Specs of electrolytic capacitors

[Faringdon]

Hi,
The  687KXM025M (680uF , 25v) electrolytic capacitor is far better than the UPS1E681MPD  (680uF , 25v) electrolytic capacitor.

It has a lifetime of 4000 hrs vs  2000 hrs, its ripple current rating (at 100khz) is 1.8A vs 1A.
Yet its price is £0.09 @ 8k   vs £0.15 @ 5k.
It costs 50% less!!!

By rights , nobody should be using the UPS1E681MPD. Why are they?
Are the specs not always to be trusted or something?

687KXM025M (680uF , 25v) Electrolytic capacitor
https://www.illinoiscapacitor.com/pdf/seriesDocuments/KXM%20series.pdf

UPS1E681MPD  (680uF , 25v) Electrolytic capacitor
https://www.nichicon.co.jp/english/products/pdfs/e-ups.pdf

[TimFox]

Are you comparing the prices at two different quantities (8k and 5k), or was that a typo?

[pardo-bsso]

Besides the difference in order quantity to have that price do mind that they have different purposes specified in their datasheets (one gp. the other for switching supplies).

Also the one from Nichicon has to make a long travel from Japan and somedays the earth rotation is in the wrong way.


pps: say Hi to Treez, I liked that handle a bit more than this one.

[T3sl4co1l]

ESR is different by ~4x.

IC is American (CoO who knows?), maybe not as available in certain markets.  Or just different availability.  IC wasn't stocked at DK until relatively recently (some years back) but they've been around a long time otherwise (I recall first seeing them at Allied).

Cost still doesn't really mean much.  Try quoting more like 100k of each, from various suppliers or in various locations on the planet, and see what it is then?

Tim

[Faringdon]

Hi, Please may i put forward this similar question?...
*******************************************************************************
We have a 3V3 rail that supplies only 20mA.
But we want some bulk capacitance on it. Elsewhere on the same board we  are already using several 100uF , 25V Al Electrolytic capacitors. Therefore , we  elect to simply use one of these on the 3V3 rail to provide bulk capacitance.
We  have two   100Uf, 25V Al Electrolytic capacitors to choose from….
1).. 25ZL100MEFCT16.3X11
Or..
2).. 25YXJ100MTA5X11
..We want to choose the one that will last the longest, say if the customer uses the equipment in a hot environment…we want to choose the capacitor that will take longer to dry out.
But which one will avoid drying out for the longer time?
25ZL100MEFCT16.3X11 is said to be rated for  0.4A ripple at 100khz and  rated for 2000 hrs at 105degC, whereas 25YXJ100MTA5X11 is rated for 0.25A ripple at 100khz, but rated for  7000 hrs at 105degC.

……do you agree that its impossible to know which capacitor will last longest?, since there quoted ripple currents are different…in other words, the  25YXJ100MTA5X11 is said to last for the longer time, but this is when running at only half the ripple current as the  25ZL100MEFCT16.3X11
*******************************************************************************

[The Soulman]

How much ripple current do you expect on your 3,3 Volt "20mA" rail??

[Faringdon]

How much ripple current do you expect on your 3,3 Volt "20mA" rail??

Virtually none........its fed by a linear reg from 5V....and its only get a few micros on it.

Also, what do you think about running a 25V electrolytic on a 3V3 rail.........i had heard that an Al El cap needs at least 10% of its rated voltage on it before it "forms" properly.......3v3 isnt far off 10% of 25v.......maybe the "100uf" Al El cap wont be anywhere near 100uF?


**************************************************
Please may i ask another related question  here?...as i know its bad to start multiple threads on the same theme......
The below article states that a 10degC reduction in  ambient temperature for a Aluminium polymer capacitor results in a ten-fold increase in lifetime. Is this true?....I have heard Arrhenius' Law....but never this "ten-fold" law.

https://www.rs-online.com/designspark/aluminum-electrolytic-vs-aluminum-polymer-capacitor-and-how-its-benefits-are-used-properly
**************************************************

[SeanB]

Use the longer life one, the ripple current rating will only add a small amount of extra heat if you run at full rated current, but the longer life one will last longer, if it runs around the same temperature, and with a current well under the max rated ripple. Derate for lower operation temperature and the 5000 hours extra will be well ahead of the other, as each 10C drop in operation temperature will offer more than double the rated life of the other, and thus if they run at a typical 75C the first will last 16000 hours, say 2 years, while the other will last 56000 hours, roughly 7 years, and this will increase for every lowering of operation temperature, say by not having a hot regulator cooking the capacitor, and having some airflow across the board.

As to voltage a modern capacitor is fine with lower voltage, your 25V capacitor will be fine with 3V3 applied, and will last just as long. modern branded capacitors with quality pure aluminium foils do not degrade as badly as no name unknown impurity foil types, or very old ones with very old foil, made before QC got to the point they could remove down to the PPM level in the manufacturing.

