If you have sealed devices in silicone for weatherproofing, have they ever ruptured or died due to it?


(Mike) #1

Hi folks,

Someone here (okay, @JDRoberts :wink:) said, “Batteries outgas, and consequently unless the Device is specifically designed to operate in an airtight container, it’s not a good idea to weatherproof it to that extent.”

This is news to me and seems improbable, but I haven’t sealed any devices yet. So let’s have a poll.

If you have sealed a device in silicone or something similar, have you ever seen a problem from outgassing? Rupturing or exploding? Or maybe it died young, you opened it, and found it had some kind of weird stain or fried look inside that might be due to harmful gas deposition?

Of course, I am talking about typical smart-home devices used with SmartThings. You are welcome to speak about other things you’ve seen, but clarify if it wasn’t from a smart-home device.

And please chime in if you have seen it or if you haven’t seen it. Because even if it has happened, it still says a lot if it only happened for a few out of many. If we are going to get a consensus, we need the positives and the negatives.

Please say what type of devices, how long they’ve been sealed, and with what.

I’m not trying to raise a ruckus. It’s just an honest question. Looking for real-world experiences.

Thanks all!

Edit:
@JDRoberts, that’s a good point, I should have made an option so folks who are sure they shouldn’t (so they didn’t) could also chime in. Just so we all get that input, too. But it will not let me edit a poll after the first five minutes. Also in hindsight it might have been smarter to simply ask if anyone has had ANY problem (or not) due to sealing their device. If anyone wants to consider this a vote on sealing (not necessarily outgassing per se), please vote on sealing problems in general (yay or nay).

It’s the first time I’ve made a poll… kind of fun!

  • Yes, I’ve clearly seen a sealed outgas problem with one or more of my devices
  • Yes, I think had an outgas problem, but I’m not certain
  • Maybe I had an outgas problem; can’t be sure
  • No, I’ve used a sealed device at least a few months with no problem
  • No, I’ve had many sealed devices a long while with no problem

0 voters


( I hate Mondays) #2

I have improvised a poor man’s insulation device for a contact sensor in a wooden gate - used. 1/2 wood spade drill and drilled a few holes to form a rounded rectangle roughly the shape of the Iris contact sensor. Put the sensor in a snack ziploc bag (hell yeah lol) and pushed the air out of the bag, zipping it up. Then I wrapped the bag around the sensor and shoved it into the drilled hole. Did that about a year ago. I occasionally replace the bag after a few battery changes, simply because I have bags in excess LOL

My patio screen contact sensors are wrapped in kitchen cling wrap then taped around the edge once, then front to bottom once, then taped with double tape to the screen door frame. In the rain, never a problem, have not rusted on the inside, never found water in them. Gas? Hmpff…


How to seal (weatherproof) a sensor device... anything better than silicone?
#3

The “someone” is me, I was a network engineer, I have a degree in computer information systems, I took courses in sensor design, and I read UL specifications for a living. :wink:

Do whatever you want to do, but I still recommend contacting the manufacturer of the device you’re considering weatherproofing and see what they have to say. If what you’re going to do doesn’t void your warranty, more power to you. If it does, that’s a decision you have to make for yourself. But you might as well get expert information from the source. :sunglasses:

BTW, your poll is missing one important choice:

“I don’t weatherproof my devices in any way that would void the warranty, so the question is not applicable to my experience.”.

Just sayin’…:wink:


( I hate Mondays) #4

Yup, that “someone” is indeed @JDRoberts - I somehow assumed that was public knowledge? :wink:

Outgassing is real, I just don’t happen to care about the risks :wink:


(John C) #5

You can do whatever you wish, of course. Hack away. Maybe you’ll be lucky, maybe not. Whatever.

Your way won’t fly in production. You’ll never ship a certified product that way in a responsible company. But at home? Who cares, right? YMMV.

@JDRoberts is an engineer. His advice is science based, not fake news. That’s it: take the suggestion or not. No “poll” is going to outweigh scientific research. Sorry!

(No offense intended.) :sunglasses:


(Mark) #6

I would take the opinion of one knowledgeable expert over the results of a non-validated group poll. That’s just my opinion though.


#7

Sorry – – I was really tired yesterday, and I didn’t explain things well. My bad. :disappointed_relieved:

Let me give it another shot.

One of the most most challenging things in hardware design is to get yourself in the mindset of assessing risk. The little tiny things that statistically will increase the likelihood of failure above your accepted target.

