Do capacitors have maximum allowed amps rating?

[LearningToRepair]

Hi!

I am interested to know what happens to capacitors when too much load is applied? Do they only pop on overvolt or also on over load?

In SMPS caps are in parallel in order to get rid of ripple. If I exceed capacitors supply ability will I only get tons of ripple or will they also explode at the some point? And is there way to calculate max allowed amps for capacitor if I know actual volts, allowed max volts and capacitance? And also is there some rule that for example if I got this power supply from china then calculated maximum load should be divided by 3 to be safe for example?

Also do you have experiences, how reliable are chinese power supplies? They advertise it as LED power supply but LED lighting is something that during winter period could easily be powered 10+ hours in a row and I am curious if anyone have experience with long time use of chinese power supplies?


Some time ago I managed to pop chinese step up converter (I think I connected it in reverse polarity but I dont remember exactly anymore). And that pop was so loud that it was anything but fun. And now I am scared of every single power supply I see lol :P

[stj]

Re: Do capacitors have maximum allowed amps rating?

if the ripple exeeds the cap rating you just wont get smooth power - you wont blow it up.
chinese psu's are very varied.
some are good, some are..... well lets say shit would be putting it lightly!!!
https://www.youtube.com/channel/UCQa...B_Kd54g/videos

[LearningToRepair]

Re: Do capacitors have maximum allowed amps rating?

Thanks for info. Can I tell good psus from bad somehow? Like if I open it will there be any visual indicators? I mean if it visually looks bad then it is very likely bad but can I assume that if it visually looks well done then it is good one?

Also one more question: How much do capacitors need cooling? I want to modify fan to have 0 RPM mode if it is not hot enough. If that modification goes wrong would capacitors be one of the first things to pop or one of the last things to pop?

PS I have occasionally watched this YT channel. Haven't seen stuff to blow up there but 240V AV between iPhone case and ground was fun.

[petehall347]

Re: Do capacitors have maximum allowed amps rating?

they have max temp on them for rated hours ..the cooler they are kept the longer they last

[stj]

Re: Do capacitors have maximum allowed amps rating?

there is no magic temperature, the higher it is - the lower the life.
it's not a good idea to have fans switching up and down - find a good fixed speed.

[LearningToRepair]

Re: Do capacitors have maximum allowed amps rating?

there is no magic temperature, the higher it is - the lower the life.
it's not a good idea to have fans switching up and down - find a good fixed speed.

Thought I would ask - if I want powersupply for livingroom LED lighting setup and I want more power than those typical fanless supplies would give and I cant place that supply in an other room, what would be good options? One is rebuild case from scratch and have large fans with low RPM. Any alternatives to that?

[PeteS in CA]

Re: Do capacitors have maximum allowed amps rating?

In good quality electrolytics the ripple current rating is what the manufacturer guarantees the parts can do in the specified conditions for at least the specified number of hours. IRL, good quality parts may last much longer.

At Curtis Instruments, 2005-2009, my job included torture-testing electrolytic capacitors to see how long they would last under really extreme conditions. My test consisted of running ripple current through tested parts that was 8X-10X the parts' ratings for 22 hours a day. During the remaining 2 hours I let the parts cool to room temperature and measured the parts' capacitance and impedance (to track accumulating damage), and then restarted the torture. The test bore some relationship to real life usage but was still extreme compared to real life.

The really good parts would go for hundreds of hours, up to around 2000 hours, before venting or the impedance going way high. Crap caps sometimes vented within 24 hours and almost always in less than 100 hours. (BTW, United Chemicon KZG series parts did very poorly)

So, yeah, there is an insanely high value of ripple current that will quickly cause an electrolytic capacitor to vent dramatically, but real life applications probably are not capable of sourcing that much ripple current. A misapplied or low quality part will "just" have a relatively short lifetime, and might or might not vent a little bit of electrolyte on the top of the can.

[@udiophile99]

Re: Do capacitors have maximum allowed amps rating?

Hi!

I am interested to know what happens to capacitors when too much load is applied? Do they only pop on overvolt or also on over load?

In SMPS caps are in parallel in order to get rid of ripple. If I exceed capacitors supply ability will I only get tons of ripple or will they also explode at the some point? And is there way to calculate max allowed amps for capacitor if I know actual volts, allowed max volts and capacitance? And also is there some rule that for example if I got this power supply from china then calculated maximum load should be divided by 3 to be safe for example?

Also do you have experiences, how reliable are chinese power supplies? They advertise it as LED power supply but LED lighting is something that during winter period could easily be powered 10+ hours in a row and I am curious if anyone have experience with long time use of chinese power supplies?


Some time ago I managed to pop chinese step up converter (I think I connected it in reverse polarity but I dont remember exactly anymore). And that pop was so loud that it was anything but fun. And now I am scared of every single power supply I see lol :P

If you apply too much load, let's say you will have to forget about the smooth power. However, nothing will be damaged.

[momaka]

Re: Do capacitors have maximum allowed amps rating?

Also do you have experiences, how reliable are chinese power supplies? They advertise it as LED power supply but LED lighting is something that during winter period could easily be powered 10+ hours in a row and I am curious if anyone have experience with long time use of chinese power supplies?

Need more specifics into which power supply (or supplies) you're considering.

A lot of things are made in China - good stuff, cheap/mediorce stuff, and total garbage too. With "no-name" brands, though, the chance of getting that is somewhere between mediocre and garbage is really high.

Some time ago I managed to pop chinese step up converter (I think I connected it in reverse polarity but I dont remember exactly anymore). And that pop was so loud that it was anything but fun. And now I am scared of every single power supply I see lol :P

Well, if you mistreat or connect electronics improperly, there's always a chance it will pop/smoke, no matter if it's a good brand or a bad one. Of course, the better built stuff might stand a little more abuse or for longer... but in the end, you also need to do your part to make sure you connect things correctly too.

[jayjr1105]

Re: Do capacitors have maximum allowed amps rating?

So ripple current handling, is that the amount of amperage in the ripple the capacitor can handle or the amperage in general? Was always confused by this spec

[PeteS in CA]

Re: Do capacitors have maximum allowed amps rating?

The rated ripple current is the AC current the capacitor can handle at rated voltage and temperature and still have a life at least as long as its life rating. 10X the rated ripple current could be passed through a capacitor, but either a lead will open up like a fuse or it will have a much shorter life.