For you b4r guys and gals

It fits in a AA battery holder.
http://makezine.com/2016/04/24/meet-arduino-clone-thats-size-aa-battery/

Anyone have any idea how long the batteries would last in a thing like this?

And in thinking about when I was a Electronic tech I worked on pagers. Anyway one thing they did do to prolong battery life was strobe or basically turn off part of the electronics for a few milla-seconds and then back on. It really extended battery life. Aaaahhhhh... Quite a few x-wives ago.

If the above size is ok to you, you could use much stronger batteries & a power regulator. Should last 1-2 years, maybe more

I love it, but 3 volts of alkaline cells may be pretty marginal for running 3.3v circuits. The alkaline AAs' voltages will probably quickly fall below the usable threshold, meaning that they'll effectively be "dead"while still containing 80% or more of their charge.

It seems like a pair of alkaline 9v batteries in parallel would be a far longer-life alternative, even using a power-wasting linear regulator. Or maybe use a pair of discharge-protected lithium-ion cells and a regulator instead?

Neat idea though, nonethless.

JakeBullet70 said:

Anyone have any idea how long the batteries would last in a thing like this?

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You could put a multimeter in series with the battery to determine the current draw of the circuit. Put the multimeter on 500ma to 1 amp and if the meter shows a 50ma draw and the AA battery is rated at 2100 mah, then you're looking at APPROXIMATELY 2100/50 = 40 hours. I say approximately because your mileage may vary. Rechargeable batteries like NiMH may last longer than alkaline depending on the power draw.

And of course a 6 volt lantern battery would run it for much longer period of time.

JakeBullet70 said:

Anyone have any idea how long the batteries would last in a thing like this?

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Total battery life will depend "mostly" on radio ON/OFF ratio, assuming that the rest is neglictible. I suppose that there also low-power states for the arduinos
The RFM96 of the pìcture can draw up to 100mA when transmitting, about 10mA when in receive mode, and only 1uA when in Sleep mode. So,if the module is put to SLEEP and wake up every 60sec (this can be programmed through SPI registers), transmit for 0.5 seconds and sleep again, battery life will increase a lot.

I am using a RFM95 (868MHz) with a 3V3 cell coin, working as a receiver most of the time. There are some problems, one of them is that battery voltage instantly falls al 2.8V when connected to the circuit and general power consumption is still too high, so now I am developing the part where both micro and radio module go to sleep and wake up periodically with a timer, so that battery lasts as much as possible.

JordiCP said:

The RFM96 of the pìcture can draw up to 100mA when transmitting, about 10mA when in receive mode, and only 1uA when in Sleep mode. So,if the module is put to SLEEP and wake up every 60sec (this can be programmed through SPI registers), transmit for 0.5 seconds and sleep again, battery life will increase a lot

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Ahhhh, OK then they can do a battery save mode.

JordiCP said:

so now I am developing the part where both micro and radio module go to sleep and wake up periodically with a timer, so that battery lasts as much as possible.

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Please keep us informed of this.

The reason I ask about battery save mode is the wired VS un-wired debate.

In fact, the module can be programmed in different modes, being the sleep mode for battery save during no-activity periods. It is the micro the one who is in charge to wake up everything at regular intervals.

JakeBullet70 said:

Please keep us informed of this.

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I will, even though but it is not an arduino project, in this case I am using a Renesas microcontroller