©2019 Open Acoustic Devices

Aug 8

Configuring date start time?

8 comments

Is it possible to configure the AudioMoth to begin recording set time intervals on a specific start date? If not I would love to see this in a future update as it would make project logistics much easier when utilizing multiple units in various locations!

 

Yes, this will be in the next main release of the firmware which should be out in October.

For my application, it would be great to be able to set an recording scheme, where the device "sleeps" for some days and then starts recording for one or two etc. days (with a defined daytime scheme like it can be set in the app) and then sleeping again for the defined number of days. Would this maybe be possible to include in the next firmware? Or does this require specific "hard coding"? Thank you, Mr. Rogers, for answering to all those single questions here!

Thank you Alex,

 

I had the exact same question after deploying over 150 AudioMoths this summer. I did a terrible job of calculating battery life, and learned that even with lithium batteries the Audiomoths were dying in the field months before I anticipated going back to them. This feature should really help address that issue, because we could place multiple AudioMoths in the same location and have them turn on in sequence as the batteries in the preceeding AudioMoth die. It will also allow field researchers to deploy many AudioMoths over several weeks or more in a more logistically feasible manner and then have data collection begin simultaneously.

 

On a related note, is there a different way to display battery usage, or somehow estimate how long batteries will last given a particular configuration? I appreciate the information regarding the number of mAh per day, but I don't really know how to translate that into something that corresponds with how many days I can expect with 3 AA batteries. In my situation I calculated 3 * 3000mAh (size of each Lithium Ion battery) = 9000 mAh. I thought this might give me something approaching 100 days at 8 hours of recording per day, but all of my AudioMoths died around 30-33 days. I am assuming that there must be more to that calculation than what I did, but I could not find any information on how to calculate battery life expectancy at a given use rate.

Hi Trent, We only display the energy consumption of AudioMoth in terms of mAh since the actual lifetime will depend on the details of the batteries that are used.

 

The minimum voltage acceptable input voltage is about 3.6V which corresponds to 1.2V per cell.

 

The Energizer Ultimate Lithium batteries are very good as they generally stay about 1.2V over their entire lifetime. The plot at the bottom of the data sheet shows the discharge curve of the battery and shows that it should provide the full 3600mAh before the battery goes below 1.2V - http://data.energizer.com/pdfs/l91.pdf.

 

 

 

 

The discharge curve for alkaline batteries is much steeper. Below is the one for Duracell batteries. It has different units but if you take the cutoff voltage as 1.2V and multiply the hours of service life by the discharge rate, you get about a capacity of about 2200mAh.

 

 

 

However, when you combine the batteries together in AudioMoth you are putting them in series. This means that the three 1.5V batteries together give a 4.5V battery but with a capacity still equal to 3600mAh (since the same current flows through each battery). That's why your AudioMoth stopped recording after about 1/3 of the duration you expected.

 

Alex

Here's the plot for the Energizer Ultimate Lithium batteries.

 

 

 

Hi! I'm new to AM but already have this same problem. We've just purchased 20 AM (firmware <1.2.0) and as long as I can see, we can't set up a starting date. Has this been developed already? Is it going to be available for our devices? Thanks so much!

7 hours ago

Hi, This will be in the next big release of the firmware early next year. All the versions of the firmware are compatible with all versions of the hardware so you can updated to the current firmware (which supports large exFAT formatted SD cards) now, or wait for the next release. Alex

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