Thank you for these suggestions! I forwarded them to our IT person, and he is looking into it. I took some copies of the recovered files home, on a hunch, and took a look on my Mac (I have a PC laptop at work...) Sure enough, I can see the original recording dates and times (all metadata) for the wave files just fine under properties/info on my Mac. So now we know the original info is still there, and attached to each file.

Thanks for the info, davidlee!

Our IT person was able to recover all of the files, but after reviewing them, I see some issues. The actual files look good, are the correct length and size (for the most part), and sound like "good" audio files. The files have been renamed and no longer retain any of the date time info of the originals, unfortunately. I tried all ways I know to locate that time/date info, and no luck. Let me know if you have any tricks... I can't tell what order they are in, or if they are from this year or previous years. Since I re-used cards each year, I don't know if the app restored all the old files as well (I have seen this when restoring files in the past), even though I reformat cards before deploying (which theoretically should erase anything prior to the format date completely). I listened to many files trying to see if I could bracket manually the deployment window. I was able to, but got the strong feeling some files were from previous years, etc., since I actually hear what sounds like several deployment and retrieval events. I found files the usual 5 min long, and others were 10 min, suggesting old files (we did some 10 min in 2021, 2022), or other issues. I "think" I can tell which ones are this year's and previous years, by the characteristics of the file, but those are guesses. I am also guessing, but think the files are in order within year, but the group of this year's files are at the top, followed by the files from previous years... So we will review these a bit more in our team, but may not be able to use them.

Ok, I am hopeful and will post my results.

When I insert the card in my reader, the drive icon pops up in the window under Devices and Drives, but when I click on it, it works away, and stops or I get a pip-up saying insert a disk or drive. I have tried multiple readers, and computers. Our IT guy has some recovery software he wants to try on Wednesday, so we will see what that can do. I also think I might be able to try Sandisk's Rescuepro software offer that comes free with the cards.

Thanks for the replies. David when you say it will identify failing cells, how does it show that, what does that look like? Here is the charger we are using: Amazon.com: XTAR VC8 Plus Fast LCD Display Rechargeable Battery Charger with DC36W Adapter max 3A 1 Slots/8 Slots 1A Fast Charge 10400 14500 18650 20700 21700 26650 or AA AAA LI-ION 1.2V Ni-MH Ni-Cd : Electronics Alex, I placed one battery retrieved from an ARU, reading 0.06 volts (err on the charger) in series with two new never deployed batteries, both reading 1.26 volts, and the reading is 2.59 volts. My current working theory is that when I used these batteries the first year, I over discharged many of them, and damaged them. When I recharged them prior to this year's deployment, they took the full charge (looked ok, no err message) but then in the field could not hold it very long, and that pulled the overall voltage down so much that if there was "good" battery in the group of three, there was still not enough voltage to meet the minimum ~3.6 volts needed to record the sound files. I am leaning toward being safe next year, and just biting the bullet and using only the Energizer Ultimate Lithium. They are not rechargeable, but I did find a local place that will recycle them