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AudioMoth Recordings Stopped Before Expected Lifespan

Greetings,

I deployed units with the hope to leave them unattended in the field for months before swapping batteries. When I configured the unit, it estimated energy consumption at 16 mAh a day and produce 120 files totalling 518 MB (recording for a 2 hour window each day, 45 sec recordings with 15 second sleep between).

With a 64 GB card, I was expecting 110+ days of recording, but it seems the 3 AA batteries died after just 42 days on. Is this the appropriate battery life or should I have expected more? Was my estimation way off? How do you estimate battery lifespan from the information given?

I am in SE Georgia where it is extremely hot and humid but units were placed in shady areas to help keep the unit cooler.

9 comments

9 Comments

Alex Rogers

Jul 18

Hi,

Can you confirm which SD cards you are using? The values in the Config App are calculated assuming 32GB SanDisk Extreme cards. Other SD cards have varying energy consumption and this is normally the source of different lifetimes. https://www.openacousticdevices.info/sd-card-guide Can you use the 'Summarise AudioMoth Files' option in the Config App to generate a SUMMARY.CSV file from one of the SD cards. This will show the battery voltage over time. What make and model batteries were you using? Alex

Alex Rogers

Jul 18

Replying to

Where did this AudioMoth come from and how old is it? It's possible that the humidity affected the energy consumption, but I wouldn't have expected it to. Were the batteries from a good supplier? I'll reproduce this configuration and double check the consumption on one of my AudioMoth.

Edited

sarah.manning

Jul 18

Replying to

I ordered 15 units and cases from LabMaker and received it in May 2024, this was their first use. The one other unit I've checked had very similar results. The batteries were ordered from Amazon and supplied by a third party...

Alex Rogers

Jul 19

Replying to

I measured the energy consumption of your configuration with a SanDisk Extreme 64GB card and it matches the Config App estimate - about 20mAh per day given the larger card. This is very little energy so I'm surprised that the batteries depleted so quickly. It might be worth sending one of the devices that exhibited this behaviour to andy@openacousticdevices.info to double-check. However, I think it would be unlikely to be the AudioMoth itself. I would be more suspicious of the batteries. If you have any of the batteries as received, you could try a more energy-intensive configuration such as making 24 one-hour 384kHz recordings per day (use 00:00 - 00:00 recording schedule and 59:55s recording with 5s sleep). That should use the same energy as your original configuration within a single day. Compare that against fully charged NiMH batteries or alternative good quality alkaline batteries such as Duracell.

Edited