Beware of Chongx capacitors - Page 1
Forum section: electronics / projects

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: May 11, 2020, 08:46:21 pm
content: I recently got a capacitor kit with "Chongx" (Thongx?) electrolytic capacitors. All pieces for multiple values are failing at the rated voltage!

author: exe
author_rank: Unknown
timestamp: May 11, 2020, 09:25:04 pm
content: Is it possible the + and - terminals are "swapped"?

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: May 11, 2020, 10:26:37 pm
content: No, in the opposite direction the current starts to shoot up at an even lower voltage. They maybe mislabeled, at 5V seem to be OK.

author: wraper
author_rank: Unknown
timestamp: May 11, 2020, 10:42:58 pm
content: I've bought some "LOW ESR" caps at local shop a few years ago. Turned out to be ChongX with golden marking and suspiciously small size. ESR was crap. Checked under rated voltage and leakage current was a few mA. Which dropped a lot with a bit reduced voltage. So rated voltage was totally fake.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 11, 2020, 11:00:01 pm
content: Quote from: maxwell3e10 on May 11, 2020, 08:46:21 pmDo they get hot when you test them like this?0.24 x 15 = 3.6WThey should get hot really fast,Jay_Diddy_B

author: John B
author_rank: Frequent Contributor
timestamp: May 11, 2020, 11:09:05 pm
content: There's also Chengx and Changx, though I don't know what the difference is. Ie whether they are a related company or knock-offs of each other. I have no issues with a collection of Chengx ones, they are 63V and I took a few of them above 63V as a test without problems.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: May 11, 2020, 11:46:25 pm
content: Quote from: Jay_Diddy_B on May 11, 2020, 11:00:01 pmYes, this is just for a few seconds, you can see it's already current limited and voltage is starting to drop. Someone on Youtube has a video blowing them up like this.

author: amyk
author_rank: Super Contributor
timestamp: May 12, 2020, 01:42:37 am
content: Maybe they need to be reformed, since they have sat for a while without voltage.

author: Bud
author_rank: Super Contributor
timestamp: May 12, 2020, 03:11:37 am
content: Quote from: maxwell3e10 on May 11, 2020, 08:46:21 pmFrankly, I would not touch anything with such name with a 10 foot pole in the first place.

author: mawyatt
author_rank: Super Contributor
timestamp: May 12, 2020, 02:17:34 pm
content: One thing that might help would be to look at the relative size of similar capacitors, this might give an indication if these are mislabeled. Capacitors with the same capacitance and voltage rating would have similar volumes.From your images, these look small for 470uF at 16V.Anyway, good you found this before using themBest,

author: wraper
author_rank: Unknown
timestamp: May 12, 2020, 02:52:24 pm
content: Quote from: blueskull on May 12, 2020, 02:30:44 pmWasn't Chang (Changzhou Huawei Electronics Co. Ltd)http://www.huaweiec.cn/the original one? They were available more than 2 decades ago for sure and company supposedly exists since 1987. And then the rest appeared later AFAIK, all having virtually the same logo. Like Chong, Cheng, ChangX, ChengX, ChongX...

author: jaycee
author_rank: Regular Contributor
timestamp: May 13, 2020, 11:27:40 pm
content: ChongX.. like most chinese electrolytics.. only useful for firing down the garden when bored

author: Shock
author_rank: Super Contributor
timestamp: May 14, 2020, 06:27:48 am
content: Stick to the quality brands rather than Chinese rubbish. The good manufacturers will sell caps in different series and provide datasheets.https://www.tomshardware.com/reviews/power-supplies-101,4193-5.html

author: wraper
author_rank: Unknown
timestamp: May 14, 2020, 10:12:25 am
content: Quote from: blueskull on May 14, 2020, 06:49:25 amThat's not true. Teapo/Yageo are very widespread. Elite is not uncommon too and is quite often used in Dell equipment. As of Chang, I found them even in some $40k equipment, LOL.

author: Shock
author_rank: Super Contributor
timestamp: May 14, 2020, 11:44:22 am
content: I avoid buying Chinese branded and made in China products where I can. I'll stick to Japanese capacitor brands and avoid the Chinese fakes, clones, partial or nonexistent datasheets, slow delivery times and lack of warranty. I'd also much rather support local distributors here where they gather quality brands from around the world and deliver same or next day.