It’s easy to toss out something that will be a 100% cause of failure. But the challenge is that most of the potential defects are much much more subtle than that.

Let’s take an easy one: smoking and cancer. It’s not true that smoking “causes” cancer. What it does is increase the risk of cancer. (Just as overheating increases the risk of electronic device failure.)

But let’s look at what poll numbers would show.

About 16% of current male smokers will develop lung cancer over 20 years. But a pretty high percentage, usually 50%, won’t know that they have the cancer in the early stages. And cancer typically takes a while to develop.

So if you do a poll and ask people “if you smoke, do you have lung cancer?” You’re going to get over 90% of the people saying no. And if you ask a bunch of college students (almost none of whom will have been smoking for more than 10 years), The number’s going to be even higher. Probably 99% of them will say no.

Because of the way the human brain works, that would cause most of us to jump to the conclusion that smoking is safe. But it isn’t. If you smoke, you are almost 80 times more likely to develop lung cancer then if you don’t. :nauseated_face:

So risk assessment asks us to ignore the way our cave people brains process what we see (99% of people are just fine, thank you) and to look very hard at the actual data to pull out the increased risk.

Smoking is responsible for 85% of lung cancer deaths and about 135,000 people die from smoking – related lung cancer every year. So over 2 million people dead in that 20 year period. That’s a really big number coming from that really small poll result.

The most important part of that mathematically is that the risk increases almost 80 times if you smoke. It’s still a small number out of the total number of people who smoke but it’s a really large number of unnecessary deaths.

As an engineer, I like to see maximum lifespan out of every device. :sunglasses: Thermal management is a big factor there, and weatherproofing almost always changes heat dispersion.

But it’s like smoking and lung cancer. The poll is never going to show the number that matters to risk assessment, which is the avoidable increased risk.

Maybe your sensor will be just fine. Maybe it will last one week less than it should have. Maybe it will die in a month, although that’s not likely. Maybe it will last pretty well, but have 5% more false alerts. Maybe it will use batteries 10% faster. There are a lot of different subtle things that can happen. All I know is that from the physics of it, the likelihood of these subtle issues is significantly increased when you change the heat dispersion on the unit.

Again, check with the manufacturer. If the weatherproofing voids the warranty, there’s a reason for that. It’s just not a reason that’s likely to show up on this kind of poll.

So sorry I didn’t explain things well the first time, that’s my fault. And obviously everybody’s going to make their own choices. When I’ve got an inexpensive sensor running on a mesh network providing me with important data, I like to give it every chance to succeed. And that includes operating it within design specifications. But that’s just me. :sunglasses:


(Mark) #8

And while we’re (sort of) on the topic, don’t forget smoking contributes to a substantial proportion of deaths due to heart disease, stroke and chronic lung disease too. Smoking is seriously bad for you!

Sorry, couldn’t help myself. It’s unusual we ever discuss something on here that I might actually know more about than JD does (I’m a physician). And even then, he’d still probably do a better job of explaining stuff to everyone than i would! :joy:


( I hate Mondays) #9

No offense taken :wink: I use that on a gate outside where gasing is really not an issue. Is it by the book? No way :wink: does it work? Depends on the batteries - I currently have rechargeable CR2s in them. Is my solution production-ready? No way. I am an electronics engineer myself which is probably I am taking risks - I know what could happen :wink:


( I hate Mondays) #10

A recent trend in electronics is a deliberate placement of electrolytic capacitors next to heat sinks. The end result is the heat drying up the electrolytic capacitor, altering its properties which ultimately lead to the failure of the device. I am fairly convinced this is a revenue-driven “calculated risk”. Is it okay to do it? Maybe. Is it moral? No. But they do it anyway. Your TV stops working after exactly one year, right out of warranty? Chances are someone calculated that “risk” properly :wink:


( I hate Mondays) #11

I agree with you on thermal dispersion but not on low powered devices like the battery powered contact sensors. Will wrapping them alter their performance? Likely. But then again, I have an Iris contact sensor in my shed. Most I’ve seen it read was 130F - yeah, that hot. This is today:

What I am trying to say is that the externally generated heat is much higher than the self-generated heat. The way I see it is at most the device may read a slightly higher temperature because of the self-generated heat dispersion disruption, but that is negligible compared to the external heat the device is exposed to.

The shed sensor is not sealed, it is not tampered with in any way.


