Multiple Audiomoths Failing to Record
We installed 31 audiomoths in the field. Upon collection after 2 weeks out, all audiomoths have stopped recording before collection - they recorded for a maximum of 5 days. We used 3 previously used Energizer Ultimate Lithium AA 1.5V Batteries but all had their voltage checked before deployment to ensure a voltage of 1.6+V (showing ">4.9V" in Audiomoth Configuration App). We used SanDisk Extreme 128GB SD Cards also previously used and formatted in exFAT. Audiomoths had Firmware 1.12.1.
All audiomoths had the single green flashing light when switched to custom mode when deployed (configuration text attached).
We created the Summaries via Audiomoth Configuration App for all the SD Cards. This showed that the first (and most of) error was "SD Card Write Error". The audiomoths stopped recording anything after doing 5 1KB recordings and the average voltage of the last recording was 3.7V.
Summaries also showed that battery voltage dropped…








Hi,
Can you post two of the SUMMARY.CSV files as a comparison. The AudioMoth will typically report SD card write errors in the last few recordings as the battery voltage drops. The reported battery voltage is measured before starting the recording with the battery under light load but the battery internal resistance then causes the voltage to drop during the recording and that causes the SD card write errors. The 128GB SanDisk Extreme cards have very high energy consumption at 384kHz. They consume about 3 times the energy of equivalent Kingston Canvas Select Plus cards.
From the calculated value in the app, and the comparison with the table below, 15 days is about 2700mAh which is probably about right for the rechargeable batteries. The Energizer Ultimate Lithium were probably partially discharged on deployment. The voltage measured under zero load and after a rest isn't always indicative of their true state of charge.
The table is from this application note: https://github.com/OpenAcousticDevices/Application-Notes/blob/master/A_Comparison_of_SD_Card_Energy_Consumption/A_Comparison_of_SD_Card_Energy_Consumption.pdf
Alex