author: Psi
author_rank: Super Contributor
timestamp: May 14, 2020, 12:26:36 pm
content: Why not replace with some of these quality caps

author: madires
author_rank: Super Contributor
timestamp: May 14, 2020, 01:31:06 pm
content: Quote from: wraper on May 14, 2020, 10:12:25 amI can confirm that Yageo is commonly seen in products, I even have some in my hobbyist stock. Also no problems with running them 24x7 for years, e.g. in DC/DC converters.

author: Shock
author_rank: Super Contributor
timestamp: May 14, 2020, 04:58:27 pm
content: Quote from: Shock on May 14, 2020, 11:44:22 amSo you won't sell me your parts because I probably won't buy them, makes sense. The only reason I don't buy much from China is I can get better elsewhere. Xiaomi Hisense and Huawei type products don't appeal to me at all. You still have the whole rest of Australia that might be interested in something, no need to end trade talks preemptively. Lol.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: May 14, 2020, 07:13:51 pm
content: Quote from: amyk on May 12, 2020, 01:42:37 amReforming them actually worked! By limiting the current to a few mA at first and then running them for a couple of days I can get the leakage current to about 1 uA at rated voltage. But the capacitance values dropped to 60% of the nominal value! I don't think it's really "reforming", but forming them in the first place. From what I read a capacitor usually undergoes voltage soak at the end of manufacture. Not sure if they are skipping on that step to get higher capacitance or it was just a bad batch.

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 14, 2020, 07:23:35 pm
content: Quote from: mawyatt on May 12, 2020, 02:17:34 pm+1, it looks like 47uF 16V size, it must be 470 uF 6,3V max.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: May 14, 2020, 07:56:31 pm
content: Yes, it's 6.3x11 mm size and for this size the largest capacitor I see listed at 16V is 330 uF. And guess what, after reforming 470uF turned into 300 uF. So there is no free lunch.

author: Zero999
author_rank: Super Contributor
timestamp: May 14, 2020, 10:05:28 pm
content: Quote from: blueskull on May 14, 2020, 06:49:25 amYou can't blame westerners for not trusting Chinese capacitors. No doubt there are plenty of decent Chinese capacitor manufactures and indeed most of them will be genuine. The problems are there are so many brands, with strange sounding names no one in the west has heard of and there was the capacitor plague scandal of the early 2000s, so the high index of suspicion is perfectly understandable.If one is prototyping, building small volumes, or the product has a high mark-up value, there's no need to use unfamiliar brands. Capacitors are cheap and there's no point in trying to skimp on them. I'd rather stick with capacitor brands I've used before without any problems, than some unknown brand. Perhaps if it was a high volume consumer product, it would make sense, but I'd subject large samples of different batches for intensive testing first.

author: jaycee
author_rank: Regular Contributor
timestamp: May 14, 2020, 10:17:45 pm
content: All I know is what I see when I repair equipment.. CapXon, Teapo, ChengX, G-Luxon, all sorts of cheap Chinese crap, usually leaked and bulging all over the place hence why the thing has stopped working. I can count on one hand the number of times I have seen a Japanese or other quality manufacturer's capacitor exploded, and that has usually been from a failure elsewhere in the circuit which has caused overload.Personally, I tend to use Panasonic.

author: Shock
author_rank: Super Contributor
timestamp: May 15, 2020, 04:35:16 am
content: Quote from: blueskull on May 15, 2020, 02:26:48 amIt seems we both dislike cheap Chinese products and fakes.Blueskull, you do not yet realize your importance. You have only begun to discover your power. Join me, and I will complete your training. With our combined strength, we can end this destructive conflict and bring order to Shenzhen.

author: uer166
author_rank: Super Contributor
timestamp: May 15, 2020, 06:23:51 am
content: @blueskull, this has always intrigued me, I have absolutely no problem using Chinese made components/capacitors, but was always lost on how/where to find the right components. How do you figure that "series X" from "manufacturer Y" has repeatable performance at a good price, vs. obliviously fake ratings like the OP's case. Obviously using Panasonic from Digikey guarantees success 99.99% of the time, but as you said, something 10X cheaper at similar performance is indeed available.I feel like this is as much an education issue as it is pre-concieved notions and biases. Say I want a 47uF, 100V, 0.5A 100kHz ripple electrolytic. How do I go about finding a (reputable) Chinese brand with a good track record. And further, how would I go about getting a reel of them to an assembler?From my experience, many components in US automotive products come from unknown-to-the-public Chinese suppliers, and they perform great at a competitive price. Considering automotive is a low margin business, this is essential. Not only that, but the suppliers are more willing to cater to custom requirements than big-name well known brands.

