Moteino RFM69: Battery Selection

[livesource]

Hello,

I'm starting my first moteino/arduino project - logging of temperature data every 10 mins, in a remote outdoor location. My question is what battery would be best to power the moteino rfm69 with thermistor?

My battery requirements are:

1. Small (like 9v battery size OR 2xAA size.
2. Easy to disconnect and take offsite to recharge with a common charger (usb or AA charger, for instance)
3. Resonably cheap but also descent capacity, would be great if they could last months in the field.

I'm looking these lithium AAs https://www.jaycar.co.nz/spare-li-ion-protected-26650-3-7v-3400mah-battery-for-st3498-and-st3499/p/ST3497

They seem perfect, except they have a discharging cut off voltage of 3v - is this a problem? What happens when the input voltage to the moteino drops below 3.3v? I'm reading forums and getting confused, can someone give me a clear answer on whether the moteino will still function properly down to 3v?

I am also looking at low power/sleep libraries.

Thanks all !

[TomWS]

The short answer is, depending on your sample rate, you can easily power a Node with RFM69 radio and a good thermistor design for well over 2years on two Everready Ultra lithium AA batteries.  How to do it is in this forum.

[james_s]

I like using a CR123A cell, they are 3V which is enough if you bypass the regulator by powering the 3.3v point. A pair of AA or AAA cells also works well. If you want rechargeable a single prismatic LiPo cell or 18650 should work well with the onboard regulator. You won't deplete the cell 100% before the voltage out of the regulator starts to sag but in practice that shouldn't really matter.

[Felix]

I like using a CR123A cell, they are 3V which is enough if you bypass the regulator by powering the 3.3v point.

I would not recommend hooking up power to the back of the LDO, at 3V it won't damage anything but battery life will suffer. At higher voltages damage is likely.
Instead there is the Moteino-8mhz that can run from 3.6V down well below 3V so it's ideal for even lower power consumption of single 3V cells or double AA batteries that can be used to depletion.

[james_s]

I just omitted the regulator on the Moteinos I built for 3V operation. The regulator can also be removed from the standard one.