Driving A6 GPRS with batteries

Hello - I am working on collecting data at a remote site and sending a text back to the office with the data. This only needs done once per day. I was planning on setting it up this way and would appreciate some feedback on overall concept and battery selection.

Arduino Nano with LED and regulator removed and in sleep mode most of the time
two pack of AAA batteries in parallel with each pack in series (4.5V) - I am still worried about current draw, do I need three packs?
A6 GPSR module to text data (spec sheet says can see peaks of 2A runs on 3.3 to 4.2V
RTC sending and alarm to wake up arduino
Relay firing when Arduino is awake to send power to the A6 since the Arduino cannot handle the load
plan on using the battery pack to power both the Arduino and the A6

There will be someone on site every couple of weeks depending on the the data sent but would rather not have to replace batteries very often.

Are these the best battery options? Should I consider an ER34615 or maybe a 3.7v LiPo. What challenges some with each of these?

Thank you,

Anthony

Any thoughts?

Anthony

In order to estimate battery lifetime, you need to know the average current draw and the battery capacity.

(battery lifetime in hours) ~ (battery capacity in mAh)/(average current draw in mA).

The most straightforward approach is to build a prototype, and once it is working perfectly (in accord with your specifications), simply let the battery run down and measure the time it takes.

Then you can buy bigger batteries if necessary.