author: uer166
author_rank: Super Contributor
timestamp: May 15, 2020, 09:39:18 am
content: Quote from: blueskull on May 15, 2020, 06:40:48 amWhy is insider information necessary? Isn't it in the manufacturers self-interest to sell as much product as possible? If I was making caps I would provide as much information to the world as possible, datasheets, test reports, reliability info etc etc, to make sure people can design those into their products with confidence. I guess the language barrier complicates things..

author: Ice-Tea
author_rank: Super Contributor
timestamp: May 15, 2020, 10:07:52 am
content: Quote from: uer166 on May 15, 2020, 09:39:18 amYou seem to assume this information is always available. It's not. You're used to manufacturers characterizing their products with tolerances, temperature influence, corner cases etc etc. Chinese manufacters will make- a product with no information beyond "16V, 470uF" because they made one, it didn't blow up when and so they are selling it- a copy of a product, and so they will copy all the specificactions of the original product without verificationSo if you want to know if it is *actually* any good, talking to someone who knows the ins and outs certainly helps, talking to an existing customer also works as they may know more about the product than the manufacturer does.Off course, you can also get a very well spec'd quality product from a chinese vendor. Just depends on how much you want to pay.

author: exe
author_rank: Unknown
timestamp: May 15, 2020, 12:49:00 pm
content: I'm open for capacitor suggestions. I mostly use Panasonic, but they are expensive. I also have two caps from Wurth, and a few from Kemet that I got on discount. And one tantalum-polymer from AVX. I can't really explain why I chose Panasonic. I didn't do any endurance tests. It's probably when I see an unknown brand and Panasonic I choose Panasonic.I also bought some Nichicon because they are wide spread and used in expensive gear (I know Dave likes to rant about them, I don't believe him because he doesn't provide any data).

author: madires
author_rank: Super Contributor
timestamp: May 15, 2020, 02:25:55 pm
content: You can add also Jamicon and Roederstein (Vishay) to the list.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 15, 2020, 03:51:58 pm
content: I have also seen several Lelon, Teapo, Chang, Jamicon and others on the wild in several products, and their quality varies with the variant chosen by the designer. Case in point: the photo below shows 10yr+ Jamicons on a CFL reactor still with great ESR.Although I have seen much more Chinese and Taiwanese brands destroyed/bulged/leaked when compared to the Japanese ones, these were usually on low-end or cheaper products, which is somewhat expected.False ratings are a shame regardless of brand, though - and nowadays I have seen not only the chinese lowest tier brands (knockoffs of the ones above) with terrible ratings, but also a lot of fake Japanese branded copycats as well. It becomes harder and harder to discern them, and the only way to have better certainty is through the supply chain - something harder to do if you are purchasing from a peripheral country due to taxes and delays.

author: amyk
author_rank: Super Contributor
timestamp: May 16, 2020, 03:33:51 am
content: Quote from: blueskull on May 15, 2020, 02:26:48 amIf you want to go down the rabbit hole of standard Chinese capacitor types...https://www.eevblog.com/forum/chat/electrolytic-caps-and-their-cd-type-(cd263-cd296-etc-)-what-does-it-mean/

author: Zero999
author_rank: Super Contributor
timestamp: May 16, 2020, 10:18:39 am
content: Quote from: jaycee on May 14, 2020, 10:17:45 pmConsumer gear is often build down to a price, so it's not surprising there is more of a problem with exploding capacitors.I just go for Kemet, Rubycon, Chemicon, Wurth, Nichicon etc.

author: OwO
author_rank: Super Contributor
timestamp: May 16, 2020, 10:45:20 am
content: For prototypes I... alternate between rubycon/nichicon and chengx capacitors, all from LCSC so I can be sure they are the real deal. Mainly so I will be able to do comparisons if they start failing years later. The issue with reliability is you just don't know until many years later, and by then manufacturers probably have already changed formulas.But the rule of thumb here is to mix in some substandard parts when mass-prototyping, so I can get to see more failure modes and potential issues with the design.

