Electrolytic capacitors bad news for anything on full power for long-ish time - Page 1
Forum section: electronics / beginners

author: ocset
author_rank: Super Contributor
timestamp: June 16, 2020, 11:06:56 am
content: If you wish, Type “Buy Brushless electronics speed controller” into google.Notice the large number that have their electrolytic capacitors mountedoutsideof the enclosure.The device "use time" is typically only about an hour at a time, yet they go to these “external mounting” extents.This is proof of the general unworthiness of electrolytic capacitors for mounting internally to Power Supply or Drive enclosures, would you agree?Brushless Electronic speed controollerhttps://www.amazon.co.uk/dp/B07D3QG55B/ref=sspa_dk_hqp_detail_aax_0?psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExSEY5WENLMk1VQlNUJmVuY3J5cHRlZElkPUEwMjg3NzgyMklOU1VEUFFaQlFZQSZlbmNyeXB0ZWRBZElkPUEwMzU1NjkzSU5XR1RZNTlZVEZWJndpZGdldE5hbWU9c3BfaHFwX3NoYXJlZCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

author: Ian.M
author_rank: Super Contributor
timestamp: June 16, 2020, 11:28:25 am
content: Nope. They'd have to go to more trouble to put the capacitors inside the enclosure as the values they need aren't available in SMD, and the extra board area to put the caps on the same side as the SMD parts of the rest of the circuit, and the deeper cover that would be needed to cover the caps would both significantly increase costs.Unless the ambient temperature and/or reliability (MTBF) requirements exceed the capabilities of *ANY* electrolytic capacitor, its just a matter of specifying them correctly, positioning them in the enclosure so they aren't heated excessively by other components and buying reputable brands that actually meet their published specs. Of course that costs money, probably at least an order of magnitude more than a far-east 'off brand' part . . . . . .

author: AndyC_772
author_rank: Super Contributor
timestamp: June 16, 2020, 11:28:57 am
content: No.The lifetime of electrolytic capacitors, and the effects of temperature on said lifetime, are well understood and documented by all reputable manufacturers.A design choice made by an engineer on one random throwaway consumer product is not "proof" of anything - except, perhaps, that mounting them in that location, on that product, was cheaper.

author: Ice-Tea
author_rank: Super Contributor
timestamp: June 16, 2020, 11:40:39 am
content: No, I would not agree. See all of the above.

author: ocset
author_rank: Super Contributor
timestamp: June 16, 2020, 12:53:26 pm
content: The enclosure has had to be breached to get the connections of those caps back through to the cct board. Extra expense then needed to keep the IP rating. It surely could be cheaper to lie them flat in an enclosure. Its also an extra pain for the assemblers.As you know, you can get long thin radial caps and lay them flat.Not all devices have such "outside enclosure" placement of large components...if it was cheaper then surely we would see it more often?Most Electrolytic caps have pretty poor lifetimes.....just a couple thousand hours at 105 degC...inside a plastic enclosure for a drive/power supply can easily get to 105degC

author: ocset
author_rank: Super Contributor
timestamp: June 16, 2020, 05:12:50 pm
content: Thanks yes, 12000hrs (500 days) at 105degc is good going at that price.I wonder if the reason they have the caps out of the enclosure is because they are overdriving them, and then need the extra cooling of external placement.Because i bet most of those motor controllers are only in use for "Playtime"...ie, a few hours a week at most.

author: Ice-Tea
author_rank: Super Contributor
timestamp: June 16, 2020, 05:17:53 pm
content: Quote from: treez on June 16, 2020, 12:53:26 pmIn which case the designer should be flogged and the poor elco should not receive any blame.Rules of thumb for elcos (even though I can't imagine you don't know this as you have been doing... something with power electronics for a long time):For every 10C temperature lowers from its full rating, lifetime doubles. So, even a 2k@105C cap will last 64k hours@55C. Or a 10k@105C cap will last 480k hours. With about 10k hours in a year, that's 50 years.Don't blame the elco.

author: bdunham7
author_rank: Super Contributor
timestamp: June 16, 2020, 05:21:28 pm
content: Quote from: treez on June 16, 2020, 12:53:26 pmReally? That seems like an inadequate design practice unless there is some very specific design requirement for tight space and no cooling.

author: ocset
author_rank: Super Contributor
timestamp: June 16, 2020, 05:24:34 pm
content: The Application in mind cannot even have fans, due to their lifetime shortcomings, and the fact they need vents which affect IP rating.

author: bdunham7
author_rank: Super Contributor
timestamp: June 16, 2020, 05:38:22 pm
content: Then the design is being driven by the need to be either light or cheap, or perhaps both. There are plenty of ways to cool things either passively or actively without a vent, and fans can be had with lifetimes of whatever you need--especially in an totally enclosed variant where dust won't be factor.If it absolutely needs to be small and light and run at 105C, you can just buy electrolytic caps that are up to the job.https://www.mouser.com/datasheet/2/88/HHT-1112213.pdf

author: Gyro
author_rank: Super Contributor
timestamp: June 16, 2020, 05:40:26 pm
content: Treez, the stuff you linked in your OP is for RC models. Capacitor life isn't a consideration - they're packaged for minimum size and convenience. Preferably something that can be stuffed in a piece of heatshrink.If you have a serious industrial application, then you're looking at the wrong stuff.

author: ocset
author_rank: Super Contributor
timestamp: June 16, 2020, 06:27:22 pm
content: QuoteThanks, we were looking for fans for use in such environments, and how effective a fan is when it is inside a totally enclosed power supply enclosure, plastic or metal.Our worry would be the fan grease (round the bearings) melting and degrading with temperature, due to being in a hot enclosure.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 17, 2020, 03:26:41 am
content: Quote from: Ice-Tea on June 16, 2020, 05:17:53 pmYes, even in real-life situations, electrolytics commonly lasted 30 years in comms & broadcast electronic equipment in service 24/7/365, & would have probably been good for the extra 20 years, if not for the equipment they are part of being removed from service due to updating.

author: ocset
author_rank: Super Contributor
timestamp: June 17, 2020, 02:25:28 pm
content: Thanks, it would be massively interesting, to hear whether people believe there is in fact any application anywhere which would mandate the NON-use of electrolytic capacitors?

