discussion / Community Base  / 13 October 2021

Technical Difficulties Community Discussion

Hi Wildlabbers,

We're so excited to celebrate WILDLABS' new editorial series, Technical Difficulties, an exploration of conservation tech challenges, failures, and lessons learned. 

In the spirit of learning from failures and challenges in conservation tech, we've created this thread to give you a space to discuss your own experiences. Please feel free to talk about your own lessons learned, share advice, discuss the series and how the articles relate to your own work, and even ask for help with challenges you're currently facing. 

We hope this will be an active, ongoing, and supportive space on WILDLABS to open up this conversation and help us express the value of failure together as a community.

Looking forward to learning with all of you!



I'm not sure if this is the best place for this (particularly given that nobody else seems to have taken up the invitation in the OP).

I am having problems with my animal carried audio recorders.

The plan. My aim with this project is to record the feeding sounds of Koalas so as to quantify and qualify what and when the koalas are eating.

The set-up. I am recording continuous audio to micro SD card using audio boards pulled from Russian assembled Laboratory2 voice recorders (Soroka 17e). These boards have a low current draw (<1.7 mA) which allows me to power them with Lithium thionyl chloride batteries for up to 6 months using a 26500 sized cell. I have housed the battery and audio board in a PLA 3D printed collar mounted housing. Because the board relies on a micro-SD card socket and the MEMS microphone is also on the board thumbnail sized board, I cannot encase the electronics in resin. The case is exposed to the same environment as the koala although low and high temperatures are probably avoided to some degree by contact with the koala. The case has been tested as "water proof" when freshly assembled by weighing it down in a bucket of water for a day (without the electronics inside).

The problem. So far none of my deployed units have run for the expected time with the audio board swiching off prematurely, mostly due to corrosion causing an error in the electronics. In at least one case the audio membrane on the case was damaged which had allowed moisture to enter the case, but in some instances, there does not appear to have been any moisture intrusion to the case.

This had me wondering if the damaging environment was in the case itself. I have read that there is some potential outgassing from Lithium Thionyl Chloride cells although it is not entirely clear what the offending gas is. Also I guess it is possible that PLA (Poly-lactic Acid) plastics release a corrosive substance as they cure/degrade. 

Any guidance or help that anyone can give me with this would be greatly appreciated.



I have just retrieved another audio logger. This one went its deployment without a hitch. No signs of corrosion on this one. 

I'm wondering if it might just come down to how humid the air was when I closed the case?

Perhaps I will try closing the case in an air conditioned space in future.


To combat corrosion, you can try applying a conformal coating to the assembled board.  It's not like potting the board in resin, it's more like putting on a coat of paint.

There is another kind of waterproof "housing" that can be used.  Basically you put everything in a heat shrink tube and shrink it down with heat.  With the open ends, you get them hot then pinch the opening closed.  This welds the tube end shut.  Mounting holes can be punch in the extra thick joint so formed.  The whole process is simple enough to be done in the field with a heat gun.  This works with regular polyolefin as well as PVC heat shrink tube, it doesn't have to be the glue-coated sort.  

An update on my audio cases.

I tried changing a few things.

1. Changed battery brand and thus the age of the batteries I was being supplied. The Tadiran cells being supplied to me were made in 2014! Now in theory that should not matter with these cells. They have extreme shelf lives. But I ordered some Chinese Fanso cells and these were made just last year.

2. I have started using teflon adhesive tape to cover the audio 'vent' and around the neck side of the casing to increase the slip of the case and help keep the collar the right way up (GPS up, audio device down). The teflon tape does not have much pliability so I'm limited to the surfaces it can be fitted to. It does not stick to itself so I can't even wrap it in multiple layers but it does bond to PLA and the reflective tape. The teflon tape is more puncture resistant and it is naturally water dispersing. It does have different audio qualities though with a bit of a drum like reverb.

I have just retrieved a collar deployed 10 weeks ago using these two modifications. During this period the device has been exposed to 920 mm of rainfall, more than the average annual rainfall of the study site and the highest monthly total ever recorded in this part of Australia, so if the case was ever going to leak, this was going to do it! There is no evidence of water incursion in the case. There is no corrosion on the board or the battery and the recording device worked.

Of course the Russian assembled audio devices are currently off limits to me so I'm limited to the stock I currently have. If anyone is aware of an alternative board that I might use, I would love to hear about it. My requirements are: low power requirement (<2 mA), capacity to store 256 gb, small size (these ones are thumbnail sized), ability to record low frequencies (at least as low as 20 Hz). The µMoth is about four times the size and uses at least three times as much power. I have no need for the kind of processing power that the µMoth offers. I have found some chinese voice recorders that offer reasonably low power drain and small size but they have some kind of low frequency (high pass) filters built in which makes them of limited use for my project. If anyone has some suggestions I would love to hear them.