author: wraper
author_rank: Unknown
timestamp: May 16, 2020, 11:45:04 am
content: Quote from: Zero999 on May 16, 2020, 10:18:39 amSurprise for you, recently Yageo acquired Kemet which adds up to Teapo and Jamicon they already owned.

author: Ice-Tea
author_rank: Super Contributor
timestamp: May 16, 2020, 11:54:43 am
content: Quote from: OwO on May 16, 2020, 10:45:20 amThat's what HALT is for..

author: Bassman59
author_rank: Super Contributor
timestamp: May 16, 2020, 04:50:21 pm
content: Quote from: blueskull on May 15, 2020, 06:40:48 amAnd this is why non-Chinese designers and manufacturers are leery of Chinese parts. If we don’t have the secret decoder ring of inside knowledge and connections, we can’t play this game. And since most aren’t as massive as Dell or Apple, we don’t have the resources to invest in the grifty middleman. So we buy name-brand parts from vendors/distributors we trust. And this is especially true when the products aren’t mass-produced cheap consumer junk that gets only one production and then it’s done.Maybe if the Chinese vendors didn’t act like used car salesmen, we wouldn’t hold these opinions of their products and business practices.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 16, 2020, 10:07:25 pm
content: Quote from: blueskull on May 16, 2020, 05:49:33 pmExactly. This is still the norm in most manufacturers these days (case in point: RPi's main processor).Only somewhat recently (maybe two or three years) that some manufacturers started having their own online store, but prior to that you always had to talk to a broker or distributor for pretty much any MOQ (unless you were a huge multinational).Similar thing used to be true for direct technical support, although that changed a lot longer ago with the support forums. When I started in this industry, to talk to a manufacturer you had to be tied to a large company or key university.

author: M4trix
author_rank: Frequent Contributor
timestamp: May 17, 2020, 12:57:58 am
content: What about this manufacturer ? I have a bunch of KM series caps and I'm not sure about their quality. Anyone has some experience with this brand ?http://www.jiaweicheng.com/enhttp://www.jiaweicheng.com/en/product/56822182.html

author: wraper
author_rank: Unknown
timestamp: May 17, 2020, 01:33:21 am
content: Quote from: M4trix on May 17, 2020, 12:57:58 amMeh, pretty crappy. At least their LOW ESR caps. You likely will be fine with general purpose series not under stress.

author: M4trix
author_rank: Frequent Contributor
timestamp: May 17, 2020, 01:39:10 am
content: So, in other words... not recommended to use in life supporting equipment.

author: VK3DRB
author_rank: Super Contributor
timestamp: September 29, 2021, 12:50:32 am
content: Really, REALLY bad capacitors...

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 29, 2021, 12:59:01 am
content: Quote from: Bud on May 12, 2020, 03:11:37 amHere you gohttps://www.aliexpress.com/item/4001200776394.html?spm=a2g0o.productlist.0.0.13d83017fJTvFN&algo_pvid=a77a103a-89dc-463a-8df3-68f4407226f0&algo_exp_id=a77a103a-89dc-463a-8df3-68f4407226f0-0&pdp_ext_f=%7B%22sku_id%22%3A%2210000015281838849%22%7D

author: Bud
author_rank: Super Contributor
timestamp: September 29, 2021, 03:27:57 am
content: Quote from: VK3DRB on September 29, 2021, 12:50:32 amThou shalt downscale all Chinese tech specs by a factor of 2.

author: Psi
author_rank: Super Contributor
timestamp: September 29, 2021, 08:51:40 am
content: yeah, you've really got to be careful getting some types of parts from aliexpress.A lot of the sellers their literally do not know what they are selling. You often see sellers with listings of everything from baby clothes to capacitors. They got a box of them from somewhere for cheap and are listed them on their store. It's pretty likely they got them cheap because they are the factory rejects for one reason for another.Before I buy any electronic parts from an aliexpress seller I look at their other listings and make sure they specialize in that type of item. Seeing totally random products is a big red flag.

