power arduino w/shield and sensors with AA battery

Hi, my project involves internet and sd datalog, I want to place it outdoor where without ac socket. I tried to connect a 9v battery but it crashed within half an hour.So would it be better if it is hooked up with 4x AA rechargeable battery? or any alternative way?

Thank you!

You need to work out the necessary battery capacity. Find out the average current draw (measure with a multimeter ?), decide how long you want to run it for and compute the minimum battery capacity.

Capacity = current x time.

Normally we use amps and hours or milliamps and hours - thus the units are either Ah (ampere-hour) or mAh (milliampere-hour). Rechargable batteries should have a capacity spec, often printed on the battery.

But note the marked capacity is only true for a brand new battery that's correctly and fully charged and discharged at the 10-hour rate - in other words add a healthy safety margin (50 to 100% - battery capacity reduces with age and use).

So for instance an 80mA load for 2 days = 80mA x 48h = 3840mAh (3.84Ah). A 5Ah or 7Ah battery would work for this case.

[ note AA rechargables are in the 1.5 to 2.2Ah range, typically - for more capacity C and D-size cells may be needed, or a SLA battery ]