I am testing some methods to extend the battery life of the audiomoth.
I have successfully powered the audiomoth using a battery pack that holds 8 AAs instead of 3 AAs, but the extra batteries did not extend the life of the audiomoth.
I ran two tests - first I used the standard 3 AA battery pack that comes with the audiomoth and let it record continuously until the batteries ran out. Then I switched to the 8 AA battery pack and repeated the test with identical settings. In both cases the audiomoth ran for 8 days before the files started being clipped (after 8 days the files lengths got progressively shorter and listed "Recording cancelled before completion due to low battery voltage" in the comments section).
Strangely, with the 8 AA battery pack the unit stayed above 4.9V even after it started clipping files "due to low battery voltage"
I had expected the extra batteries would let the audiomoth run 2-3 times longer. I'm not sure why that wasn't the case.