author: rsjsouza
author_rank: Super Contributor
timestamp: September 29, 2021, 11:04:51 am
content: The video is indeed entertaining, but unfortunately not rigorous with the details regarding tolerance and ESR.These are most probably manufacturing rejects. I have seen ChongX capacitors in ten years old equipment still in one piece.I have also seen one case where they blowed up at 66% of their rated voltage, but it was from a kit that a dude in China built and he might have sourced them from the same "reject special".Overall, the message is still useful. Thanks for sharing.

author: wraper
author_rank: Unknown
timestamp: September 29, 2021, 11:53:44 am
content: Quote from: rsjsouza on September 29, 2021, 11:04:51 amI don't think they are rejects. Claims about rejects from original factory are a myth in 99.9% of cases. Outright counterfeits, ChongX with fake voltage ratings I've seen were unusually small for their capacitance and voltage ratings.QuoteDepends on voltage they were used at. Even those fakes will work if voltage is low enough.

author: rsjsouza
author_rank: Super Contributor
timestamp: September 29, 2021, 12:50:45 pm
content: Quote from: wraper on September 29, 2021, 11:53:44 amI don't know about the percentage, but I know of manufacturing rejects and test run units that were sold by the reels on eBay and other marketplace venues (through specific markings on the parts' packaging). It might be an easy excuse for a lot of sellers, but it can surely happen.Quote from: wraper on September 29, 2021, 11:53:44 amPrecisely. That is why these can still be useful in the regular 3.3V circuits. What I expect is they might last for 200, 500 hours max.

author: wraper
author_rank: Unknown
timestamp: September 29, 2021, 01:01:35 pm
content: Quote from: rsjsouza on September 29, 2021, 12:50:45 pmI did not say it does not happen, just that it's very rare compared to counterfeits or recycled crap sold as new.

author: Shock
author_rank: Super Contributor
timestamp: September 29, 2021, 01:40:52 pm
content: Quote from: wraper on September 29, 2021, 11:53:44 amWhat would be to us unprofitable and a huge risk to our reputation and employment - is like hitting the jackpot for the guy who empties waste bins in China.

author: Haenk
author_rank: Super Contributor
timestamp: September 30, 2021, 08:13:39 am
content: A good electrolytic cap requires some serious chemical engineering, and all of that is certainly patented.I doubt the common chinese part is even close to the quality of "major manufacturers". Certainly a dollar saved at the wrong place when using the cheap stuff. Don't do it.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 30, 2021, 09:10:26 am
content: Electrolytic caps are around for a long time already, especially the older classic ones. Only the low ESR types are relatively new. Patents have a limited effective span, and after this one is free to use at least the technology that is more than 20 years old. I don't think there are that many secretes anymore about the chemistry of the caps like made in the 1980s.A common problem with cheap parts is a lack of quality control. They sometimes seem to produce parts without ever testing or knowing how to use them. Some of the parts are Ok for a great price and sometimes there are not enoughto go around for the stupid mistakes they have in the products. I would not be surprized to find extension cord with 2 female ends - though the male end may be cheaper.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 01, 2021, 07:26:21 pm
content: Quote from: Bud on September 29, 2021, 03:27:57 amIt's more of an XOR thing. I bought a off-line generic Chinese PSU rated at 5V 2A. You might think it means 5 volts at 2 amps, but it really means 5 volts or 2 amps, but not both.

author: Spar59
author_rank: Contributor
timestamp: January 02, 2024, 02:59:09 pm
content: I know this is an old thread but my search engine linked to it when I seached for "Chongx" in 2024.I have two 24V to 240V inverters, identical in design, one started showing a bit of voltage drift.I opened it up and found a bulging "Chongx" 3300uF 35V 105°C capacitor - obviously not good and I will replace it and its 3 partners (all connected in parallel to give 132,000uF), with Panasonic low ESR high ripple ones from a commercial distributor to guarantee originals rather than fakes. The failed capacitor measured just a few nF, the other 3 measured ok at around 3300uF.I therefore opened up the other inverter and also found one of the "Chongx" capacitors bulged, I have not bothered to test them as all 4 will be pre-emptively replaced. However this inverter had been at 66% load prior to being opened up and the capacitors were rather hot - not at 105° but at a temperature that would not be good for their longevity, the heating would be as a result of ripple current and their proximity (<1cm) from the DC-DC converter transformers which run hot - the inverter being pure sine with a DC-DC converter followed by a PWM bridge chopper.Out of curiosity I unwrapped the failed capacitor and one of its partners, both had uneven film wraps that did not fully cover the cans. Underneath I found damage to the cans, dents and ridges, as if they had been grasped with pliers, perhaps they were pulled from equipment and were then re-wrapped. However you need to bear in mind these were not sold on to amateurs via an e-commerce web site, which has become awash with fake parts, but sold to a manufacturer to incorporate them in his equipment, in this case a 1500W/3000W inverter badged "Escatee".