[Faringdon]

Try quoting more like 100k of each, from various suppliers or in various locations on the planet, and see what it is then?

Thanks, i compared them on findchips.com.
I believe that this is the best way in the world to compare the prices of two electronic components?.....

687KXM025M
https://www.findchips.com/search/687KXM025M

UPS1E681MPD
https://www.findchips.com/search/UPS1E681MPD

[Siwastaja]

Free market is funny. Price doesn't always reflect quality or suitability for a specific task. It's well possible a certain part is better for your application. It's even possible a cheaper part to be better in every regard!

Look at specs and the reputability of the manufacturer. If OK, cheap price isn't a problem, quite the opposite.

You are indeed right that it's hard to see which part is better if one has lower ripple current rating but longer lifetime rating at that ripple current rating.

Derating is the key to success. Derate voltage by 30-40%, derate ripple current by 50%, derate ambient temperature by 30-40 degC and you have a very long-life cap. I.e., a 25V 1.0A 105degC cap becomes a 16V, 0.5A, 70 degC part that lasts for many tens if not hundreds of thousands of hours.

[Faringdon]

Thanks, please also assist with  dispelling/confirming these myths about capacitors....
(its a slightly new question but better than starting multiple new threads)
**********************************************************************
Myth 1: Wet  Al Elec caps suffer damage due to  high keakage current due to storage for >2 years at <40degC.

..This is not true, the leakage current is too low to cause damage, and reduces after 30 mins or so of having voltage applied
Myth 2: Wet Al elec caps are  far more prone to damage  than other cap types if stored for > 2 years at >40degc

..this  is true
Myth 3: You can always be sure that any batch of Wet Al elec caps that you order has been stored for <2 years at <40degC

..This is not true. Any batch of wet Al elec caps may have been stored for >2 years at >40degc but distributors may try and disguise them as being fresh....since caps are  cheap and not cost effective when stored in expensive temperature controlled environments. Also, electronics co's dont test caps for "state of health"  before fitting them to PCBs.
A Wet Al elec cap thats been stored for >2 years at >40degc is likely to have a lifetime far shorter than datasheet states.
Myth 4: Tantalum caps are more prone to damage  (than any other sold dielectric cap) due to high surge currents.

This is not true, they just  tend to have higher surge currents when a voltage is suddenly applied since they tend to have higher capacitance in smaller case sizes.
Myth 5:  Al elec caps suffer less wearout if operated significantly below rated voltage

..this is not true, this is only true for film caps
Myth 6: Film caps can better withstand surge currents than wet  Al Elec caps.

..This is not true. We t Al Elec caps are the kings of surge current withstand
Myth 7: Wet Al Elec caps suffer dry out of their dielectric even when not loaded

..This is true, due to them being imperfectly  sealed.
Myth 8: Small thin wet Al elec  caps suffer worse dielectric  dryout than taller/thicker wet Al elec caps

..This is true
Myth 9: A 10uf,0805,x7r,16V capacitor is more prone to cracking damage due to physical abuse than a  4.7uf,0805,x7r,16V capacitor.

..This is true
Myth 10: If a Solid polymer Al elec cap is run at 10degC less, then its lifetime increases by 10 times.
..This is not true, its 2 times.
Myth 11: MLCC caps of size 1206 and greater are far more likely to suffer stress cracks than MLCC caps of size 0805 and less

..this is true
**********************************************************************************

[Gyro]

Well that's an impressive list of gross over-generalisations you have there, treez.

[Faringdon]

I think "Myth 3"  is the one thats shocking...and "Myth 7"
Also, "Myth 4" is definetly nonsense.

[mariush]

Thanks, i compared them on findchips.com.
I believe that this is the best way in the world to compare the prices of two electronic components?.....

687KXM025M
https://www.findchips.com/search/687KXM025M

UPS1E681MPD
https://www.findchips.com/search/UPS1E681MPD

Findchips is a good start, but it doesn't contain all distributors of electronic components.

For example I'm not sure TME.EU is listed there, they have the PS capacitor but not in stock .. $0.22 at 400pcs , $0.20 at 1600 pcs : https://www.tme.eu/en/details/ups1e681mpd/tht-low-imped-electrolytic-capacitors/nichicon/

[mariush]

Myth 10: If a Solid polymer Al elec cap is run at 10degC less, then its lifetime increases by 10 times.
..This is not true, its 2 times.

**********************************************************************************

For regular electrolytic capacitors, it's acceptable to estimate double the number of hours for every 10c decrease from the maximum temperature rating .. ex a 2000h at 105c will be 4k at 95, 8k at 85, 16k at 75c etc

For solid polymer capacitors (no electrolyte), formula is different.

From https://www.illinoiscapacitor.com/tech-center/life-calculators.aspx