author: Kjelt
author_rank: Super Contributor
timestamp: June 17, 2020, 02:33:42 pm
content: Quote from: treez on June 17, 2020, 02:25:28 pmYes where your product can not be serviced anymore after building it in or the lifetime and/or reliability needed would exceed multiple times the lifetime of electrolytes.So military and space applications do come in mind, even as deep sea sensors.I saw opened expensive broadcast and military electronics to find only tantalum capacitors used in them.Other critical applications such as bridge and tunnel lighting, the hardware is replaced every ten years as preventive measures and the design requirements are 15 years. So that means testing and overdesigning the capacitors, 105C , higher voltage and larger casings then actually needed.

author: AndyC_772
author_rank: Super Contributor
timestamp: June 17, 2020, 02:53:28 pm
content: Quote from: treez on June 17, 2020, 02:25:28 pmI design a lot of automotive products for which an operating ambient temperature well in excess of 100C is completely normal and unavoidable.Given the spikes and surges which can appear on automotive supplies, tantalum caps are potentially a poor choice too. Instead I tend to favour high temperature ceramics.

author: coppice
author_rank: Super Contributor
timestamp: June 17, 2020, 03:28:10 pm
content: Not all electrolytics are created equal. In the 1980s dry aluminium ones drove most other types of electrolytics out of long term equipment, like telecoms infrastructure, for all applications except the big caps in the power supplies. The long term reliability results were excellent.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 17, 2020, 03:29:58 pm
content: Five hundred hours of life for a model airplane controller, particularly a low end one, is effectively infinite. It is something over 2000 typical flights, probably more like 5000. Even top fliers seldom if ever go that many flights without a rapid deconstruction event or two. And that number of flights assumes the temperature is at 105C over the entire flight. A more typical profile would have the cap at some temperature near ambient (though perhaps solar heated to temps up to 40-60C), rising over the flight time to a temperature that might approach 105C. For a flier with a huge investment in batteries you might see a subsequent flight before temps had returned to ambient, but there will still be some relief, extending the predicted life. All of which suggests why I haven't seen a field failure of these capacitors. Not saying it doesn't happen, but it is rare or non-existent at the flying fields I have frequented.These controllers are pushed hard for light weight and high power. My experience is that FET failure is far more frequent than failure of the electrolytic capacitors. I have had that failure personally on a few controllers.

author: ocset
author_rank: Super Contributor
timestamp: June 17, 2020, 03:37:42 pm
content: Thanks, i appreciate all those apps.I believe you would agree this is another one for NO electrolytics...https://www.blumelabs.com/

author: Kjelt
author_rank: Super Contributor
timestamp: June 17, 2020, 04:17:35 pm
content: Quote from: treez on June 17, 2020, 03:37:42 pmIt is stupid to make a life lasting led bulb that is powered on 230VAC.They should sell an external transformer rectifier with 24V or something and do the dc-dc conversion in the bulb.I have Philips Hue light bulbs and small GU10 bulbs , after 20 minutes they are over 60oC , I am really annoyed with that.When does the DC grid finally arrive for these applications

author: nali
author_rank: Frequent Contributor
timestamp: June 17, 2020, 04:18:16 pm
content: Ha - gotta love those dodgy startups with world beating wonder products and marketing heavy websites.Company status - dissolvedWeb contact info - mobile phone number

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 17, 2020, 10:53:56 pm
content: It's hard to build planned obsolescence into solid state components. One way is to use capacitors with short lifespans. Keeps the manufacturers and the technicians happy.

author: sahko123
author_rank: Frequent Contributor
timestamp: June 17, 2020, 11:18:33 pm
content: I think the capacitors are mounted on the outside,A. For better cooling rather than slowly boiling inside if the temps get high.B. Because the required capacitors for one reason or the other weren't available in smaller sizes.

author: ocset
author_rank: Super Contributor
timestamp: June 18, 2020, 01:35:14 pm
content: QuoteThanks, i agree with you, but the concensus here does not.The concensus here is that the caps are on the outside purely because it makes the enclosure able to be smaller.

author: sahko123
author_rank: Frequent Contributor
timestamp: June 18, 2020, 03:51:17 pm
content: Which is what i meant by the capacitors are on the outside because the required ones would be to big for the small enclosure

author: Siwastaja
author_rank: Super Contributor
timestamp: June 18, 2020, 05:11:20 pm
content: Don't overanalyse cheap hobbyist modules. There may not be any particular strong reason for such component placement at all, or it can be anything. It's typical that similar products look similar, i.e., there is a lot of copying around.For example, one design could have had too little DC link capacitance or damping to begin with, then after prototyping they added some extra without respinning the PCB, in this obvious way. Then others just copied this habit.Or, the design might be all SMT, but they have access to low-cost THT elcaps; since the module thickness is limited, the capacitor must be mounted sideways, so this is the obvious way to do it. Especially, if they already need to solder wires directly to the PCB, paralleling the cap with the wires is an obvious construction technique, instead of a separate "just solder the capacitor" step.Obviously, all this have absolutely nothing to do with the lifetime of said capacitors. For such low-hours application, designing the capacitor lifetime not to be the limiting factor is utterly trivial, just don't exceed the ripple current ratings.It's well possible the elcap is just for damping a fairly large amount of low-ESR (ceramic) capacitance and carries only tiny part of the ripple current, not heating up at all. This is how I tend to use elcaps in power electronics, and the lifetime is practically infinite.Proper designs derate the operating temperature spec, ripple current spec, and finally, are not overly sensitive to ESR rise. Typical mid-grade 5000 hours rating can be easily extended to 50000 hours or so. Indeed, if you take a look at randomly selected consumer electronic products from, say, 10 years ago, you will see that most have lasted for a very long time no problem whatsoever, but a few, mostly well-known, suspects fail. The reason for failure is almost always either a very cheap no-name brand, clearly exceeding the specifications, or failure to apply any derating in a product designed for large number of operating hours.

author: Kjelt
author_rank: Super Contributor
timestamp: June 18, 2020, 05:21:08 pm
content: I never ever seen any SMPS from A brands such as Puls, TDK-Lambda, Traco or even a bit lesser brands as Meanwell where the caps are mounted outside the housingHowever when the output power crosses a certain threshold I do see said power supplies being fitted with a fan for active cooling.Now the question, what has the expected less hours lifetime, a fan or an A brand 105 capacitor ?