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 02, 2024, 03:05:37 pm
content: Quote from: Spar59 on January 02, 2024, 02:59:09 pmOutput AC voltage drift may be caused by ultra-cheap AC voltage divider feedback resistors. I had similar problem with one of my inverters (12VDC-220VAC). I replaced original factory ones with just regular good ones from one of reputable brands and voltage drift decreased several times (from 2-3 VAC drift to about 0.5 VAC drift).

author: Spar59
author_rank: Contributor
timestamp: January 02, 2024, 06:34:22 pm
content: ThanksThese inverters run as part of a solar and energy transfer system, at this time of year more transfer than solar, where the system batteries are charged overnight on cheaper rate electricity and discharged during the day. One inverter can manage the load but using two allows cooler running and allows for failures.I don't want to take this thread off-topic i.e. cheap capacitors but here is the full story:The voltage drift is temperature dependent and affects both inverters, I think due to gain variations in the feedback opto coupler from the circuit monitoring the main HV DC bus that supplies the output choppers back to the low voltage side of the DC-DC boost converter, it is repeatable depending on how hot the unit is and only results in about 4% drift, which is better than the mains supply tolerance of 240V +/-6% so although it may be considered poor design wasn't a show-stopper for a cheap inverter.There was virtually imperceptible load-dependent drift, other than a slow shift resulting from increased temperature as the unit would get hotter at higher load, until the cooling fans cut in and cool it.It is interesting to note that although these are 1500/3000W inverters i.e. 1500W continuous, in the sales literature, the user manual says to shut it down for 15 minutes if the cooling fans run - there is no way it can get anywhere near 1500W without its fans! Even at 50% load they run in warm weather, but they do cool the unit effectively - I think they are trying to cover themselves for bearing failures on cheap fans.The faults:I have an external voltage monitoring system set to 240V +/-6% this operated and took number 2 inverter off-line, transferring its load to mains, and shutting down its DC supply.I then transferred all load to the second inverter which was now running at around 80% of rating.I found the bulged capacitor in inverter 2 but did no further investigation as I was now awaiting a replacement and ordered sufficient to replace all four in the failed inverter plus pre-emptively replace those in the other unit.The following day inverter 1 failed with a sudden voltage drop of over 8% triggering the voltage monitoring equipment which took the inverter off-line, transferring all load to mains and shutting down its DC supply. I powered it back up and found its output voltage was now very load dependent, at around 25% rating and it ran as normal, at the previous load level the output voltage was around 9% low.I investigated and discovered a bulged capacitor in its DC-DC converter section, deja vu. This could have been triggered by the higher than normal ripple current due to the additional load normally fed from inverter 2 that it was now also carrying, but the load was still well below its continuous rating and hence well below the maximum ripple current this unit would put through the capacitors.I removed the capacitor and found it to be only a few tens of nF, not the 3,300uF it should be, obviously as it was in parallel with 3 other identical capacitors the effect was a reduction from 13,200uF to 9,900uF and hence presumably resulted in operation in a non-optimal fashion rather than a complete failure to operate, reverse engineering the circuit due to large components, particularly the transformers, covering the PCB tracks isn't easy but if a replacement capacitor solves the issue it would be academic only.Now are those 220uF 500V, low ESR, high ripple smoothing capacitors on the HV DC bus really genuine grade 1 Nichicon or not??? I suppose time will tell, I hope they are ok as replacements are not only difficult to source but very expensive.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 02, 2024, 10:49:51 pm
content: Quote from: Spar59 on January 02, 2024, 06:34:22 pmInterestingly I have a similar story with my inverter but without bulged caps.I had done some experiments with my 12/220 inverter too. I had PCB only (w/o a case) accidentally, so needed to make a case for PCB, so I put the PCB into the larger case. I found that with a good large case and large heatsinks the hottest parts are those input bypassing electrolyte caps. The large case causes slow airflow. Transformers became hot too but not as fast. The rated power of my inverter is 1100 W but input electrolytes became too hot at about 600-700 W of output load, so about 60-70%. Interestingly they are not equally hot, but the first one closer to the 12VDC input is the hottest while another three ones are not as much. Since my inverter is 12 VDC rated I could use 16 VDC rated caps and I replaced factory low-ESR electrolytes with 1500 uF 16V polymer ones (which are easy to get comparable to 35V rated) and still the first one is boiling. It definitely needs an airflow passing right through it (like it was designed to be with an original tight factory case). Since I don't need so much power from it (I need 100-200W) I left it as is.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 02, 2024, 10:56:21 pm
content: Quote from: Spar59 on January 02, 2024, 06:34:22 pmThose HV electrolyte caps I've seen are typically fine and don't cause trouble themselves. They don't bulge fast until something causes it, like a feedback fault or power switch fault, etc.

