Figure out power requirements and choose battery

[securelyfitz]

Badge has pads for both cr2032 and aaa holders. boost regulator will work fine with either, and will mean either battery's full capacity can be used.

Need to determine:

• screen off power consumption
• screen on power consumption
• transmitting power consumption

Goal is to work for the whole event = 48 hours. estimate based on: 1 h of screen on 47 h of screen off 500 transmissions

CR2032 has ~235 mah @ 3v nominal, 2v dead, 1.5v average = 587mWh (duracell says 745 mWh nominal) aaa has 800 to 1200 mah * 1.5v nominal; 1200-1800 mwh nominal or likely 800 to 1200 mwh in practice - 2x a coin cell?

that gives a power budget of 10mW on coin cell or 20mW on AAA. Based on rp2040 datasheet this is theoretically possible.

If it's close, some ways to improve:

• change R10 to limit IR led current
• adjust timeouts
• minimize display usage
• reduce rp2040 clock speed (though this makes operations take longer and maybe more total power)

[securelyfitz]

Decision: Stick with AAA.

bare board: 40mw circuitpython running, screen off: 100mw circuitpython running, screen on: 200mw IRDA doesn't noticeably affect power consumption.

should be feasible to get low power states working and still fit within the idle power consumption, but it looks like AAA is essential, and even then we should have spares just in case.