author: dmills
author_rank: Super Contributor
timestamp: June 19, 2020, 01:03:27 pm
content: The fans have a lifetime Vs temperature curve in the datasheets, just like the caps, at least if you buy proper ones and not PC modder shit.I do NOT get the hate on for electrolytic caps, figure out the operating conditions (Design life, temperature, ripple being the big ones), read datasheets, do sums, kick purchasing in the head until they buy what you told them to, it ain't hard.Sure you can get early failure by screwing the pooch with the sums, or by purchasing shit in the first place, and this is different to any other component how exactly?They are the common fail in consumer products simply because they have a relatively steep price Vs quality curve and actually have fairly well defined reliability even with the cheap stuff, so as a designer if you are told "2 Years at 8 hours a day, 45 degrees C, 1.8A ripple, 400V", you do not need to massively over design to avoid premature failures.

author: tkamiya
author_rank: Super Contributor
timestamp: June 20, 2020, 07:57:02 am
content: I did the same search OP did, but saw only small number of them has external capacitors. I can think of a few reasons.1) They are labeled as input capacitor. There is no telling what will be connected. Used in conjunction with very small SMD components, average user won't be able to replace the cap should it blow.2) Some of them are so small, cap is almost half the size of the board. (meaning including cap, board will be 50% larger) It might be cost saving on PCB production.3) I bet those SMDs are auto populated by pick machine and reflowed on oven. Can't do that with a giant big cap right near by.4) Many appears to use parallel/serial/whatever dozen or so SMD size caps. So it can be done.5) Marketing wise, they can claim "sub-miniature and ultra-light" by excluding the cap from measurement.

author: coppice
author_rank: Super Contributor
timestamp: June 20, 2020, 08:20:06 am
content: Quote from: dmills on June 19, 2020, 01:03:27 pmPeople are just dumb enough to hate the wrong thing. The electrolytics which decay into a festering mess are bad electrolytics, and deserve negative feelings. However, most electrolytics just dry out, which is the fault of the equipment designer, not the capacitor. A huge amount of electronic failures are due to poor thermal management, and electrolytics are probably the most abused parts.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 20, 2020, 08:30:18 am
content: Quote from: coppice on June 20, 2020, 08:20:06 amLikely they are, but they still get disproportionate attention; possibly because people still remember, or haveheardabout the "capacitor plague". Yet in reality, there are other types of typical aging failures as well.I'm not a huge repairer myself, but having repaired a few things nevertheless (it's a good way to learn from the mistakes of others), I have seen an equivalent number of heat-damaged connectors and wire insulation! After all, PVC (and many other plastics) really suffers in long-time operation over about 60-70 degC, while an elcap is still quite OK at that temperature (if ripple current rating isn't exceeded, that is). So I have seen crispy, broken connectors and wires right next to elcaps that are still just fine.Yet this is something absolutelyno oneever talks about. Say, if the ratio of elcap : connector damage is like 3:1, the ratio of discussion thereof is some 100 000 : 1.Many designers (or their bosses, to be fair...) still miss the fact that increasing efficiency tends to be #1 way to solvemanyproblems. Thermal design isn't free!

author: ocset
author_rank: Super Contributor
timestamp: June 20, 2020, 11:09:03 am
content: The western middle men are forcing cost-downs on the Chinese designers which means that inevitably, during a product lifetime, the electrolytics will be down graded to poor, cheap ones that will fail in an unreasonably short space of time……the cheapest will be used that can be gotten away with.Best is to have a checking agency in each country which checks electro’s, connectors, transient protection etc etcThe game of the middle man, is “pay the Chinese designers as little as possible, and charge the western customers as much as possible”. (and hope EEVBloggers don’t do a teardown on you!)Good point on connectors BTW. However, once a connector is specified and on the PCB…its not so easy to swap it out for an el-cheapo production run…but nonetheless, great point, I have a DAB radio on which I had to take the dodgy connector off and solder the 5V straight to the PCB.

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2020, 11:28:50 am
content: Quote from: treez on June 20, 2020, 11:09:03 amI don't know how you managed to transition your topic to cheap DAB radios.Design it correctly and control your manufacturing and sourcing process correctly. If you can't do that effectively, thenyouare the point of failure.Stop linking proper development and production process with random, cheap, off the shelf stuff.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 20, 2020, 12:18:14 pm
content: Yes, while crappy processes are in place, there is a lot of proper design & manufacturing as well.What's best, no one is preventingyouto make the change!If your boss prevents doing proper design, get a new boss. Simple as that.But you categorically dismissing the elcaps does not make you a very capable engineer. There are countless of cases where elcaps are either an absolute must or by far the best solution for the job.If you design for >30 year product lifetime or high temperature (say > 70-80 degC ambient), then elcaps are likely out, but so aremany manyother solutions! This is not obvious at the time of design: from a 80's device, you are now more likely to find a catastrophically failed film capacitor, than a failed electrolytic capacitor! How can you be 100% sure that a modern film cap does not fail like those RIFA caps did?

author: Kjelt
author_rank: Super Contributor
timestamp: June 20, 2020, 01:19:12 pm
content: The problem starts when big money corporations start selling stuff they don't understand for less money than the A brands and people start wondering why the A brands are so expensive and dtop buying them.Then the A brand is forced to lower quality in order to keep on selling their products, hence have to replace their A brand Nichicon, Rubycon, Matsushita elco's with Maxxon, SunSing, Tadingtading brands.This happened and is happening, examples Osram and Philips Lighting vs newcomer Ikea.It is bad for some businesses and also for people that rather have good quality stuff than mediocre stuff that will fail in a few years, but nothing you can do against it.People spent tons of money on certain luxury brands like Louis Vuiton and DG while those products are also made in paycheck slave countries like India and Bangladesh but refuse to pay more for quality normal usage technology products. Only the high tech products are still safe.

author: coppice
author_rank: Super Contributor
timestamp: June 20, 2020, 01:20:44 pm
content: Quote from: treez on June 20, 2020, 11:09:03 amConnectors are one of the easiest things to swap out during a production run. For any high quality connector that achieves even moderate success there will be third party clones of variable quality. Even the original source may produce multiple versions to suitable various pockets, using poor lifetime or poor temperature range plastics, cheaper platings and so on.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 20, 2020, 03:56:15 pm
content: Quote from: blueskull on June 20, 2020, 11:23:45 amIn China, just as in Australia, & other countries, there are companies which spoil a basically good idea, by misguided attempts to "economise", which really reduce costs by only a minimal amount, whilst degrading quality.I worked at an Australian one like that, & also spent a lot of time working on equipment made by a Chinese representative of this category.The Aussie one refused to accept suggestions, which although possibly costing a small amount more upfront, meant big savings in man-hours, plus greatly improved reliability.In the case of the Chinese company, it seemed they "cheaped out" by employing inexperienced EEs for a very short time, then dispensing with their services.Unfortunately, these "rent an EE"s were designing 2kW UHF transmitters, mainly by picking through what they could glean from the Internet.There seemed to be nobody with any real depth of knowledge at this company, either at the Engineering or Technical level, as these transmitters did not work when we received them, & even after we sent them back, two out of five were "no go" when they returned.After trying to get sense out of the company for months, we had to make the things work ourselves, but we still kept finding nice little surprises.Dry joints were common, the RF amplifiers were not tuned to the frequency we used, & the power controller circuitry would sometimes burst into oscillation.With both companies, their crappiness could not be blamed upon the "big, bad, customer!"

