MDBT42Q on coin cell

Sun 2018.11.25

Let's check the data sheets.

The load:

http://www.espruino.com/MDBT42Q

2.5 - 16v voltage input, 20uA power draw when advertising

Note the caution: Do NOT get the polarity wrong
Also see note beneath heading 'Bare Module' about battery selection

The supply:

http://data.energizer.com/pdfs/cr1225.pdf

From the graph, ~600 hrs @ 60uA

Number of hours in a month ~720

While just advertising, under ideal conditions, at room temperature, expect no more than 3 months of continuous use with no additional hardware attached and no LED's illuminated. Mileage may vary. I'd be more worried about what the other interface hardware load requirements were, then select the power supply.

Might be able to play with (following link) to extend that some:

http://www.espruino.com/Reference#l_NRF_setConnectionInterval