Comparing ripple current on capacitors with different temperature rating

[Y. Signal]

Hello. I'm looking for good quality general purpose caps rated at 105 C. After reading this forum I have concluded that these ones are good:

- Rubycon PX
- Chemi-con KMG

The problem is that the datasheets have ripple current data at 105 C while the ripple current data I have from the old capacitors is rated at 85 C. How can I know if the capacitor is appropiate without having ripple current ratings at the same temperature?

[stj]

Re: Comparing ripple current on capacitors with different temperature rating

temperature effects life, not ripple.

dont overlook rubycon YXF

[Y. Signal]

Re: Comparing ripple current on capacitors with different temperature rating

Although Rubycon YXF capacitors appear as GP in the Rubycon catalog they are in the low ESR category. I'm looking for standard GP caps.

Are you sure of that? in the Chemi-con SME datasheet there is a Ripple Current Multiplier for Ambient Temperature. I can't find that data in Rubycon datasheets.

If the temperature doesn't effect ripple, are Rubycon PK way superior to Rubycon PX? both Standard GP, 85 C and 105 C respectively. PK would have considerably higher ripple current.

[stj]

Re: Comparing ripple current on capacitors with different temperature rating

they are just bordering on low - i use them for GP applications.

i dont have pk or px datasheets in front of me,
but i have noticed in the past that 85' caps can have higher ripple than 105' - having said that, lower esr allows for higher ripple.
so your fighting a losing battle trying to get high ripple AND high esr.

[Y. Signal]

Re: Comparing ripple current on capacitors with different temperature rating

Maybe although ESR is not affected by ambient temperature it can affect the ripple current that the capacitor can manage?

I'm looking for 105 C general purpose not low-esr capacitors that are slightly better than these ones: Chemi-con SME, Nichicon VX and Rubycon CE W.

Ripple current for 100uF 16V:

Nichicon VX(M): 160
Chemi-con SME: 180

Possible alternatives:

Chemi-con KMG: 110
Rubycon PX: 130
Rubycon PK: 175

Rubycon PK seems adequate but it's only 85C. Rubycon YXF is way higher (~ 70%) with 250.

[Andrew F. Ali]

Re: Comparing ripple current on capacitors with different temperature rating

What application would you be using these caps that you are asking about? From what I am reading, either you are just guessing or just not sure what you are talking about. You have been given your answer but you still want more. Can't eat your cake and have it at the same time. Excuse me.

[brethin]

Re: Comparing ripple current on capacitors with different temperature rating

temperature effects life, not ripple.

Exactly!

[PeteS in CA]

Re: Comparing ripple current on capacitors with different temperature rating

Although Rubycon YXF capacitors appear as GP in the Rubycon catalog they are in the low ESR category. I'm looking for standard GP caps.
...

Assuming the GP part was used appropriately, "general purpose" means the application is not stressful. In other words, any part will work fine.

A part that is rated for 105C will tend to last longer than an 85C part in an environment that does not exceed 85C.

A lower impedance (or ESR) part will self-heat due to ripple current less than a general purpose part. But in a general purpose application the self-heating due to ripple current is not going to be very great.

All in all, you can use a good low impedance part like Nichicon PW or HE, or Nippon Chemicon LXZ or KY or KZE, or Rubycon ZL in a general purpose application and it will perform well. I would suggest the main factors you should look at are rated life, price, and availability. And consider, too, how long you want your device to last. A 5000 hour rated part (which will last much longer at temperatures below the maximum rating) may do as well as a 10000 hour part if the expected life of your electronic device isn't much greater than the expected life of the capacitor.

Personally, I've had good experience with all the series I listed above and would not hesitate to use any of them in a general purpose application, unless a general purpose part were significantly less expensive.

YXF is simply one of Rubycon's older (or oldest) low impedance series. Nichicon's PS series is too, sort of, and probably of similar performance. These series are probably especially useful in replacing the output capacitors of switching power supplies that are more than 20 years old. Their performance is similar to that of the original parts, and thus less likely to cause stability issues (which a much lower impedance part might do).

[Wester547]

Re: Comparing ripple current on capacitors with different temperature rating

temperature effects life, not ripple.

dont overlook rubycon YXF

Electrolytic capacitors do have ripple current multipliers which allow them to conduct more ripple current at lower temperatures. The rather elderly but still pertinent KMG datasheet I attached (on page 2) shows the multipliers for lower temperatures (1x at 105ºC and 1.75x at 85ºC). What determines the ripple current multiplier is the maximum permitted core temperature rise, which varies anywhere between 40ºC and the maximum category temperature (85ºC and 105ºC). At low temperatures, for 105ºC capacitors, the maximum permitted core temperature rise can be anywhere from 15ºC to 30ºC, depending on the series and brand. At very high temperatures such as those the capacitors are rated for, the limit is around 5ºC to 10ºC - sometimes even as low as 3ºC for some series (LXZ/LXY/LXV and a few others come to mind, according to NCC).

[Y. Signal]

Re: Comparing ripple current on capacitors with different temperature rating

Thank you all for the information, I'm trying to learn how to properly choose the best caps.

Some time ago I recapped two Sega Mega Drive consoles with Panasonic FR capacitors and after 1 hour of use they produced video noise. Later I recapped them with Panasonic FC and they worked fine, no problem even using them >4 hours in a row.

Since then I've used Rubycon YXF and apparently these capacitors work fine for this application, but I have noticed horizontal interference in a console (similar to this video but not so pronnounced) after 30 minutes to 1 hour of use. I'm not saying the YXF are the cause of this problem, but anyway I want to stay in the safe side using just slightly better caps.

Assuming the GP part was used appropriately, "general purpose" means the application is not stressful. In other words, any part will work fine.

Then in this case I suppose the Rubycon PX will be fine. Thanks.

[stj]

Re: Comparing ripple current on capacitors with different temperature rating

hmm
i'd be wanting to hook the console to my tek wvr500