problem powering an arduino pro mini (5v version) with a coin cell(cr2032)

I'm having problem while powering an arduino pro mini (5v,16MHz) with a single cr2032 3v coin cell(nominal capacity :236mAh).

The pro mini which i have draws nearly 24mA when awake and 4mA in sleep mode .
I tried connecting the battery to a 5v step up regulator t ( Pololu 5V Step-Up Voltage Regulator U1V10F5 )to step up the voltage from 3v to 5v but for some reason the arduino worked only for nearly 5 seconds and the stopped working .The arduino woks very well with a 9v battery, but for my project size ,weight is a limiting factor.

can anyone help

Please watch the cell voltage with a voltmeter when running.

The cell voltage drops to 2.1v after few second when connected to the arduino and then when it is reconnected to the arduino (after disconnecting it )again runs for few seconds and then again shuts down

Tanish_shet:
The cell voltage drops to 2.1v after few second when connected to the arduino and then when it is reconnected to the arduino (after disconnecting it )again runs for few seconds and then again shuts down

Sounds about right.

Most all of the CR2032 datasheets I have looked at suggest they are good for only a couple of mA or so.

So when you try to draw 50mA or more, to step up 3V @ 24mA to 5V, you might expect the battery to die .......

Should have tried with a 3.3volt (8Mhz) board.
16Mhz requires a minimum VCC of 3.85volt for reliable operation of a 328 processor.
I expect it to be about the same for the processor of a ProMini.
Leo..

Remove the voltage regulator and power LED from the Pro Mini using your solder pencil, and use the internal 8 MHz RC clock, if running on 3V. Then it should run as expected and draw negligible current in sleep mode.

The thing is i have permanently soldered another pcb over the arduino with the help of stackable headers and removing the LED is not possible .
Instead can increasing the sleep time so that the battery voltage stabilises be of any help.And also i will slow down clock frequency using the CLKPR function(and run the arduino at a 8MHz or 4MHz frequency) to bring down the current draw

The thing is i have permanently soldered another pcb over the arduino

For USD $2, start over and do it correctly.

Tanish_shet:
The thing is i have permanently soldered another PCB over the Arduino with the help of stackable headers and removing the LED is not possible .

That's OK. Just use a "phone charger" as a power supply at 5 V, plug it into a power point and you will have no such problem.

That power LED draws about 4 mA... no way around it.
The regulator wastes much less but still wastes some.

Would soldering a 100uf capacitor in parallel to the cell be helpful.Also would it better if i ditch the 5v step regulator.

Thanks to all for the replies :slight_smile:

Get a 3.3V Pro Mini, remove the regulator & LED, ditch that boost regulator. Then you have a fair chance to run it for a reasonable time on a coin battery.

Would soldering a 100uf capacitor in parallel to the cell be helpful.

No

If you are limited by weight but can tolerate short run time try 3 or 4 alkaline coin cells. Or consider the hearing aids zinc air batteries.