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AudioMoths stop recording after about 3050 files

Greetings to the AM support community,

I am new to the game and am wondering if someone can help with my units failing to record after about a week. I recently deployed 4 brand new units with a recording schedule of 50 sec on 10 sec off for three hours in the morning and evening. The units were deployed with 64GB micro SD cards and 3, 2800mAh rechargable batteries. After about 3 weeks we collected them, and found that all 4 had stopped recording 9 days into deployment, amassing between 3,040-3,090 files per unit. After checking the properties of the SD cards I found that all four had used about 13.7GB of space and had 45.7 GB of free space left. After double checking the configuration report, the daily energy consumption should have been 65 mAh (2800/65=43 days, right?). The batteries weren't necessarily new, but if that was the issue it surprises me that there wouldn't be more duration variability across units since we use a mix of brand new and gently used batteries for all four of them. But they all stopped recording on the same day, give or take a few hours.

Luckily these deployments are just for collecting sample calls, but I need to sort this out before we start deploying for long-term monitoring. Any ideas what might be going on? Thanks!

4 comments

4 Comments

Kaeli Swift

May 29

And here is the summary CSV. We are using SanDisk Extreme V30 microsd cards

Alex Rogers

May 29

Replying to

Hi Kaeli,

It looks like the batteries went flat. You can see the voltage dropping very rapidly at the end of their life.

The battery dropped low enough to start causing SD card write errors, and then the AudioMoth cancelled the recordings after five failed attempts.

Recorded at 19:28:00 29/04/2025 (UTC) by AudioMoth 249C600164F37077 at medium gain while battery was 3.0V and temperature was 31.2C. Recording stopped due to SD card write error.

Note that the SUMMARY.CSV file show 50 seconds records, rather than 10 second recordings in the CONFIG.TXT. The calculated energy consumption should be just 65mAh per day which should be good for over 40 days - 2800 mAh / 65 mAh/day = 43 days. What type of rechargeable batteries were you using? The initial voltage is quite low 3.8 / 3.9 V and fully charged rechargeable batteries would typically be closer to 4.2V at the start. The bigget source of consumption variance is typically the SD card. SanDisk Extreme cards are generally very reliable and low-energy. Can you check on the back of one of the cards to see where is was made. Should say 'Made in China' or 'Made in Malaysia'.

Kaeli Swift

May 29

Hi Alex, I don't have the exact config text file from the specific failed recordings, but I generated one with with the same schedule (this was a good reminder to keep the config text file with the data moving forward-thank you for that).

Alex Rogers

May 12

Hi Kaeli, Can you use the 'Summarise AudioMoth' files option under the 'Process' menu option in the Config App to generate a summary of the SD card contents and post that here with the CONFIG.TXT file. This will show the battery voltage on each recording (it is also in the WAV file header which you can see in the AudioMoth Play tool - https://play.openacousticdevices.info). What make and model of SD card are you using. Most often variation in energy consumption is due to the SD card.

Alex