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Early shut down of devices

Hello,

I have several issues with the AudioMoth, I don't know if they are inter connected or not

The first issued I had, is some Audiomoth had recording failure, it always happened at midnight and the record were cutting short of 1 to 3 secondes (not really a big deal). Then I had 3 audiomoth that stop after 10 days(instead of 14) and when I checked it turned on again but the AudioMoth Play showed :

Now I have several audio moth which start at almost full battery but it depleted really fast and stop after 3-4 days, here is an example : And the left the first day of recording and the right the last day it recorded.

And I also had some WAV files without any data.

I am using Kingston 64GB sd card and Varta ultra lithium 1,5V battery

And here is my config :

Firmware : AudioMoth-Firmware-Basic (1.9.0)

Time zone : UTC-4

Sample rate (Hz) : 48000

Gain : Medium

Sleep duration (s) : 300

Recording duration (s) : 60

Active recording periods : 1

Recording period 1 : 00:00 - 00:00 (UTC-4)

First recording date : ----------

Last recording date : ----------

Filter : -

Trigger type : -

Threshold setting : -

Minimum trigger duration (s) : -

Enable LED : Yes

Enable low-voltage cut-off : Yes

Enable battery level indication : Yes (NiMH/LiPo voltage range)

Always require acoustic chime : No

Use daily folder for WAV files : Yes

Disable 48Hz DC blocking filter : No

Enable energy saver mode : No

Enable low gain range : No

Enable magnetic switch : No

Enable GPS time setting : No

Is the low-voltage cut-off option responsible for the early shut down of the devices?

Thank you in advance for you anwser,

Bryan

5 comments

5 Comments

Alex Rogers

Mar 14

Hi Bryan,

If you use the 'Summarise AudioMoth Files' option in the Config App it will generate a summary of the files on an SD card which makes it easier to see what is happening.

The gap at midnight is normal. The recordings are scheduled to stop and start at midnight. However, it is impossible to do this instantaneously so there is a 1 - 3 second gap while the file closes and the next one opens. If you set the recording period to 60 seconds, and the sleep duration to 240 seconds, the recordings will stay on a five-minute cycle and you won't see this gap.

Which AudioMoth hardware versions are these, and where did they come from originally?

Different SD cards have different energy requirements and the calculation is shown for a SanDisk Extreme 32GB card. However, you are seeing very quick battery discharge which I don't think could be down to the SD card. Can you confirm the exact SD card model and post a photo of the SD card.

Can you also post the summary file that the Config App generates from one of the SD cards. The empty files are the result of the low battery preventing the file from being closed correctly so this is part of the same issue. I think if all the AudioMoth are behaving the same it is most likely the SD cards or the batteries. We have never used the Varta ultra lithium batteries. Does the same issue arise with regular alkaline batteries? Alex

Alex Rogers

Mar 14

Replying to

Yes, the battery voltage drops whilst writing to the SD card due to the internal resistance of the run down battery. After repeated low-voltage events the AudioMoth will stop trying to write to the SD card and will wait flashing both LED as a warning.

The Kingston CANVAS SD Go! Plus card that we tested previously had the highest energy consumption of any card we had seen so this will definitely impact the deployment time. If the card you are using has the same performance as the Kingston CANVAS SD Go! Plus 64GB card you will only achieve about 1/3 of the calculated deployment time.

However, with the recording schedule of 60 seconds and 300 seconds sleeping, the AudioMoth should record for well over one month, so I would also suspect the batteries. The SUMMARY.CSV file shows a very rapid discharge of the battery which seems very strange. Are these new batteries? Could there be a mix of old and new ones installed in the AudioMoth?

We generally recommend using SanDisk Extreme SD cards (either 32GB or 64GB) and then either regular alkaline or rechargeable NiMH batteries - https://www.openacousticdevices.info/sd-card-guide. For very long deployments we use Energizer Lithium Ultimate batteries - https://www.openacousticdevices.info/batteries.

Edited

Bryan

Mar 15

Replying to

Thank you for this enlightment.

Yes, they were old batteries but I tested them and only kept those between 90% and 100% of energy and in the audio config app it always showed "> 4.9 V" when I first deployed them.

But taking into account the high energy consumption of the SDcard it is now clear why the audiomoth turn off earlier that expected. I will see to change the batteries and/or SDcard.

Thank you very much for your help Alex ! I wish you a lovely day !

Alex Rogers

Mar 15

Replying to

Great. The battery voltage when there is no load can be quite deceptive as they tend to recover their voltage but then discharge again very quickly with subsequent loading. A different SD card should solve the problem of the shorter than expected deployments.