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 21, 2020, 08:03:15 pm
content: Chinese manufacturers are forever being made the scapegoats for shoddy quality, but they are simply working under massive constraints often imposed on them by greedy and merciless companies in China and anywhere else in the world. For example if you ask for a capacitor for 1/10 the going price, you may get what you ask for. For Chinese manufacturers, the consequences of failure can sometimes be dire, and the labor force sometimes work in slavery or near-slavery conditions. The quality is understandably below standards in many cases. Other times, it's not.But specify a capacitor with a 100 year lifespan, and a Chinese manufacturer may actually achieve it, and at a competitive price. Quality and cost are not always inversely proportional. Sometimes good engineering can serve both masters; longevity and cost. The myth of having to pay for better quality in every case is being disproved every day. Countless examples exist, in Asia and elsewhere.

author: tkamiya
author_rank: Super Contributor
timestamp: June 22, 2020, 01:28:52 am
content: When customer asks for 1/10 of a price, the answer ought to be, "can't do it for that". But it seems some places goes to reject bin and grab and handful, then sell it for that price.Customer should also know what the fair price of a product is. When something is offered for 1/10 of a price, they must wonder why. Rather than just go ahead and sticking it in for their product and selling it.Ultimate customer (that's us) should also wary of products that are disproportionately inexpensive compared to similar products. But that's what often offered on "SALE!" and they actually SELL!Slave like labor condition in this day and age, that's just inexcusable - but still happens even in modern countries. We kind of demand it by mercilessly price shopping.Blame goes around for everybody involved.

author: coppice
author_rank: Super Contributor
timestamp: June 22, 2020, 09:52:35 am
content: Quote from: tkamiya on June 22, 2020, 01:28:52 amDo you like going hungry?Most engineering starts with an acceptable price. Only the most innovative things and defence projects start from any other point. Engineering is about producing something acceptable to the customer that fits the price constraint. Very often quality can suffer massively and the customer keeps on buying. They might whine and moan about problems with the product, but people always whine and moan about products. What they continue to buy in a competitive landscape is the only real measure of how they feel about what is offered to them. Setting your own standards for quality, rather than listening to the market, can leave you very hungry.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 22, 2020, 02:29:04 pm
content: Quote from: Kjelt on June 20, 2020, 01:19:12 pmIn the long run, people stop buying brands that have unreasonably short lifespans - and the brand gets a bad reputation. IKEA knows what they are doing (long term players) and have minimum requirements that even their cheapest stuff has to meet, they make their money from huge volumes - in other words, I'd be inclined to trust cheap stuff from Ikea more than brand-X cheap stuff from a company with no history and - possibly - no future!

author: tkamiya
author_rank: Super Contributor
timestamp: June 22, 2020, 03:14:45 pm
content: Quote from: coppice on June 22, 2020, 09:52:35 amIf it meant having have to procure parts at TENth of price and make things that are dangerous to users, yes, I'd prefer going hungry. I don't want that on my conscience. Shop owner wouldn't want 80% of what he sells come back either. That will give them cost over-run in customer care, and certainly a bad reputation.You are talking about fairly reasonable business negotiations and demand. I'm talking about extremes.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 22, 2020, 03:23:15 pm
content: Personal anecdote: A Polish friend of mine was familiar with a light bulb factory that had operated under the communist system, and was in the process of being privatized. These incandescent bulbs had a very long lifespan of 5-10 years, and sold for just a few pennies. they were exported very successfully around the world for a year or two. Soon, the factory was purchased by a western multinational light bulb manufacturer, and one of the first changes was to alter the manufacturing process to greatly shorten the lifespan. The price was also greatly increased, and the Polish light bulb factory went out of business shortly after.

author: Kjelt
author_rank: Super Contributor
timestamp: June 22, 2020, 03:29:15 pm
content: Quote from: SilverSolder on June 22, 2020, 02:29:04 pmReread my post I never use brand X with no history. It are the A brands, players in the lighting market for hundred of years that now have no choice than to sacrifice quality and lifetime for low end consumer products to compete with newcomers that sell garbage. Ikea is pretty decent compared to some small chinese factories.I just find that sad as many here, see the cheapo life threatening fake Apple chargers for instance.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 22, 2020, 05:31:38 pm
content: Quote from: Kjelt on June 22, 2020, 03:29:15 pmThere will always be a big market for garbage - and there will always be a smaller one for nicer products. That's how the world works... (I didn't design it, I just live here!)

author: coppice
author_rank: Super Contributor
timestamp: June 22, 2020, 05:37:37 pm
content: Quote from: SilverSolder on June 22, 2020, 05:31:38 pmThis is basically true. The problem is the middle ground of decent quality at affordable prices can get completely hollowed out.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 22, 2020, 07:19:04 pm
content: The most life-threatening accessory I owned was the genuine Apple charger cord that came with my iPad. After a year or two, the outer sheath began to come off, and it began to throw off sparks before it caught fire. A genuine replacement cord (that was barely long enough to be useful) was over $50. I went to the gas station next door and bought a new $3 cord that worked perfectly for years.

author: ocset
author_rank: Super Contributor
timestamp: June 23, 2020, 04:12:09 pm
content: As you know, The equation (5) of page 13 of this…https://www.cde.com/resources/catalogs/AEappGUIDE.pdf..is what governs wet electrolytic capacitor lifetime...Quote(Equation (5))QuoteIts not clear in many wet electrolytic capacitor datasheets, when they say “2000hrs at 105degC”. Do they mean “105degC ambient”, or “105degC case temperature”, or “105degC internal core temperature”?The other problem with wet electrolytics is of course related to the potential for the electrolyte to simply leak out. This exerpt from cornell dubilier shows the problem with short term high temperature transients in wet electrolytics….Quote….so this is the problem, can we be sure that our customer won’t ever temporarily operate the product in such a hot ambient that this temporary overheating of the Electrolytic capacitor occurs?Another point, is, in Equation (5) above…all those temperature parameters depend on knowing what is the internal ambient temperature in the power supply enclosure. Do we really know where the customer is going to use it, and how hot it may become (even for only short intervals).In any case, the internal ambient temperature in a 60W , “fully enclosed plastic case” offline power supply can easily get above 100degC when the external ambient is just 30degC.Then there’s the storage history of the electrolytic capacitor… before being sold, it may have already been stored for years in a hot warehouse, but they pretend they are new capacitors, and fiddle the date code, if there is even a date code.

