KEMET vs Aishi caps - Page 1
Forum section: electronics / projects

author: stoyanoff
author_rank: Contributor
timestamp: September 11, 2023, 04:37:02 pm
content: Greetings! I am trying to make a comparison between KEMET(made in eu) 450V 2200uF electrolyte caps and Aishi 450V 2200uF made in China. The price is double in favour of the Aishi, but does it worth it?I will use it in a frequency inverter up to 100A/550V on the bridge. 2 caps in parallel (2x450V). Can you share any experience?Thanks!

author: sparkydog
author_rank: Regular Contributor
timestamp: September 11, 2023, 04:51:09 pm
content: Computer power supplies (and maybe motherboards?) are always advertisingJapanesecaps. Any reason you aren't considering e.g. Nichicon?

author: wraper
author_rank: Unknown
timestamp: September 11, 2023, 05:14:11 pm
content: Why do you think Kemet will be made in EU? Kemet is an American company now owned by Taiwanese Yageo, so you could be buying Yageo caps under Kemet branding, the same as Teapo and Jamicon. Aishi capacitors are OK. And you should be comparing particular series, not just brands. They make different series with different specs.

author: stoyanoff
author_rank: Contributor
timestamp: September 11, 2023, 07:14:12 pm
content: Quote from: wraper on September 11, 2023, 05:14:11 pmThere are mainly Kemet caps in the shops. I think it depends on the seller. Because I saught a kemet factory in eu. I don`t have access to Japanese caps. They are in low quatities and available values in the main shops.

author: floobydust
author_rank: Super Contributor
timestamp: September 11, 2023, 07:18:37 pm
content: I find Aishi are low quality. They heat up quite a bit from ESR and then dry out fast. All they have is a thick heatshrink wrapper but otherwise I would not use them at all.

author: wraper
author_rank: Unknown
timestamp: September 11, 2023, 07:58:47 pm
content: Quote from: floobydust on September 11, 2023, 07:18:37 pmQuite a bold and overbroad claim. Did you measure if ESR/dissipation factor is within specified in the datasheet for particular series or not? Did you measure them heating more than other caps with similar specs? I don't say Aishi caps are of particularly high quality, however they can be most often found in lighting products such as LED bulbs or electronic ballasts which run scotching hot and thus capacitors are abused like hell. So seeing failed capacitors in those is not surprising at all.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2023, 09:14:20 pm
content: Quote from: stoyanoff on September 11, 2023, 07:14:12 pmMost passive makers have a number of plants, each of which specialises in a few products. They probably have a few product lines made in a JV plant, so its shared with very similar products from one or two other makers. They may also buy in some products from third parties, to have a fuller offering. So, finding a company has a plant in particular country tells you very little. There is a whole speciality, typically called something like component engineering, where someone specialises in keeping track of who makes what and where. That is really important for high volume manufacturers. Without it production lines are regularly down when some component becomes unavailable.Designer: "This one looks good. Three people make it, so it multiply sourced"Component specialist: "Er, no. I've done the factory inspection, and all of those products are coming off the same line.".Designer: "This chip looks solid. We have two people making their own compatible dies, in different fabs."Component specialist: "Er, I've done the inspection, and Kyocera makes the package both of them use".Achieving reliable component supply is such fun.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 11, 2023, 11:28:00 pm
content: The manufacturers who make decent capacitors often have a whole lot of different series. Different temperatures, extra compact, low ESR, different price points just to name a few variables. So comparing a "random" capacitor from one manufacturer with a "random" capacitor from another manufacturer does not make any sense.

author: CosteC
author_rank: Regular Contributor
timestamp: September 12, 2023, 09:43:38 am
content: Without knowing exact types and working conditions its hard to tell is KEMET worth the price.What is ripple current, required ESR, ambient temperature? Do you need miniaturised version or large is fine? Many questions.

author: floobydust
author_rank: Super Contributor
timestamp: September 18, 2023, 08:12:08 pm
content: Quote from: wraper on September 11, 2023, 07:58:47 pmI have a few new SMPS with Aishi capacitors that ran very hot during load testing. Promptly swapped them out for basic (not low ESR) Nichicon, Chemi-con parts which (surprise!) run cool. So there is a problem with dielectric heating. That was the last straw. The rubber bung is also cheap so I see them as mediocre quality despite the marketing hype and pride.I had researched ChongX, ChangX, ChengX to see the shell-game the chinese play. They will make a capacitor company on the SSE/HK exchange, maybe registered in the Cayman Islands, do the usual pump and dump with stock price and sell total garbage low quality parts, then they get de-listed when the party is over. Rinse and repeat. Check Aishi stock price...Big problem is OP's application has high energy on the DC bus so a failed capacitor will likely explode and start a fire. Are the "savings" then worth it?Also the engineering behind cooling the bus caps, not in an array where the inside parts run hottest due to poor airflow- but proper spacing and a blast shield is important.CDE wants their engineering team to review the cooling design, towards meeting lifetime specs.Even good quality capacitors get abused by cheapness - using undersized parts that experience too much ripple current and have a short life. This is the norm for consumer electronics.