PCBONEZ wrote:BRAVO!! - You remembered the Cap Map!
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Many PSUs use 85°C primaries so i wouldn't be -that- worried about it.
The 105° would -p […]
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BRAVO!! - You remembered the Cap Map!
.
Many PSUs use 85°C primaries so i wouldn't be -that- worried about it.
The 105° would -probably- last longer but that's assuming typical Endurance ratings and similar starting Life Spans.
Muliti piece explanation to follow.
People mistake Endurance (aka Load Life) as Life Spam - but that's not what it is.
A cap rated for 1000Hrs @85°C means it can handle max-voltage(+)max-ripple(+)85°C for 1000 hours without anything going out of spec.
In other words it how long you can abuse it and cause no lasting damage.
There are equations to get from Load Life (Endurance) to Life Span but they are given as +/-40% accurate and IMHO are a waste of time.
Lets say the actual Life Span is 15 years. The equations might tell you anything from 9 to 21 years, we'll say it said 20 years.
So the equations told you the Life Span is 20 years - and you can't know if that's the high, low, or middle of the +/-40% range.
Useless IMHO. - And this is why caps companies don't give numbers for Life Span in datasheets.
The equations are going to be a crystal ball guess because the actual application conditions over the component's lifespan will be highly variable and therefore difficult to anticipate.
PCBONEZ wrote:Capacitor companies do say that lowering the temp 10°C will double a capacitors Life Span.
That works for Endurance as well beca […]
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Capacitor companies do say that lowering the temp 10°C will double a capacitors Life Span.
That works for Endurance as well because the °C is in the same place both equations.
(If you change temp the changes to Endurance and Life Span are proportional to each other.)
Thus if you lower the temp 10°C you will double the Endurance also.
Interestingly, it's the same rule of thumb for magnetics.
PCBONEZ wrote:Now, back to your caps:
We will say the 105°C cap has an Endurance of 1000 Hrs
@105°C = 1000hr
@95°C = 2000hr
@85°C = 4000hr
I […]
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Now, back to your caps:
We will say the 105°C cap has an Endurance of 1000 Hrs
@105°C = 1000hr
@95°C = 2000hr
@85°C = 4000hr
If your 85°C cap is rated for more than 4000hrs it might last longer.
("might" because we don't actually know the Life Span of either one. We are assuming they are similar.)
I did all that to teach the concept.
In the real world crap brand primary caps are usually rated for 1000-2000 hours regardless of temp rating.
[And now finally the answer!] - The odds are the 105°C will last longer.
[EDIT]
The Fuhjyyu MK is 2000Hrs and 700 mA Ripple@120Hz
What series is the ChengX ??
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I apologize in advance, I really like to create hypothetical examples which are completely unrealistic. If that's leading too far away from the real world, please yank me back into line.
I like the information you've included in this posting. Just to expand on what you've said, I'll tie it back to what I mentioned earlier.
The two primary enemies of electrical components in application are over voltage and overheating. Obviously, the ambient temperature spec for a capacitor will affect how resilient it is to heating. Using Bonez' example, if you put the Fuhjyyu cap in a box heated to 85 degrees C and hit it with the specified ripple current, enough heat will transfer out of the casing for the cap to maintain an interior temperature such that it survives 2000 hrs. In application, the box won't be always at 85 degrees, and the ripple current won't be the same either, but you can extract a general idea of how tough the component is (as long as nobody lied about the specs).
A cap with the same endurance and ripple spec designed for 105 degree ambient will be of a geometry and construction that allows it to withstand higher interior temperature, be more effective at exhausting heat, or both. A cap with the same endurance and ambient temperature spec but less ripple current will experience less ohmic heating of the component interior under testing -- geometry and construction will be for less demanding conditions.
There is a maximum lifetime for capacitors as well. Eventually, exposure to Earths nasty atmosphere will destroy most plastics and rubbers, so these rules don't apply indefinitely.
For more information, see this nice document from Chemi Con.
http://www.mouser.com/pdfDocs/UCC_Electrolyti … hnicalNotes.pdf
. Sounds like it's the -12V cap, dark blue wire close-by?