author: dmills
author_rank: Super Contributor
timestamp: June 24, 2020, 12:19:09 pm
content: You write operating and storage conditions into your spec sheet that you give to the customer, if they choose to play outside your ratings, that's on them, you get to point and laugh.If you spec that your supply can run without derating in say 40 degrees ambient and supply it in a totally sealed plastic box, then it is on you to design the thing so that it does not overheat... Why is this a mystery?I have a list of power vendors that I will never again use for getting this wrong.Storage history you solve by not using the grey market for elcos, FFS. Panasonic/CDW/Chemicon do not in my experience play games like that, and all would be simply fascinated to hear about our CM getting a box of out of date caps from an authorised distribution channel. The rep would I think be beyond narked.Seriously this stuff is basic to running a professional outfit.

author: ocset
author_rank: Super Contributor
timestamp: June 24, 2020, 09:29:07 pm
content: Thanks, ...I mean, if you search digikey for “Aluminium electrolytic capacitor, 450v, 47uF”…..there are virtually none above 105degc.If one operates an El cap above quoted temp, then it can suffer serious damage, significantly affecting its lifetime. I have a Cornell Dubilier doc which states this. The “10 dgec” law doesn’t work when you go above the quoted temp.A 60w offline SMPS, totally enclosed in a plastic enclosure, will easily get above 105degC (internal ambient) at 30degc external ambient.Here is such a power supply....one of many out there..https://www.mouser.co.uk/datasheet/2/260/LPC-60-spec-1109552.pdfThis is why an alternative to El caps is well needed.

author: bdunham7
author_rank: Super Contributor
timestamp: June 24, 2020, 10:14:11 pm
content: Quote from: treez on June 24, 2020, 09:29:07 pmAre you saying the supply you listed will get above 105C (evidence??) or are you saying that such a supplycannot be designed not toexceed 105C?The part you listed has a max ambient of 70C, but is derated above 50C. If you can't design it to stay under 105C, what is the Tj of the semiconductors within? When does the case start to melt? Does the part you listed(an economy LED-driver b/t/w) have el-caps? Does that supply have a significant failure history?Oh, here's a nice film capacitor you could use.https://www.mouser.com/ProductDetail/KEMET/C4AEGBW5500A3LJ?qs=pqRVuuzkf6aQc8hsOFRzpg%3D%3DToo bad it is only rated for 85C !!

author: dmills
author_rank: Super Contributor
timestamp: June 24, 2020, 10:41:16 pm
content: Also, when you are buying Meanwell volumes, you can afford to either qualify parts yourself, or get your preferred vendor to qualify a part for off datasheet use if you really must.It is quite possible to say to a vendor, we would like to use your part XXXXX-YYYY and have volumes of a million a year, but we need you to qualify that part for 125 degrees C, can you guarantee X hours at that temperature if you derate ripple current by 50%? And because you are suggesting a million a year, they might put a reliability engineer on it to run the numbers for you.Not that I think internal temps are getting that high on those stupid little line lumps.

author: ocset
author_rank: Super Contributor
timestamp: June 24, 2020, 11:32:12 pm
content: Thanks, i believe in totally enclosed plastic at 30degc ambient, (with the stated power supply) you'd be looking at 105degc internal ambient....there's just nowhere for the heat to go.Film caps have generally a max temp of 105degc aswell. Though you need to derate voltage in most cases to get this.Eg the MKP1848C64580JY 800V film cap can do 10000 hrs at 105degc and up to 560VDCHowever, if for a short interval, the film cap is taken above 105degc then it will be ok, whereas an El cap getting taken higher than datasheet quoted temperature wont be ok. (as cornell say)Also, at 105degc ambient, the internal temperature of a film capacitor will be close to 105degc, because the esr is so low……eg, the above one is 5 milliohms ESR….whereas the El cap will tend to have a higher internal “hot-spot” temperature due to its higher esr.

author: dmills
author_rank: Super Contributor
timestamp: June 25, 2020, 02:46:07 pm
content: Lets do sums.That 60W Meanwell specifies 85% efficiency (presumably at full load), so ~9W of heat to reject.The derate curve says it can do this at 50 degrees ambient.The case dimensions are a cube 162 * 42 * 30, so 0.026m^2 so the power flux density is ~350W/m^2, as I recall there is a product safety standard that limits the temperature of exposed surfaces, cannot remember the details, but lets assume say 70 degrees outer case temperature is the limit there, should be ballpark?Lets further target an internal temperature of say 100 degrees, then we have 30 degrees across the case wall, so thermal conductance must be at least 11.6W/m^2K Lets see where that gets us?Most plastics come in at somewhere around the 1w/mK, so as long as the wall is thinner then 8cm we will meet that target.In practice the wall will always be thinner then that so the internal temperature will be lower, the actual limit being set by the limit on the outside surface temperature for product safety reasons, at the usual few mm thickness, the internal temperature and case external temperature will be very similar because the thermal resistance of the case is swamped by the crapness of the case as a heatsink.I think that if the outer case is at 70c the internal air temperature is likely only a few degrees higher, so a 105 degree part is likely well within ratings.Someone check my arithmetic.You got to run the numbers, it trumps guessing wrong!

author: Siwastaja
author_rank: Super Contributor
timestamp: June 25, 2020, 02:54:17 pm
content: 0.2 W/mK for generic "plastic" will be closer. 1W/mK could be a special thermally-conductive plastic with fillers, even then it's a good number.Otherwise than that, the problem is always hotspotting in the few heat-generating components, which almost always are a tiny fraction of the total product volume.Your arithmetic assumes the heat is spread internally to the whole volume of the product. It would be nice if it was possible or easy to get even near to that!This is why fan cooling is such a big thing in power supplies after maybe about 200W: many heat-generating components have odd shapes so that mounting heat spreaders or heatsinks is next to impossible: toroid inductors, transformers with the round windings, round electrolytic capacitors... Only the semiconductors are designed to be cooled using metals to transfer heat elsewhere.