author: Spar59
author_rank: Contributor
timestamp: January 03, 2024, 12:28:49 am
content: A quick examination of the PCB layout does indeed suggest that they are in fact wired directly across the incoming 24DC supply (after the fuses), hence just filter caps, but obviously subjected to huge ripple currents, in which case the effect of losing just one and it seriously affecting voltage regulation is dubious - I may have more fault hunting to do once they are replaced.However the fact that both inverters apparently did exactly the same hopefully suggests it may be the cause, though of course the capacitors could have failed ages ago, only being noticed when I opened up the inverters.I am hoping that the Panasonic replacement caps whch are each rated for 3.68A ripple @ 105°C and have an impedance of 0.015 ohm will run cooler.

author: trobbins
author_rank: Frequent Contributor
timestamp: January 03, 2024, 03:04:50 am
content: It's amazing how posters at the start of this thread piled on with negative reactions from just a whiff of failure.Recent posts highlight how much the application, and equipment design, may well be at the root cause of some observed cap failures. Perhaps the commercial pressure, and/or naivity of pcb/design copycats is mostly the concern here, as people purchase the cheapest and highest density power equipment like inverters with also a naive hope that all inside is well laid out and with all parts kept close to ambient temp through adequate thermal cooling paths.

author: Spar59
author_rank: Contributor
timestamp: January 08, 2024, 10:38:38 pm
content: The previous post is very true - the sort by: "Lowest cost first" mentality is not going to get you the best quality or best designed equipment.In that context the quality of the internal components is obviously not going to be the best.I think I mentioned the inverters were cheap, they are part an experimental solar plus time of day usage transfer sytem (i.e. charge batteries on cheap rate electricity, use the energy at expensive times).They had other issues such as:1. Heatsink clamps packed with folded newspaper rather than just taking the time to align the clamps properly.2. Temperature sensing is inadequate and makes the unit orientation sensitive. Not an issue if "This way up" is printed on it or mentioned in the manual, I spotted it as my 2 inverters are mirror-image mounted and when carrying identical loads one ran a lot hotter than the other - you do not place the fan control temperature sensor in what will be the coolest part of the unit!!!! I added an extra sensor.3. The control circuits having no protection other than the main 75A (3x 25A in parallel) DC input fuse which could obviously cause significant damage including destruction of the PCB in the case of a fault, my attention was brought to this by the failure of a DC-DC converter - the smoke and flames were quite spectacular but the fuses did not blow and the 63A MCB on the DC distribution board did not trip, the converter was built as a daughter board whose PCB tracks became the fuse, daughter board burnt beyond repair, I replaced it with an off board converter and added a fuse, the second inverter got a fuse added proactively.4. PCB quality is pretty good, machine soldering good, hand soldering poor.On the other hand my second-hand APC upss have been in service with me for over a decade, no faults, although someone has reverse engineered one and found a sneak circuit that can overheat two resistors under certain conditions, but as they are decent components although overloaded they discolour rather than fail outright. I also have a Compaq one, similar vintage, again no faults.Regarding my failed inverters, changing all the input filter/reservoir capacitors, not just the obviously failed/distressed ones, has cured the faults, the replacement capacitors are from the Panasonic "FC" range and run significantly cooler than the originals so are obviously better suited to the large ripple current - the reason I selected them.