13 LEDs all light up like I would expect, but the Gemma stays dark (it has a green LED to indicate when it's powered up). When I power the Gemma via USB, it works as expected: the two LEDs connected to the PWM pads fade on and off, while the rest of the LEDs stay on.
What is the problem with my coin cell power source? Not enough voltage? Not enough current? Could I fix it by putting two of these cells together?
Note that the LED sequins each have their own 220 ohm resistor, and when "powered from 3.3V they draw about 5mA". The Gemma "draws only 9 mA while running" and has an "On-board 3.3V power regulator with 150mA output capability"