author: tooki
author_rank: Super Contributor
timestamp: June 25, 2020, 03:10:21 pm
content: Quote from: Connecteur on June 22, 2020, 07:19:04 pmNo, the genuine Apple cord didn’t cost $50. They cost around $20 for the standard 1m length. High enough that you don’t need to resort to fabricating hyperbolic prices to make your point.

author: ocset
author_rank: Super Contributor
timestamp: June 25, 2020, 04:00:07 pm
content: QuoteThanks very much for this, i think the maths looks all good. However, i am not sure about the assumption of 100degc internal ambient.Also, the "70 degc Max external case temp" i am not sure about.....i mean light bulbs are well above 70degC externally and people can touch them.

author: dmills
author_rank: Super Contributor
timestamp: June 25, 2020, 04:43:49 pm
content: Quote from: Siwastaja on June 25, 2020, 02:54:17 pmGranted, but 0.2 Vs 1.0 just changes the wall thickness to make the assumption hold (to a still stupidly thick), 16mm.The point I was getting at is that the limit is usually surface touch temperatures on the outside of the line lump, not bulk internal temperatures.If you actually open some of those up you often find metal heat spreaders to lower the hot spot temperatures, at least on the sand, by more efficiently coupling the heat to the case. I have even seen the bulk cap with what is effectively a heat spreader!Telecordia GR-63 for non metals in short term contact specs 70c as maximum temperature, 60950-1 (2005) gives up to 95c for plastic or rubber external surfaces of equipment that may be touched, but UL seems to say no more then 45 degrees above ambient, so 85c if assuming a 40 degree upper ambient limit (This is a bit of a case of going down the rabbit hole to identify and I may have misinterpreted something).

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 26, 2020, 02:20:37 pm
content: I hope capacitors don't follow the same fate as ball bearings. Years ago, ball bearings lasted nearly a lifetime. Some unscrupulous manufacturers made them to fail prematurely so that they could sell a lot more of them. It took several decades, but those manufacturers gradually bought out all the long-life bearing manufacturers, and once they had a virtual monopoly they could shorten the lifespan of bearings with impunity. That's why nowadays, bearing replacement is routine and frequent.Old machinery with original ball bearings are the best example of this. They were made to last, and they did.

author: ocset
author_rank: Super Contributor
timestamp: June 26, 2020, 03:24:54 pm
content: QuoteThanks, now that's interesting...the "phoebus cartel" phenomina...again.In cooling fans, the biggest cause of failure is bearing failure....said to be due to use of cheap grease, but as you mention it, yes, its probably to do with the poor bearings themselves.

author: Gyro
author_rank: Super Contributor
timestamp: June 26, 2020, 04:53:04 pm
content: Quote from: treez on June 26, 2020, 03:24:54 pmYou would expect the bearings to be the first thing to fail, they are the only 'wear item' in a fan... Oh wait, there's an Electrolytic capacitor in there!These days, better quality, quieter fans use FDBs.Edit: In the old days bearings tended to have lubrication points, 'sealed for life' bearings have put convenience above ultimate life to some extent (heavily dependent on whether the owner stuck to the specified lubrication intervals, cleanliness and lubricant specifications).

author: Kjelt
author_rank: Super Contributor
timestamp: June 26, 2020, 06:58:38 pm
content: There is something called economic lifetime of a product and TCO.In these days companies don't want to buy a machine that will last 100 years costs 8x as much than a machine they can write off in 5 to 10 years and replace them pre-emptive or even lease machines.It makes no sense.Us hobbieists should do the same when we replace a fan of a benchmultimeter and know we only will use it 4 hours a week on average we don't need an overexpensive fan with bearings that will last decades.On the other hand if you have a company and it is on 16hrs/5days a week you might.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 26, 2020, 07:53:49 pm
content: I saved my money for six months to buy the best video card I could afford for my computer. I was sorely disappointed when it got fried as a result of the cheap cooling fan failing less than a year later. I swore off buying that brand for the rest of my life.It must be the farmer in me, who were notorious for holding grudges for decades against brands that weren't made to last.

author: Kjelt
author_rank: Super Contributor
timestamp: June 26, 2020, 08:17:02 pm
content: Quote from: Connecteur on June 26, 2020, 07:53:49 pmThat is still within warranty you should get a new one.But that fast failing products happens with the best products also.QA people call it infant mortality , look it up under bathtub curve.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 26, 2020, 11:04:11 pm
content: Quote from: Kjelt on June 26, 2020, 08:17:02 pmIt wasn't covered. I got the FU treatment from the seller.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 27, 2020, 12:02:33 am
content: Pretty poor design, that the card didn't throttle itself back when the fan failed.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 27, 2020, 01:16:27 am
content: Quote from: SilverSolder on June 27, 2020, 12:02:33 amSame thing happened to the HP laptop I had when the air vent was covered. It wasn't covered, and I've never bought an HP product since.

author: cliffyk
author_rank: Frequent Contributor
timestamp: June 27, 2020, 02:21:24 am
content: An artifact of the Asian manufacturers cranking out ultra-cheap electronic devices has been a steady degradation in the quality of electrolytic capacitors. They are perhaps the most commonly failing components in contemporary consumer electronics. Cheap test equipment and controls are not immune to this...

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 27, 2020, 02:25:21 am
content: Quote from: cliffyk on June 27, 2020, 02:21:24 amThis has been a team effort. The drive to produce really cheap consumer electronics has created a market for these low quality components. And producers have responded to that market. And designers of further upscale products have been lured by low prices into using them, reducing the market for better quality products. Which further reduces their sales. It is a vicious cycle with blame in many directions.

author: cliffyk
author_rank: Frequent Contributor
timestamp: June 27, 2020, 03:43:46 am
content: Quote from: CatalinaWOW on June 27, 2020, 02:25:21 amOh, absolutely!It's like the "squawk" about Walmart (or pick any evil big box store) "moving in and destroying local businesses..." Uh--NO--it's the local buyers who chose to trade at Walmart instead of their supposedly cherished "local shops" that kill off "mom and pop". If the community ignored Walmart it would go away or have not been built in the first.I am as guilty of this as anyone--it is fundamental human nature: I want to be "fairly" paid as much as I can get for my KSAs (Knowledge, Skills and Abilities), and of course shell out no more than i have to for the labours of others...