#12

External heat and internal thermal dispersion are two completely separate issues. It’s why the control panel on an oven might burn out at 200° even though it is expected to regularly endure external temperatures of 450°.

This is the “hotspot” issue that the battery article I quoted in the other thread discussed. It’s not the total amount of heat – – it’s heat in the wrong place, even very small amounts of heat.

A very common oversight is the lack of thermal analysis. In particular, for very low-power battery-operated equipment, it’s easy to think that the power levels are not high enough to worry about thermal management. However, remember that the power density of these handheld systems can actually be quite high…
.
For lower power devices, with only milliwatts of internal dissipation, the end-user may not feel the unit case getting hot. However, if the dissipation in the low-power circuitry is localized to a small “hot spot” inside the unit, there may be concerns associated with device reliability or usability.

There are entire books written, and courses taught, on the engineering aspects of this issue. “Hardware is hard.” Something SmartThings knows all too well. :disappointed_relieved:


( I hate Mondays) #13

The rechargeable battery I use is a 400mAh @ 3V, that is a total potential energy of 1.2Wh. In calories, that is about 1032 calories, which - if expended on a gram of water in a very short amount of time could potentially bring it up by 1032 degrees Celsius. Scary, right? Guess that’s why they say to never short circuit a battery - that will happen - we call it welding :wink: Now, if the battery would last say an hour, that gram of water would get warmer by about 17 degrees Celsius every minute, or by about one degree every 3.5 seconds. It would therefore require a heat dispersion of at least 17.2 calories/minute. Thing is, that battery lasts days, if not weeks. If we assume a day, we’re talking about 0.7 degrees per minute - which is easily dispersed by simple heat radiation, as long as the environment temperature is below the internal temperature. (Sidenote: heat radiation is not a fixed value, the higher the temperature difference between the inside and outside, the more heat is dispersed per time unit) And that is if the heat was concentrated into a single gram of water, which it is not. Outgasing will heat a much larger volume and the device is designed to cool through heat radiation, not free air flow, nor forced air flow. The point is, the theory is correct, energy conserves and the battery’s energy ultimately converts to microwaves (radio signal) and heat. Microwaves ultimately convert into heat as well by means of atomic collisions of photons. Trap too much of that heat in and you’re in for a meltdown. But it’s all about the scale too. There simply isn’t enough energy expended that would cause a device like a contact sensor to overheat - unless something went wrong - like a short circuit - in which case it would fail regardless, as it was not designed to disperse large amounts of heat very fast. And the amount of extra heat that is trapped in by say cling foil is really negligible with respect to the thermal energy available in the environment. I can’t say the same about wrapping your A/V receiver and then playing We Will Rock You at a loud volume. Or tucking your laptop in :wink: now THAT will present some trouble, but we’re talking about instant powers of many Watts that can drive the temperature high very fast. Same theory, same thermodynamic principles, just very different scales.

The question is: can outgasing lead to a short circuit that could potentially bring the temperature up very high and very fast, ultimately causing a fire?


#14

Sure, in some cases, but that wouldn’t be my primary concern. A hotspot is enough to affect the performance of the device. Lost messages, false alerts, lowered battery life… I hate having to replace a sensor and I hate having to replace it early even more. :rage:

Again, for any given model check with the manufacturer. If your intended weatherproofing doesn’t void the warranty, go for it. If it does, there’s probably a reason. But it’s less likely to be about explosions or fires then it is about failure of the device to perform at the expected minimum standard.


(Mike) #15

The data is unanimous: Zero problem with using sealed devices.

I thank all participants.

@JDRoberts, you can see how these little devices don’t follow the old textbook rules. They’re simply too small to have heat or outgas problems. Even in 100+ F degree weather here in Atlanta, I’ve had no problems.

Time to rewrite the textbooks.

Thanks, everyone!


#16

You got six total votes. If you’re going to make any safety decisions based on an unscientific poll with six votes, all I can say is I’m not going to have you working on my house. :wink:


(Mike) #17

First, there is lab testing

After lab testing comes the real-world torture test: Actual field results. N = 6. Pure data.

I don’t know why you can’t see the obvious.

Thanks - Mike


#18

I do see the obvious. :sunglasses: That’s obviously not a field test. That’s anecdotal reports from six people participating in an Internet forum who chose to answer a poll.

That’s not something to base a decision on, although it might be something to cause you to continue to do more research.

Like I said before, talk to the manufacturer, and if sealing the device doesn’t void the warranty, you can make your own decision about it.