Wet SD cards (Terminated)

[Shaggy Hiker]

I am writing some programs for use in PDA's in potentially wet environments (fish traps). I wanted to make sure that the data on the SD cards would survive immersion, so I took a card and left it in a glass of water for a day: No harm done.

That test may not have been very definitive. Tap water in a glass is not a terribly harmful environment. Somebody on this site told me about leaving a chip in a glass of orange juice for an hour (citric acid and sugars, more conductive than tap water). Now I'm thinking of more severe tests:

Flat coke (pH 1.8, so it's more acidic than stomach acid)

Washing machine: Front loader, so there would be agitation, soap, and dirty socks.

Dish Washer: Heat, pressure, soap, spaghetti sauce.


Any thoughts?

[brad jones]

Rusting of metal takes time, so short term tests may not bring up issues that may happen with longer term exposure.

Plus, isn't the PDA going to have an issue under water? Why wouldn't the PDA (and thus the card) be in an airtight container? Or, are these test in case of a leak?

Brad!

[Mike Hildner]

Curious, what PDA you using? Is it a rugged PDA?

[Shaggy Hiker]

No it isn't! I am looking at worst case scenarios. Under normal circumstances, the PDA would be protected both by being physically removed from the wet area, as well as being contained in a bag. However, I have no control over this, and it may be that no responsible person does either. Therefore, I want to find out what would happen.

The PDA would be destroyed if it was dropped into a fish trap. I expect a total loss there....except that the data might be saved, and that's what really matters.

Brad, I agree that corrosion would take time, and I certainly hope that the card would be recovered LONG before that time elapsed. However, the leads on an SD card appear to be brass or copper or something, which might not corrode either quickly or thoroughly. It's an interesting question. I might have to immerse a card for a few weeks to see what happens.

[brad jones]

This sounds like an interesting project. You might actually want to contact one of the companies that make the SD cards and see if they will work with you. I believe the fact that your data could be retained may be a 'testiment' to using SD cards and thus may make good marketing for them. That may be enough to get them to help you out a bit. Just a thought.

Brad!

[Shaggy Hiker]

I'm going to run a 64MB card through the wash this evening, and if it dies, and you happen to live in the Pacific Northwest, you can rest assured that $20 of your last electric bill paid for it.

If the card survives, it will indeed make a good testament to the physical durability of these cards, and it probably would be a good idea to talk to the company about it. I don't really need financial help with it, since the 64MB cards are so cheap these days, but anybody writing for a PDA might be interested in knowing that the data is indeed secure.

[dglienna]

i would think that as the PDA was frying out, all of the data on the SD card would also be erased. nobody knows which circuits would blow first. i'd have my doubts.

[Shaggy Hiker]

That's an interesting point, but I don't think I want to test it.

The SD card survived a trip through the washing machine. It looked all clean and nice, but it was not damaged, and the data was fine.

Now I'll run it through the dishwasher, which will add heat and some water pressure.

[Shaggy Hiker]

It is with some regret that I announce the demise of my SD card. It survived a night in a glass of water. It survived a run through a washing machine. It survived a run through a dishwasher (spraying hot water and soap), but then I put it in a pan of salt water and left it at a rolling boil for five minutes. At the end of that time, the chip looked none the worse for it, but the PDA wouldn't even recognize that there was a card in it.

Therefore, those cards can take a fantastic amount of wet abuse, and some heat, but boiling is too much for them.

I dissected the card, and it appeared fine on the inside, but there was some water present.

[Mike Hildner]

Remind me to never let you borrow my laptop :)

[Shaggy Hiker]

My laptop was stolen :( , which is a pretty effective way of losing data, too.


By the way, I'm back at it again. This time I won't boil the card, but I am going to try warm salt water. However, the basic plan is that an n of 1 is not very convincing, so I'm going to put the tongs to another one.

[grahamxyz]

I think the main problems will occur if the card in on power when it comes into contact with water.

Also maybe a PDA that takes two cards would double your chances of one surviving.

[Shaggy Hiker]

That's true, if the card is in a PDA, it may lose data whereas a card that is not in a PDA would not. However, I don't really want to test that out, it's more than my budget would be happy with.