author: Kjelt
author_rank: Super Contributor
timestamp: June 27, 2020, 08:51:14 am
content: Quote from: Connecteur on June 27, 2020, 01:16:27 amUser obstructed Air vents are user mistakes and imo rightfully not covered by warranty.A failing fan within the warranty period should.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 27, 2020, 03:05:06 pm
content: Quote from: Kjelt on June 27, 2020, 08:51:14 amPerhaps, but the on-board thermal protection had been deliberately disabled by HP, so that they could sell more new computers. Every other computer I've owned would either throttle back performance or shut down when CPU cooling failed. It resulted in my never buying an HP product again, and my story was told dozens of times to people who asked my advice. I doubt it was a successful strategy for HP either.

author: SilverSolder
author_rank: Super Contributor
timestamp: June 27, 2020, 03:09:36 pm
content: Quote from: Connecteur on June 27, 2020, 03:05:06 pmIt is pathetically poor engineering when a device that can easily be foreseen to overheat has no protection against it.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 27, 2020, 03:29:15 pm
content: Quote from: SilverSolder on June 27, 2020, 03:09:36 pmI'm sure the engineers wanted to keep the thermal overload protection, but the MBAs in the corner office got them to disable it.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 27, 2020, 03:38:31 pm
content: I dated a girl in university who's dad was a top engineer in Detroit. She claimed he invented the original digital dashboard. She said he was forced into retirement because he wanted to build things to last, but his bosses always wanted him to engineer shorter lifespans. Good business I suppose, but so is stealing if you don't get caught.

author: Connecteur
author_rank: Frequent Contributor
timestamp: June 27, 2020, 03:44:23 pm
content: My brother had an Oldsmobile 88, and after a few years the door handle broke. It was very difficult to take the door apart without proper tools, and the broken part was very expensive and impossible to repair. It was a very flimsy piece of plastic, which obviously was made to break after a certain amount of stress being placed on it for a few years. Several other people with the same car had the exact same failure. It's very hard to believe this wasn't a deliberate design to drive customers to the dealerships to make money. Door handles were built reliably a hundred years ago, so something was deliberately changed to make them fail.

author: bdunham7
author_rank: Super Contributor
timestamp: June 27, 2020, 03:57:40 pm
content: Quote from: Connecteur on June 27, 2020, 03:44:23 pmYou can believe what you want but I have never had an engineer tell me that they were told to specifically design something to 'break' after a certain period--it's just too unpredictable. The story I have heard many times is that they were told to incorporate all the latest and greatest features, often to match the competition, but to do so at the lowest possible cost, if not a bit lower than even that. "Doing more and more with less and less".There are instances where things are made to stop functioning on purpose (as opposed to breaking or failing) after some period or amount of use, such as toner cartridges that indicate empty after so many pages regardless of whether they actually are empty, but that's a different story. There are also many instances where things are made to fail in a safe manner when stressed, such as inaccessible thermal fuses, but again, that's another story.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2020, 04:12:12 pm
content: A proper, sustainable, environmentally friendly and also satisfactory to the customer, is a design which is designed to last maybe double the "expected" lifetime, or enough for say 99% of the customers, but no more; and then, all parts start failing approximately at the same time, so that the whole product can be replaced. This minimizes waste.Needless to say, such engineering isverychallenging, but I think Toyota for example has traditionally nailed it, making cars that have room for 200 000km in the maintenance logbook (so this is clearly the "design" lifetime), actually last for 350000-400000km with minor maintenance, then finally starts to rust through everywhere approximately at the same time. (Don't know if that's true anymore. Was true for my 1988 model which I finally got rid a year ago.)Only few can do it.For the rest of us, we need to calculate in larger margins. And be prepared to still have issues of premature failure. The key is not to change too much all the time, but learn from the previous product generations: just fix things that were failing early by looking at warranty repair statistics, or customer feedback if it's a throwaway product.What many laymen and even some engineers consider "good engineering" is often a disaster consisting ofsomeparts massively oversized to last for 1000 years, while some parts require constant maintenance. People who respect products like thatlikemaintenance work; they think it's agoodfeature that "you can repair the product", "it's not a throwaway junk", "look howsturdyit is" (by looking at some overengineered visible part). What they miss is that the product would be much better if it was engineered not torequirerepairing at all! Being able to fix the broken piece of junk makes them happy, but majority of people will just throw it away and buy a new one if it's something say less than $1000-$2000 in value.

author: bdunham7
author_rank: Super Contributor
timestamp: June 27, 2020, 05:02:54 pm
content: For many products, some failures are more acceptable than others. Everyone will have their own view on what is and is not an acceptable sort of failure. Also some components have characteristics that make them impractical to design for intermediate lifespans--it's either forever or you have premature failures. Toyota, something I'm very familiar with, does not actually meet your criteria at all. Even though your old Toyota rusted out and appeared to be all done, I can point you to several things that are 'overengineered' compared to competitors and have virtually a limitless lifespan under normal conditions.I do understand what you are saying and it is one reason that it is not necessarily a good idea to ask your mechanic what the best cars are. My disagreement is over the issue of how large and predictable your desired 'intermediate zone' --between premature failure and 'forever' life at greater expense--actually is. A power supply with a 5-year lifespan is probably designed right at the ragged edge of the component datasheets, if not well beyond--if the components even have datasheets.

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2020, 05:20:24 pm
content: I said it's "very challenging" for a good reason. I presented an ideal, which is obviously unreachable, even by Toyota. Still, it should be the general idea and target. Especially damaging is to have very early failures on key components. Or having 99.9% of the components last for 100 000 hours, yet have one small part define the 10 000 hour lifetime. Large imbalances are the problem.Many parts are, as you say, either "die soon" or "last almost indefinitely". In these cases, you can't do anything else but to choose the latter and be done with it.

author: coppice
author_rank: Super Contributor
timestamp: June 27, 2020, 05:33:46 pm
content: Quote from: Siwastaja on June 27, 2020, 05:20:24 pmA trouble free design needs parts to be engineered to be reliable wherever the car is sold, and that can make their lives almost infinite in some markets. If the design is stripped back there is a danger of it not holding up to extreme stresses. like deep potholes. A car has to sell globally. If you are lucky enough to live in a country where roads are properly maintained, you might well be OK with a significantly stripped back design.

author: bdunham7
author_rank: Super Contributor
timestamp: June 27, 2020, 05:35:38 pm
content: If we're talking about a television, for example, I'm in complete agreement with you. It doesn't matter what breaks, it usually goes in the trash. And nobody wants a 20 year old TV anyway.However, there are some components of some products, like a manual transmission clutch in a Toyota, where a failure is 'acceptable' because we all understand the limitations of clutch technology. If you object that a clutch is a 'wear item', then just use a wheel bearing as the example instead. However, if your door handle broke from anything other than abuse or freezing up, you would consider that substandard. Or at least I would. The expectations are different for different parts.Another example--refrigerators. If any part of the sealed system or compressor failed on my refrigerator, I would be upset and consider the product poorly made even if it lasted 10 years or more. However, if the icemaker jams up and breaks, well after all it's a plastic mechanism working in cold temperatures--so that happens, right?

author: Siwastaja
author_rank: Super Contributor
timestamp: June 27, 2020, 05:42:32 pm
content: Oh, wheel bearings started to sound a bit weird at 380 000 km and were acceptable up to 420 000 km, which was the time most of the body started to finally rust through everywhere. Clutch started to show signs of starting to slip soon at similar time but would have been fine for maybe 50000km more.I have seen cars where wheel bearings are end-of-life after 50000km, while the body lasts for 6-7 times as long.I thing reducing number of "wear items" is great design. Some "wear items" cannot be avoided; I think brake pads and tyres are such examples.I think a refrigerator should last for at least 20 years or so. The reason is, if done properly, this can be achieved with normal level of good engineering. Another reason is, I don't see any reason to "update" to a newer refrigerator (efficiency claims are mostly bullshit).But a smartphone does not need to last 20 years. People want to update for good reasons. Also, they are stressed to external forces and wear.

author: coppice
author_rank: Super Contributor
timestamp: June 27, 2020, 05:50:03 pm
content: Quote from: bdunham7 on June 27, 2020, 05:35:38 pmI think you've skirted around something, but missed the target. If it were technically difficult to make the cooling system in a fridge run continuously without trouble for 10 years, we would have to get used to that, and accept a shorter life. However, decades of mass manufacture have taught us to expect at least 10 years, and anything less is unacceptable. That is our baseline for solid practical reasons. On the other hand, its easy to make the icemaker strong enough to work well for 10 years, and we know that. We can see how flimsy it is, and how the additional cost of making it stronger wouldn't be huge. However, for some reason people seem more and more accepting of things like fridges gradually losing bits, like ice makers, and shelf supports, and unreasonably thin glass shelves, and door handles (the door handle of our 2 year old Samsung fridge has fallen apart just this week. Its still under warranty, we should be OK). People even blame themselves for failures. "I suppose we shouldn't have put so much on those thin glass shelves". Damnit, those shelves are supposed to be strong enough for you not to worry, or the product fails the fitness for purpose test.People need to less tolerant.

author: bdunham7
author_rank: Super Contributor
timestamp: June 27, 2020, 06:04:03 pm
content: Quote from: coppice on June 27, 2020, 05:50:03 pmThat's more or less my exact point. I didn't say it explicitly, but my expectation about that system is based on experience and a general knowledge of the basic systems.QuoteI disagree about icemakers (although mine is 25 years old and works fine) simply because they are exposed, mechanical systems. I understand they can break and I don't think you can easily design that possibility out of them. And, of course, they are less important. As for the rest of your stuff breaking, see my comments elsewhere about 'doing more and more with less and less'. Not only should people be less tolerant, they should be more willing to fork out a premium for 'invisible' quality like stronger, more robust parts rather than an infinite variety of doodads with marginal utility.

author: coppice
author_rank: Super Contributor
timestamp: June 27, 2020, 06:13:42 pm
content: Quote from: bdunham7 on June 27, 2020, 06:04:03 pmThe customer no longer has a choice. When we bought our current fridge 2 years ago I was very concerned about how fragile things like the shelves seemed in every fridge I looked at. It didn't matter if it was a low end or a high end model. It didn't matter which brand I looked at. I couldn't find anything with the robust feel of even a cheap fridge from the 80s or earlier.

author: Zero999
author_rank: Super Contributor
timestamp: June 27, 2020, 07:14:19 pm
content: Quote from: treez on June 24, 2020, 09:29:07 pmThere are loads rated to 105oC and I found this one rated to 125oC on the first page of results.https://www.digikey.co.uk/product-detail/en/tdk-electronics-inc/B43866C5476M/495-6100-ND/3500156This one is 100µF, 250V 130oC. Use two in series, with suitable voltage sharing resistors.https://www.digikey.co.uk/products/en/capacitors/aluminum-electrolytic-capacitors/58?k=&pkeyword=&sv=0&pv252=156406&sf=1&FV=-8%7C58%2Cmu100%C2%B5F%7C2049%2Cmu250V%7C2079%2Cmu280V%7C2079%2Cmu300V%7C2079%2Cmu315V%7C2079%2Cmu330V%7C2079%2Cmu350V%7C2079&quantity=&ColumnSort=0&page=1&pageSize=500

author: SilverSolder
author_rank: Super Contributor
timestamp: June 27, 2020, 08:29:43 pm
content: Quote from: Siwastaja on June 27, 2020, 04:12:12 pmI worked in the automotive industry for many years, for my sins. Including in QA. Basically, a car (and every component that goes into it) is rated and tested for 100,000 miles and 10 years, in specific "worst case" environmental conditions. This is what all the component makers have to contractually fulfill - and woe betide a supplier that doesn't meet the quality criteria (which includes corrosion resistance). (GM would have had words (and money) from the supplier of the Oldsmobile door handles mentioned above, if the failure rate was above contracted levels.)So your observation is 100% correct - cars ARE designed to have every component fail at the same time - but in the worst case conditions of heavy use and corrosive environment! This requirement means that most cars can last 200K miles or even more, if taken care of (kept clean, oil changed, etc.).It also means that if you buy a used car with more than 100K miles or 10 years on it, you are buying a vehicle that is past its designed end of life... not that you would know, based on used car prices...

author: TimFox
author_rank: Super Contributor
timestamp: June 27, 2020, 08:45:43 pm
content: With respect to all subsystems failing simultaneously, the classic account is an 1858 poem by Oliver Wendell Holmes, Sr (1809 -1894), American physician and the father of Oliver Wendell Holmes, Jr who served on the US Supreme Court.http://holyjoe.org/poetry/holmes1.htmThe "One Hoss Shay" is a carriage built by a deacon who knew that a machine failed at its weakest point, and therefore avoided having any weak points in the construction. Economists use the term to denote a depreciation calculation where the depreciated asset has no scrap value.